parse_utilcmd.c

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/*-------------------------------------------------------------------------
 *
 * parse_utilcmd.c
 *    Perform parse analysis work for various utility commands
 *
 * Formerly we did this work during parse_analyze() in analyze.c.  However
 * that is fairly unsafe in the presence of querytree caching, since any
 * database state that we depend on in making the transformations might be
 * obsolete by the time the utility command is executed; and utility commands
 * have no infrastructure for holding locks or rechecking plan validity.
 * Hence these functions are now called at the start of execution of their
 * respective utility commands.
 *
 * NOTE: in general we must avoid scribbling on the passed-in raw parse
 * tree, since it might be in a plan cache.  The simplest solution is
 * a quick copyObject() call before manipulating the query tree.
 *
 *
 * Portions Copyright (c) 1996-2012, PostgreSQL Global Development Group
 * Portions Copyright (c) 1994, Regents of the University of California
 *
 *  src/backend/parser/parse_utilcmd.c
 *
 *-------------------------------------------------------------------------
 */

#include "postgres.h"

#include "access/reloptions.h"
#include "catalog/dependency.h"
#include "catalog/heap.h"
#include "catalog/index.h"
#include "catalog/namespace.h"
#include "catalog/pg_collation.h"
#include "catalog/pg_constraint.h"
#include "catalog/pg_opclass.h"
#include "catalog/pg_operator.h"
#include "catalog/pg_type.h"
#include "commands/comment.h"
#include "commands/defrem.h"
#include "commands/tablecmds.h"
#include "commands/tablespace.h"
#include "miscadmin.h"
#include "nodes/makefuncs.h"
#include "nodes/nodeFuncs.h"
#include "parser/analyze.h"
#include "parser/parse_clause.h"
#include "parser/parse_collate.h"
#include "parser/parse_expr.h"
#include "parser/parse_relation.h"
#include "parser/parse_target.h"
#include "parser/parse_type.h"
#include "parser/parse_utilcmd.h"
#include "parser/parser.h"
#include "rewrite/rewriteManip.h"
#include "utils/acl.h"
#include "utils/builtins.h"
#include "utils/lsyscache.h"
#include "utils/rel.h"
#include "utils/syscache.h"
#include "utils/typcache.h"


/* State shared by transformCreateStmt and its subroutines */
typedef struct
{
    ParseState *pstate;         /* overall parser state */
    const char *stmtType;       /* "CREATE [FOREIGN] TABLE" or "ALTER TABLE" */
    RangeVar   *relation;       /* relation to create */
    Relation    rel;            /* opened/locked rel, if ALTER */
    List       *inhRelations;   /* relations to inherit from */
    bool        isalter;        /* true if altering existing table */
    bool        hasoids;        /* does relation have an OID column? */
    List       *columns;        /* ColumnDef items */
    List       *ckconstraints;  /* CHECK constraints */
    List       *fkconstraints;  /* FOREIGN KEY constraints */
    List       *ixconstraints;  /* index-creating constraints */
    List       *inh_indexes;    /* cloned indexes from INCLUDING INDEXES */
    List       *blist;          /* "before list" of things to do before
                                 * creating the table */
    List       *alist;          /* "after list" of things to do after creating
                                 * the table */
    IndexStmt  *pkey;           /* PRIMARY KEY index, if any */
} CreateStmtContext;

/* State shared by transformCreateSchemaStmt and its subroutines */
typedef struct
{
    const char *stmtType;       /* "CREATE SCHEMA" or "ALTER SCHEMA" */
    char       *schemaname;     /* name of schema */
    char       *authid;         /* owner of schema */
    List       *sequences;      /* CREATE SEQUENCE items */
    List       *tables;         /* CREATE TABLE items */
    List       *views;          /* CREATE VIEW items */
    List       *indexes;        /* CREATE INDEX items */
    List       *triggers;       /* CREATE TRIGGER items */
    List       *grants;         /* GRANT items */
} CreateSchemaStmtContext;


static void transformColumnDefinition(CreateStmtContext *cxt,
                          ColumnDef *column);
static void transformTableConstraint(CreateStmtContext *cxt,
                         Constraint *constraint);
static void transformTableLikeClause(CreateStmtContext *cxt,
                         TableLikeClause *table_like_clause);
static void transformOfType(CreateStmtContext *cxt,
                TypeName *ofTypename);
static IndexStmt *generateClonedIndexStmt(CreateStmtContext *cxt,
                        Relation source_idx,
                        const AttrNumber *attmap, int attmap_length);
static List *get_collation(Oid collation, Oid actual_datatype);
static List *get_opclass(Oid opclass, Oid actual_datatype);
static void transformIndexConstraints(CreateStmtContext *cxt);
static IndexStmt *transformIndexConstraint(Constraint *constraint,
                         CreateStmtContext *cxt);
static void transformFKConstraints(CreateStmtContext *cxt,
                       bool skipValidation,
                       bool isAddConstraint);
static void transformConstraintAttrs(CreateStmtContext *cxt,
                         List *constraintList);
static void transformColumnType(CreateStmtContext *cxt, ColumnDef *column);
static void setSchemaName(char *context_schema, char **stmt_schema_name);


/*
 * transformCreateStmt -
 *    parse analysis for CREATE TABLE
 *
 * Returns a List of utility commands to be done in sequence.  One of these
 * will be the transformed CreateStmt, but there may be additional actions
 * to be done before and after the actual DefineRelation() call.
 *
 * SQL92 allows constraints to be scattered all over, so thumb through
 * the columns and collect all constraints into one place.
 * If there are any implied indices (e.g. UNIQUE or PRIMARY KEY)
 * then expand those into multiple IndexStmt blocks.
 *    - thomas 1997-12-02
 */
List *
transformCreateStmt(CreateStmt *stmt, const char *queryString)
{
    ParseState *pstate;
    CreateStmtContext cxt;
    List       *result;
    List       *save_alist;
    ListCell   *elements;
    Oid         namespaceid;
    Oid         existing_relid;

    /*
     * We must not scribble on the passed-in CreateStmt, so copy it.  (This is
     * overkill, but easy.)
     */
    stmt = (CreateStmt *) copyObject(stmt);

    /*
     * Look up the creation namespace.  This also checks permissions on the
     * target namespace, locks it against concurrent drops, checks for a
     * preexisting relation in that namespace with the same name, and updates
     * stmt->relation->relpersistence if the select namespace is temporary.
     */
    namespaceid =
        RangeVarGetAndCheckCreationNamespace(stmt->relation, NoLock,
                                             &existing_relid);

    /*
     * If the relation already exists and the user specified "IF NOT EXISTS",
     * bail out with a NOTICE.
     */
    if (stmt->if_not_exists && OidIsValid(existing_relid))
    {
        ereport(NOTICE,
                (errcode(ERRCODE_DUPLICATE_TABLE),
                 errmsg("relation \"%s\" already exists, skipping",
                        stmt->relation->relname)));
        return NIL;
    }

    /*
     * If the target relation name isn't schema-qualified, make it so.  This
     * prevents some corner cases in which added-on rewritten commands might
     * think they should apply to other relations that have the same name and
     * are earlier in the search path.  But a local temp table is effectively
     * specified to be in pg_temp, so no need for anything extra in that case.
     */
    if (stmt->relation->schemaname == NULL
        && stmt->relation->relpersistence != RELPERSISTENCE_TEMP)
        stmt->relation->schemaname = get_namespace_name(namespaceid);

    /* Set up pstate and CreateStmtContext */
    pstate = make_parsestate(NULL);
    pstate->p_sourcetext = queryString;

    cxt.pstate = pstate;
    if (IsA(stmt, CreateForeignTableStmt))
        cxt.stmtType = "CREATE FOREIGN TABLE";
    else
        cxt.stmtType = "CREATE TABLE";
    cxt.relation = stmt->relation;
    cxt.rel = NULL;
    cxt.inhRelations = stmt->inhRelations;
    cxt.isalter = false;
    cxt.columns = NIL;
    cxt.ckconstraints = NIL;
    cxt.fkconstraints = NIL;
    cxt.ixconstraints = NIL;
    cxt.inh_indexes = NIL;
    cxt.blist = NIL;
    cxt.alist = NIL;
    cxt.pkey = NULL;
    cxt.hasoids = interpretOidsOption(stmt->options);

    Assert(!stmt->ofTypename || !stmt->inhRelations);   /* grammar enforces */

    if (stmt->ofTypename)
        transformOfType(&cxt, stmt->ofTypename);

    /*
     * Run through each primary element in the table creation clause. Separate
     * column defs from constraints, and do preliminary analysis.
     */
    foreach(elements, stmt->tableElts)
    {
        Node       *element = lfirst(elements);

        switch (nodeTag(element))
        {
            case T_ColumnDef:
                transformColumnDefinition(&cxt, (ColumnDef *) element);
                break;

            case T_Constraint:
                transformTableConstraint(&cxt, (Constraint *) element);
                break;

            case T_TableLikeClause:
                transformTableLikeClause(&cxt, (TableLikeClause *) element);
                break;

            default:
                elog(ERROR, "unrecognized node type: %d",
                     (int) nodeTag(element));
                break;
        }
    }

    /*
     * transformIndexConstraints wants cxt.alist to contain only index
     * statements, so transfer anything we already have into save_alist.
     */
    save_alist = cxt.alist;
    cxt.alist = NIL;

    Assert(stmt->constraints == NIL);

    /*
     * Postprocess constraints that give rise to index definitions.
     */
    transformIndexConstraints(&cxt);

    /*
     * Postprocess foreign-key constraints.
     */
    transformFKConstraints(&cxt, true, false);

    /*
     * Output results.
     */
    stmt->tableElts = cxt.columns;
    stmt->constraints = cxt.ckconstraints;

    result = lappend(cxt.blist, stmt);
    result = list_concat(result, cxt.alist);
    result = list_concat(result, save_alist);

    return result;
}

/*
 * transformColumnDefinition -
 *      transform a single ColumnDef within CREATE TABLE
 *      Also used in ALTER TABLE ADD COLUMN
 */
static void
transformColumnDefinition(CreateStmtContext *cxt, ColumnDef *column)
{
    bool        is_serial;
    bool        saw_nullable;
    bool        saw_default;
    Constraint *constraint;
    ListCell   *clist;

    cxt->columns = lappend(cxt->columns, column);

    /* Check for SERIAL pseudo-types */
    is_serial = false;
    if (column->typeName
        && list_length(column->typeName->names) == 1
        && !column->typeName->pct_type)
    {
        char       *typname = strVal(linitial(column->typeName->names));

        if (strcmp(typname, "smallserial") == 0 ||
            strcmp(typname, "serial2") == 0)
        {
            is_serial = true;
            column->typeName->names = NIL;
            column->typeName->typeOid = INT2OID;
        }
        else if (strcmp(typname, "serial") == 0 ||
                 strcmp(typname, "serial4") == 0)
        {
            is_serial = true;
            column->typeName->names = NIL;
            column->typeName->typeOid = INT4OID;
        }
        else if (strcmp(typname, "bigserial") == 0 ||
                 strcmp(typname, "serial8") == 0)
        {
            is_serial = true;
            column->typeName->names = NIL;
            column->typeName->typeOid = INT8OID;
        }

        /*
         * We have to reject "serial[]" explicitly, because once we've set
         * typeid, LookupTypeName won't notice arrayBounds.  We don't need any
         * special coding for serial(typmod) though.
         */
        if (is_serial && column->typeName->arrayBounds != NIL)
            ereport(ERROR,
                    (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                     errmsg("array of serial is not implemented"),
                     parser_errposition(cxt->pstate,
                                        column->typeName->location)));
    }

    /* Do necessary work on the column type declaration */
    if (column->typeName)
        transformColumnType(cxt, column);

    /* Special actions for SERIAL pseudo-types */
    if (is_serial)
    {
        Oid         snamespaceid;
        char       *snamespace;
        char       *sname;
        char       *qstring;
        A_Const    *snamenode;
        TypeCast   *castnode;
        FuncCall   *funccallnode;
        CreateSeqStmt *seqstmt;
        AlterSeqStmt *altseqstmt;
        List       *attnamelist;

        /*
         * Determine namespace and name to use for the sequence.
         *
         * Although we use ChooseRelationName, it's not guaranteed that the
         * selected sequence name won't conflict; given sufficiently long
         * field names, two different serial columns in the same table could
         * be assigned the same sequence name, and we'd not notice since we
         * aren't creating the sequence quite yet.  In practice this seems
         * quite unlikely to be a problem, especially since few people would
         * need two serial columns in one table.
         */
        if (cxt->rel)
            snamespaceid = RelationGetNamespace(cxt->rel);
        else
        {
            snamespaceid = RangeVarGetCreationNamespace(cxt->relation);
            RangeVarAdjustRelationPersistence(cxt->relation, snamespaceid);
        }
        snamespace = get_namespace_name(snamespaceid);
        sname = ChooseRelationName(cxt->relation->relname,
                                   column->colname,
                                   "seq",
                                   snamespaceid);

        ereport(DEBUG1,
                (errmsg("%s will create implicit sequence \"%s\" for serial column \"%s.%s\"",
                        cxt->stmtType, sname,
                        cxt->relation->relname, column->colname)));

        /*
         * Build a CREATE SEQUENCE command to create the sequence object, and
         * add it to the list of things to be done before this CREATE/ALTER
         * TABLE.
         */
        seqstmt = makeNode(CreateSeqStmt);
        seqstmt->sequence = makeRangeVar(snamespace, sname, -1);
        seqstmt->options = NIL;

        /*
         * If this is ALTER ADD COLUMN, make sure the sequence will be owned
         * by the table's owner.  The current user might be someone else
         * (perhaps a superuser, or someone who's only a member of the owning
         * role), but the SEQUENCE OWNED BY mechanisms will bleat unless table
         * and sequence have exactly the same owning role.
         */
        if (cxt->rel)
            seqstmt->ownerId = cxt->rel->rd_rel->relowner;
        else
            seqstmt->ownerId = InvalidOid;

        cxt->blist = lappend(cxt->blist, seqstmt);

        /*
         * Build an ALTER SEQUENCE ... OWNED BY command to mark the sequence
         * as owned by this column, and add it to the list of things to be
         * done after this CREATE/ALTER TABLE.
         */
        altseqstmt = makeNode(AlterSeqStmt);
        altseqstmt->sequence = makeRangeVar(snamespace, sname, -1);
        attnamelist = list_make3(makeString(snamespace),
                                 makeString(cxt->relation->relname),
                                 makeString(column->colname));
        altseqstmt->options = list_make1(makeDefElem("owned_by",
                                                     (Node *) attnamelist));

        cxt->alist = lappend(cxt->alist, altseqstmt);

        /*
         * Create appropriate constraints for SERIAL.  We do this in full,
         * rather than shortcutting, so that we will detect any conflicting
         * constraints the user wrote (like a different DEFAULT).
         *
         * Create an expression tree representing the function call
         * nextval('sequencename').  We cannot reduce the raw tree to cooked
         * form until after the sequence is created, but there's no need to do
         * so.
         */
        qstring = quote_qualified_identifier(snamespace, sname);
        snamenode = makeNode(A_Const);
        snamenode->val.type = T_String;
        snamenode->val.val.str = qstring;
        snamenode->location = -1;
        castnode = makeNode(TypeCast);
        castnode->typeName = SystemTypeName("regclass");
        castnode->arg = (Node *) snamenode;
        castnode->location = -1;
        funccallnode = makeNode(FuncCall);
        funccallnode->funcname = SystemFuncName("nextval");
        funccallnode->args = list_make1(castnode);
        funccallnode->agg_order = NIL;
        funccallnode->agg_star = false;
        funccallnode->agg_distinct = false;
        funccallnode->func_variadic = false;
        funccallnode->over = NULL;
        funccallnode->location = -1;

        constraint = makeNode(Constraint);
        constraint->contype = CONSTR_DEFAULT;
        constraint->location = -1;
        constraint->raw_expr = (Node *) funccallnode;
        constraint->cooked_expr = NULL;
        column->constraints = lappend(column->constraints, constraint);

        constraint = makeNode(Constraint);
        constraint->contype = CONSTR_NOTNULL;
        constraint->location = -1;
        column->constraints = lappend(column->constraints, constraint);
    }

    /* Process column constraints, if any... */
    transformConstraintAttrs(cxt, column->constraints);

    saw_nullable = false;
    saw_default = false;

    foreach(clist, column->constraints)
    {
        constraint = lfirst(clist);
        Assert(IsA(constraint, Constraint));

        switch (constraint->contype)
        {
            case CONSTR_NULL:
                if (saw_nullable && column->is_not_null)
                    ereport(ERROR,
                            (errcode(ERRCODE_SYNTAX_ERROR),
                             errmsg("conflicting NULL/NOT NULL declarations for column \"%s\" of table \"%s\"",
                                    column->colname, cxt->relation->relname),
                             parser_errposition(cxt->pstate,
                                                constraint->location)));
                column->is_not_null = FALSE;
                saw_nullable = true;
                break;

            case CONSTR_NOTNULL:
                if (saw_nullable && !column->is_not_null)
                    ereport(ERROR,
                            (errcode(ERRCODE_SYNTAX_ERROR),
                             errmsg("conflicting NULL/NOT NULL declarations for column \"%s\" of table \"%s\"",
                                    column->colname, cxt->relation->relname),
                             parser_errposition(cxt->pstate,
                                                constraint->location)));
                column->is_not_null = TRUE;
                saw_nullable = true;
                break;

            case CONSTR_DEFAULT:
                if (saw_default)
                    ereport(ERROR,
                            (errcode(ERRCODE_SYNTAX_ERROR),
                             errmsg("multiple default values specified for column \"%s\" of table \"%s\"",
                                    column->colname, cxt->relation->relname),
                             parser_errposition(cxt->pstate,
                                                constraint->location)));
                column->raw_default = constraint->raw_expr;
                Assert(constraint->cooked_expr == NULL);
                saw_default = true;
                break;

            case CONSTR_CHECK:
                cxt->ckconstraints = lappend(cxt->ckconstraints, constraint);
                break;

            case CONSTR_PRIMARY:
            case CONSTR_UNIQUE:
                if (constraint->keys == NIL)
                    constraint->keys = list_make1(makeString(column->colname));
                cxt->ixconstraints = lappend(cxt->ixconstraints, constraint);
                break;

            case CONSTR_EXCLUSION:
                /* grammar does not allow EXCLUDE as a column constraint */
                elog(ERROR, "column exclusion constraints are not supported");
                break;

            case CONSTR_FOREIGN:

                /*
                 * Fill in the current attribute's name and throw it into the
                 * list of FK constraints to be processed later.
                 */
                constraint->fk_attrs = list_make1(makeString(column->colname));
                cxt->fkconstraints = lappend(cxt->fkconstraints, constraint);
                break;

            case CONSTR_ATTR_DEFERRABLE:
            case CONSTR_ATTR_NOT_DEFERRABLE:
            case CONSTR_ATTR_DEFERRED:
            case CONSTR_ATTR_IMMEDIATE:
                /* transformConstraintAttrs took care of these */
                break;

            default:
                elog(ERROR, "unrecognized constraint type: %d",
                     constraint->contype);
                break;
        }
    }

    /*
     * Generate ALTER FOREIGN TABLE ALTER COLUMN statement which adds
     * per-column foreign data wrapper options for this column.
     */
    if (column->fdwoptions != NIL)
    {
        AlterTableStmt *stmt;
        AlterTableCmd *cmd;

        cmd = makeNode(AlterTableCmd);
        cmd->subtype = AT_AlterColumnGenericOptions;
        cmd->name = column->colname;
        cmd->def = (Node *) column->fdwoptions;
        cmd->behavior = DROP_RESTRICT;
        cmd->missing_ok = false;

        stmt = makeNode(AlterTableStmt);
        stmt->relation = cxt->relation;
        stmt->cmds = NIL;
        stmt->relkind = OBJECT_FOREIGN_TABLE;
        stmt->cmds = lappend(stmt->cmds, cmd);

        cxt->alist = lappend(cxt->alist, stmt);
    }
}

/*
 * transformTableConstraint
 *      transform a Constraint node within CREATE TABLE or ALTER TABLE
 */
static void
transformTableConstraint(CreateStmtContext *cxt, Constraint *constraint)
{
    switch (constraint->contype)
    {
        case CONSTR_PRIMARY:
        case CONSTR_UNIQUE:
        case CONSTR_EXCLUSION:
            cxt->ixconstraints = lappend(cxt->ixconstraints, constraint);
            break;

        case CONSTR_CHECK:
            cxt->ckconstraints = lappend(cxt->ckconstraints, constraint);
            break;

        case CONSTR_FOREIGN:
            cxt->fkconstraints = lappend(cxt->fkconstraints, constraint);
            break;

        case CONSTR_NULL:
        case CONSTR_NOTNULL:
        case CONSTR_DEFAULT:
        case CONSTR_ATTR_DEFERRABLE:
        case CONSTR_ATTR_NOT_DEFERRABLE:
        case CONSTR_ATTR_DEFERRED:
        case CONSTR_ATTR_IMMEDIATE:
            elog(ERROR, "invalid context for constraint type %d",
                 constraint->contype);
            break;

        default:
            elog(ERROR, "unrecognized constraint type: %d",
                 constraint->contype);
            break;
    }
}

/*
 * transformTableLikeClause
 *
 * Change the LIKE <srctable> portion of a CREATE TABLE statement into
 * column definitions which recreate the user defined column portions of
 * <srctable>.
 */
static void
transformTableLikeClause(CreateStmtContext *cxt, TableLikeClause *table_like_clause)
{
    AttrNumber  parent_attno;
    Relation    relation;
    TupleDesc   tupleDesc;
    TupleConstr *constr;
    AttrNumber *attmap;
    AclResult   aclresult;
    char       *comment;
    ParseCallbackState pcbstate;

    setup_parser_errposition_callback(&pcbstate, cxt->pstate, table_like_clause->relation->location);

    relation = relation_openrv(table_like_clause->relation, AccessShareLock);

    if (relation->rd_rel->relkind != RELKIND_RELATION &&
        relation->rd_rel->relkind != RELKIND_VIEW &&
        relation->rd_rel->relkind != RELKIND_COMPOSITE_TYPE &&
        relation->rd_rel->relkind != RELKIND_FOREIGN_TABLE)
        ereport(ERROR,
                (errcode(ERRCODE_WRONG_OBJECT_TYPE),
                 errmsg("\"%s\" is not a table, view, composite type, or foreign table",
                        RelationGetRelationName(relation))));

    cancel_parser_errposition_callback(&pcbstate);

    /*
     * Check for privileges
     */
    if (relation->rd_rel->relkind == RELKIND_COMPOSITE_TYPE)
    {
        aclresult = pg_type_aclcheck(relation->rd_rel->reltype, GetUserId(),
                                     ACL_USAGE);
        if (aclresult != ACLCHECK_OK)
            aclcheck_error(aclresult, ACL_KIND_TYPE,
                           RelationGetRelationName(relation));
    }
    else
    {
        aclresult = pg_class_aclcheck(RelationGetRelid(relation), GetUserId(),
                                      ACL_SELECT);
        if (aclresult != ACLCHECK_OK)
            aclcheck_error(aclresult, ACL_KIND_CLASS,
                           RelationGetRelationName(relation));
    }

    tupleDesc = RelationGetDescr(relation);
    constr = tupleDesc->constr;

    /*
     * Initialize column number map for map_variable_attnos().  We need this
     * since dropped columns in the source table aren't copied, so the new
     * table can have different column numbers.
     */
    attmap = (AttrNumber *) palloc0(sizeof(AttrNumber) * tupleDesc->natts);

    /*
     * Insert the copied attributes into the cxt for the new table definition.
     */
    for (parent_attno = 1; parent_attno <= tupleDesc->natts;
         parent_attno++)
    {
        Form_pg_attribute attribute = tupleDesc->attrs[parent_attno - 1];
        char       *attributeName = NameStr(attribute->attname);
        ColumnDef  *def;

        /*
         * Ignore dropped columns in the parent.  attmap entry is left zero.
         */
        if (attribute->attisdropped)
            continue;

        /*
         * Create a new column, which is marked as NOT inherited.
         *
         * For constraints, ONLY the NOT NULL constraint is inherited by the
         * new column definition per SQL99.
         */
        def = makeNode(ColumnDef);
        def->colname = pstrdup(attributeName);
        def->typeName = makeTypeNameFromOid(attribute->atttypid,
                                            attribute->atttypmod);
        def->inhcount = 0;
        def->is_local = true;
        def->is_not_null = attribute->attnotnull;
        def->is_from_type = false;
        def->storage = 0;
        def->raw_default = NULL;
        def->cooked_default = NULL;
        def->collClause = NULL;
        def->collOid = attribute->attcollation;
        def->constraints = NIL;

        /*
         * Add to column list
         */
        cxt->columns = lappend(cxt->columns, def);

        attmap[parent_attno - 1] = list_length(cxt->columns);

        /*
         * Copy default, if present and the default has been requested
         */
        if (attribute->atthasdef &&
            (table_like_clause->options & CREATE_TABLE_LIKE_DEFAULTS))
        {
            Node       *this_default = NULL;
            AttrDefault *attrdef;
            int         i;

            /* Find default in constraint structure */
            Assert(constr != NULL);
            attrdef = constr->defval;
            for (i = 0; i < constr->num_defval; i++)
            {
                if (attrdef[i].adnum == parent_attno)
                {
                    this_default = stringToNode(attrdef[i].adbin);
                    break;
                }
            }
            Assert(this_default != NULL);

            /*
             * If default expr could contain any vars, we'd need to fix 'em,
             * but it can't; so default is ready to apply to child.
             */

            def->cooked_default = this_default;
        }

        /* Likewise, copy storage if requested */
        if (table_like_clause->options & CREATE_TABLE_LIKE_STORAGE)
            def->storage = attribute->attstorage;
        else
            def->storage = 0;

        /* Likewise, copy comment if requested */
        if ((table_like_clause->options & CREATE_TABLE_LIKE_COMMENTS) &&
            (comment = GetComment(attribute->attrelid,
                                  RelationRelationId,
                                  attribute->attnum)) != NULL)
        {
            CommentStmt *stmt = makeNode(CommentStmt);

            stmt->objtype = OBJECT_COLUMN;
            stmt->objname = list_make3(makeString(cxt->relation->schemaname),
                                       makeString(cxt->relation->relname),
                                       makeString(def->colname));
            stmt->objargs = NIL;
            stmt->comment = comment;

            cxt->alist = lappend(cxt->alist, stmt);
        }
    }

    /*
     * Copy CHECK constraints if requested, being careful to adjust attribute
     * numbers so they match the child.
     */
    if ((table_like_clause->options & CREATE_TABLE_LIKE_CONSTRAINTS) &&
        tupleDesc->constr)
    {
        int         ccnum;

        for (ccnum = 0; ccnum < tupleDesc->constr->num_check; ccnum++)
        {
            char       *ccname = tupleDesc->constr->check[ccnum].ccname;
            char       *ccbin = tupleDesc->constr->check[ccnum].ccbin;
            Constraint *n = makeNode(Constraint);
            Node       *ccbin_node;
            bool        found_whole_row;

            ccbin_node = map_variable_attnos(stringToNode(ccbin),
                                             1, 0,
                                             attmap, tupleDesc->natts,
                                             &found_whole_row);

            /*
             * We reject whole-row variables because the whole point of LIKE
             * is that the new table's rowtype might later diverge from the
             * parent's.  So, while translation might be possible right now,
             * it wouldn't be possible to guarantee it would work in future.
             */
            if (found_whole_row)
                ereport(ERROR,
                        (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                         errmsg("cannot convert whole-row table reference"),
                         errdetail("Constraint \"%s\" contains a whole-row reference to table \"%s\".",
                                   ccname,
                                   RelationGetRelationName(relation))));

            n->contype = CONSTR_CHECK;
            n->location = -1;
            n->conname = pstrdup(ccname);
            n->raw_expr = NULL;
            n->cooked_expr = nodeToString(ccbin_node);
            cxt->ckconstraints = lappend(cxt->ckconstraints, n);

            /* Copy comment on constraint */
            if ((table_like_clause->options & CREATE_TABLE_LIKE_COMMENTS) &&
                (comment = GetComment(get_relation_constraint_oid(RelationGetRelid(relation),
                                                          n->conname, false),
                                      ConstraintRelationId,
                                      0)) != NULL)
            {
                CommentStmt *stmt = makeNode(CommentStmt);

                stmt->objtype = OBJECT_CONSTRAINT;
                stmt->objname = list_make3(makeString(cxt->relation->schemaname),
                                           makeString(cxt->relation->relname),
                                           makeString(n->conname));
                stmt->objargs = NIL;
                stmt->comment = comment;

                cxt->alist = lappend(cxt->alist, stmt);
            }
        }
    }

    /*
     * Likewise, copy indexes if requested
     */
    if ((table_like_clause->options & CREATE_TABLE_LIKE_INDEXES) &&
        relation->rd_rel->relhasindex)
    {
        List       *parent_indexes;
        ListCell   *l;

        parent_indexes = RelationGetIndexList(relation);

        foreach(l, parent_indexes)
        {
            Oid         parent_index_oid = lfirst_oid(l);
            Relation    parent_index;
            IndexStmt  *index_stmt;

            parent_index = index_open(parent_index_oid, AccessShareLock);

            /* Build CREATE INDEX statement to recreate the parent_index */
            index_stmt = generateClonedIndexStmt(cxt, parent_index,
                                                 attmap, tupleDesc->natts);

            /* Copy comment on index, if requested */
            if (table_like_clause->options & CREATE_TABLE_LIKE_COMMENTS)
            {
                comment = GetComment(parent_index_oid, RelationRelationId, 0);

                /*
                 * We make use of IndexStmt's idxcomment option, so as not to
                 * need to know now what name the index will have.
                 */
                index_stmt->idxcomment = comment;
            }

            /* Save it in the inh_indexes list for the time being */
            cxt->inh_indexes = lappend(cxt->inh_indexes, index_stmt);

            index_close(parent_index, AccessShareLock);
        }
    }

    /*
     * Close the parent rel, but keep our AccessShareLock on it until xact
     * commit.  That will prevent someone else from deleting or ALTERing the
     * parent before the child is committed.
     */
    heap_close(relation, NoLock);
}

static void
transformOfType(CreateStmtContext *cxt, TypeName *ofTypename)
{
    HeapTuple   tuple;
    TupleDesc   tupdesc;
    int         i;
    Oid         ofTypeId;

    AssertArg(ofTypename);

    tuple = typenameType(NULL, ofTypename, NULL);
    check_of_type(tuple);
    ofTypeId = HeapTupleGetOid(tuple);
    ofTypename->typeOid = ofTypeId;     /* cached for later */

    tupdesc = lookup_rowtype_tupdesc(ofTypeId, -1);
    for (i = 0; i < tupdesc->natts; i++)
    {
        Form_pg_attribute attr = tupdesc->attrs[i];
        ColumnDef  *n;

        if (attr->attisdropped)
            continue;

        n = makeNode(ColumnDef);
        n->colname = pstrdup(NameStr(attr->attname));
        n->typeName = makeTypeNameFromOid(attr->atttypid, attr->atttypmod);
        n->inhcount = 0;
        n->is_local = true;
        n->is_not_null = false;
        n->is_from_type = true;
        n->storage = 0;
        n->raw_default = NULL;
        n->cooked_default = NULL;
        n->collClause = NULL;
        n->collOid = attr->attcollation;
        n->constraints = NIL;
        cxt->columns = lappend(cxt->columns, n);
    }
    DecrTupleDescRefCount(tupdesc);

    ReleaseSysCache(tuple);
}

/*
 * Generate an IndexStmt node using information from an already existing index
 * "source_idx".  Attribute numbers should be adjusted according to attmap.
 */
static IndexStmt *
generateClonedIndexStmt(CreateStmtContext *cxt, Relation source_idx,
                        const AttrNumber *attmap, int attmap_length)
{
    Oid         source_relid = RelationGetRelid(source_idx);
    Form_pg_attribute *attrs = RelationGetDescr(source_idx)->attrs;
    HeapTuple   ht_idxrel;
    HeapTuple   ht_idx;
    Form_pg_class idxrelrec;
    Form_pg_index idxrec;
    Form_pg_am  amrec;
    oidvector  *indcollation;
    oidvector  *indclass;
    IndexStmt  *index;
    List       *indexprs;
    ListCell   *indexpr_item;
    Oid         indrelid;
    int         keyno;
    Oid         keycoltype;
    Datum       datum;
    bool        isnull;

    /*
     * Fetch pg_class tuple of source index.  We can't use the copy in the
     * relcache entry because it doesn't include optional fields.
     */
    ht_idxrel = SearchSysCache1(RELOID, ObjectIdGetDatum(source_relid));
    if (!HeapTupleIsValid(ht_idxrel))
        elog(ERROR, "cache lookup failed for relation %u", source_relid);
    idxrelrec = (Form_pg_class) GETSTRUCT(ht_idxrel);

    /* Fetch pg_index tuple for source index from relcache entry */
    ht_idx = source_idx->rd_indextuple;
    idxrec = (Form_pg_index) GETSTRUCT(ht_idx);
    indrelid = idxrec->indrelid;

    /* Fetch pg_am tuple for source index from relcache entry */
    amrec = source_idx->rd_am;

    /* Extract indcollation from the pg_index tuple */
    datum = SysCacheGetAttr(INDEXRELID, ht_idx,
                            Anum_pg_index_indcollation, &isnull);
    Assert(!isnull);
    indcollation = (oidvector *) DatumGetPointer(datum);

    /* Extract indclass from the pg_index tuple */
    datum = SysCacheGetAttr(INDEXRELID, ht_idx,
                            Anum_pg_index_indclass, &isnull);
    Assert(!isnull);
    indclass = (oidvector *) DatumGetPointer(datum);

    /* Begin building the IndexStmt */
    index = makeNode(IndexStmt);
    index->relation = cxt->relation;
    index->accessMethod = pstrdup(NameStr(amrec->amname));
    if (OidIsValid(idxrelrec->reltablespace))
        index->tableSpace = get_tablespace_name(idxrelrec->reltablespace);
    else
        index->tableSpace = NULL;
    index->excludeOpNames = NIL;
    index->idxcomment = NULL;
    index->indexOid = InvalidOid;
    index->oldNode = InvalidOid;
    index->unique = idxrec->indisunique;
    index->primary = idxrec->indisprimary;
    index->concurrent = false;

    /*
     * We don't try to preserve the name of the source index; instead, just
     * let DefineIndex() choose a reasonable name.
     */
    index->idxname = NULL;

    /*
     * If the index is marked PRIMARY or has an exclusion condition, it's
     * certainly from a constraint; else, if it's not marked UNIQUE, it
     * certainly isn't.  If it is or might be from a constraint, we have to
     * fetch the pg_constraint record.
     */
    if (index->primary || index->unique || idxrec->indisexclusion)
    {
        Oid         constraintId = get_index_constraint(source_relid);

        if (OidIsValid(constraintId))
        {
            HeapTuple   ht_constr;
            Form_pg_constraint conrec;

            ht_constr = SearchSysCache1(CONSTROID,
                                        ObjectIdGetDatum(constraintId));
            if (!HeapTupleIsValid(ht_constr))
                elog(ERROR, "cache lookup failed for constraint %u",
                     constraintId);
            conrec = (Form_pg_constraint) GETSTRUCT(ht_constr);

            index->isconstraint = true;
            index->deferrable = conrec->condeferrable;
            index->initdeferred = conrec->condeferred;

            /* If it's an exclusion constraint, we need the operator names */
            if (idxrec->indisexclusion)
            {
                Datum      *elems;
                int         nElems;
                int         i;

                Assert(conrec->contype == CONSTRAINT_EXCLUSION);
                /* Extract operator OIDs from the pg_constraint tuple */
                datum = SysCacheGetAttr(CONSTROID, ht_constr,
                                        Anum_pg_constraint_conexclop,
                                        &isnull);
                if (isnull)
                    elog(ERROR, "null conexclop for constraint %u",
                         constraintId);

                deconstruct_array(DatumGetArrayTypeP(datum),
                                  OIDOID, sizeof(Oid), true, 'i',
                                  &elems, NULL, &nElems);

                for (i = 0; i < nElems; i++)
                {
                    Oid         operid = DatumGetObjectId(elems[i]);
                    HeapTuple   opertup;
                    Form_pg_operator operform;
                    char       *oprname;
                    char       *nspname;
                    List       *namelist;

                    opertup = SearchSysCache1(OPEROID,
                                              ObjectIdGetDatum(operid));
                    if (!HeapTupleIsValid(opertup))
                        elog(ERROR, "cache lookup failed for operator %u",
                             operid);
                    operform = (Form_pg_operator) GETSTRUCT(opertup);
                    oprname = pstrdup(NameStr(operform->oprname));
                    /* For simplicity we always schema-qualify the op name */
                    nspname = get_namespace_name(operform->oprnamespace);
                    namelist = list_make2(makeString(nspname),
                                          makeString(oprname));
                    index->excludeOpNames = lappend(index->excludeOpNames,
                                                    namelist);
                    ReleaseSysCache(opertup);
                }
            }

            ReleaseSysCache(ht_constr);
        }
        else
            index->isconstraint = false;
    }
    else
        index->isconstraint = false;

    /* Get the index expressions, if any */
    datum = SysCacheGetAttr(INDEXRELID, ht_idx,
                            Anum_pg_index_indexprs, &isnull);
    if (!isnull)
    {
        char       *exprsString;

        exprsString = TextDatumGetCString(datum);
        indexprs = (List *) stringToNode(exprsString);
    }
    else
        indexprs = NIL;

    /* Build the list of IndexElem */
    index->indexParams = NIL;

    indexpr_item = list_head(indexprs);
    for (keyno = 0; keyno < idxrec->indnatts; keyno++)
    {
        IndexElem  *iparam;
        AttrNumber  attnum = idxrec->indkey.values[keyno];
        int16       opt = source_idx->rd_indoption[keyno];

        iparam = makeNode(IndexElem);

        if (AttributeNumberIsValid(attnum))
        {
            /* Simple index column */
            char       *attname;

            attname = get_relid_attribute_name(indrelid, attnum);
            keycoltype = get_atttype(indrelid, attnum);

            iparam->name = attname;
            iparam->expr = NULL;
        }
        else
        {
            /* Expressional index */
            Node       *indexkey;
            bool        found_whole_row;

            if (indexpr_item == NULL)
                elog(ERROR, "too few entries in indexprs list");
            indexkey = (Node *) lfirst(indexpr_item);
            indexpr_item = lnext(indexpr_item);

            /* Adjust Vars to match new table's column numbering */
            indexkey = map_variable_attnos(indexkey,
                                           1, 0,
                                           attmap, attmap_length,
                                           &found_whole_row);

            /* As in transformTableLikeClause, reject whole-row variables */
            if (found_whole_row)
                ereport(ERROR,
                        (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                         errmsg("cannot convert whole-row table reference"),
                         errdetail("Index \"%s\" contains a whole-row table reference.",
                                   RelationGetRelationName(source_idx))));

            iparam->name = NULL;
            iparam->expr = indexkey;

            keycoltype = exprType(indexkey);
        }

        /* Copy the original index column name */
        iparam->indexcolname = pstrdup(NameStr(attrs[keyno]->attname));

        /* Add the collation name, if non-default */
        iparam->collation = get_collation(indcollation->values[keyno], keycoltype);

        /* Add the operator class name, if non-default */
        iparam->opclass = get_opclass(indclass->values[keyno], keycoltype);

        iparam->ordering = SORTBY_DEFAULT;
        iparam->nulls_ordering = SORTBY_NULLS_DEFAULT;

        /* Adjust options if necessary */
        if (amrec->amcanorder)
        {
            /*
             * If it supports sort ordering, copy DESC and NULLS opts. Don't
             * set non-default settings unnecessarily, though, so as to
             * improve the chance of recognizing equivalence to constraint
             * indexes.
             */
            if (opt & INDOPTION_DESC)
            {
                iparam->ordering = SORTBY_DESC;
                if ((opt & INDOPTION_NULLS_FIRST) == 0)
                    iparam->nulls_ordering = SORTBY_NULLS_LAST;
            }
            else
            {
                if (opt & INDOPTION_NULLS_FIRST)
                    iparam->nulls_ordering = SORTBY_NULLS_FIRST;
            }
        }

        index->indexParams = lappend(index->indexParams, iparam);
    }

    /* Copy reloptions if any */
    datum = SysCacheGetAttr(RELOID, ht_idxrel,
                            Anum_pg_class_reloptions, &isnull);
    if (!isnull)
        index->options = untransformRelOptions(datum);

    /* If it's a partial index, decompile and append the predicate */
    datum = SysCacheGetAttr(INDEXRELID, ht_idx,
                            Anum_pg_index_indpred, &isnull);
    if (!isnull)
    {
        char       *pred_str;
        Node       *pred_tree;
        bool        found_whole_row;

        /* Convert text string to node tree */
        pred_str = TextDatumGetCString(datum);
        pred_tree = (Node *) stringToNode(pred_str);

        /* Adjust Vars to match new table's column numbering */
        pred_tree = map_variable_attnos(pred_tree,
                                        1, 0,
                                        attmap, attmap_length,
                                        &found_whole_row);

        /* As in transformTableLikeClause, reject whole-row variables */
        if (found_whole_row)
            ereport(ERROR,
                    (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                     errmsg("cannot convert whole-row table reference"),
                     errdetail("Index \"%s\" contains a whole-row table reference.",
                               RelationGetRelationName(source_idx))));

        index->whereClause = pred_tree;
    }

    /* Clean up */
    ReleaseSysCache(ht_idxrel);

    return index;
}

/*
 * get_collation        - fetch qualified name of a collation
 *
 * If collation is InvalidOid or is the default for the given actual_datatype,
 * then the return value is NIL.
 */
static List *
get_collation(Oid collation, Oid actual_datatype)
{
    List       *result;
    HeapTuple   ht_coll;
    Form_pg_collation coll_rec;
    char       *nsp_name;
    char       *coll_name;

    if (!OidIsValid(collation))
        return NIL;             /* easy case */
    if (collation == get_typcollation(actual_datatype))
        return NIL;             /* just let it default */

    ht_coll = SearchSysCache1(COLLOID, ObjectIdGetDatum(collation));
    if (!HeapTupleIsValid(ht_coll))
        elog(ERROR, "cache lookup failed for collation %u", collation);
    coll_rec = (Form_pg_collation) GETSTRUCT(ht_coll);

    /* For simplicity, we always schema-qualify the name */
    nsp_name = get_namespace_name(coll_rec->collnamespace);
    coll_name = pstrdup(NameStr(coll_rec->collname));
    result = list_make2(makeString(nsp_name), makeString(coll_name));

    ReleaseSysCache(ht_coll);
    return result;
}

/*
 * get_opclass          - fetch qualified name of an index operator class
 *
 * If the opclass is the default for the given actual_datatype, then
 * the return value is NIL.
 */
static List *
get_opclass(Oid opclass, Oid actual_datatype)
{
    List       *result = NIL;
    HeapTuple   ht_opc;
    Form_pg_opclass opc_rec;

    ht_opc = SearchSysCache1(CLAOID, ObjectIdGetDatum(opclass));
    if (!HeapTupleIsValid(ht_opc))
        elog(ERROR, "cache lookup failed for opclass %u", opclass);
    opc_rec = (Form_pg_opclass) GETSTRUCT(ht_opc);

    if (GetDefaultOpClass(actual_datatype, opc_rec->opcmethod) != opclass)
    {
        /* For simplicity, we always schema-qualify the name */
        char       *nsp_name = get_namespace_name(opc_rec->opcnamespace);
        char       *opc_name = pstrdup(NameStr(opc_rec->opcname));

        result = list_make2(makeString(nsp_name), makeString(opc_name));
    }

    ReleaseSysCache(ht_opc);
    return result;
}


/*
 * transformIndexConstraints
 *      Handle UNIQUE, PRIMARY KEY, EXCLUDE constraints, which create indexes.
 *      We also merge in any index definitions arising from
 *      LIKE ... INCLUDING INDEXES.
 */
static void
transformIndexConstraints(CreateStmtContext *cxt)
{
    IndexStmt  *index;
    List       *indexlist = NIL;
    ListCell   *lc;

    /*
     * Run through the constraints that need to generate an index. For PRIMARY
     * KEY, mark each column as NOT NULL and create an index. For UNIQUE or
     * EXCLUDE, create an index as for PRIMARY KEY, but do not insist on NOT
     * NULL.
     */
    foreach(lc, cxt->ixconstraints)
    {
        Constraint *constraint = (Constraint *) lfirst(lc);

        Assert(IsA(constraint, Constraint));
        Assert(constraint->contype == CONSTR_PRIMARY ||
               constraint->contype == CONSTR_UNIQUE ||
               constraint->contype == CONSTR_EXCLUSION);

        index = transformIndexConstraint(constraint, cxt);

        indexlist = lappend(indexlist, index);
    }

    /* Add in any indexes defined by LIKE ... INCLUDING INDEXES */
    foreach(lc, cxt->inh_indexes)
    {
        index = (IndexStmt *) lfirst(lc);

        if (index->primary)
        {
            if (cxt->pkey != NULL)
                ereport(ERROR,
                        (errcode(ERRCODE_INVALID_TABLE_DEFINITION),
                         errmsg("multiple primary keys for table \"%s\" are not allowed",
                                cxt->relation->relname)));
            cxt->pkey = index;
        }

        indexlist = lappend(indexlist, index);
    }

    /*
     * Scan the index list and remove any redundant index specifications. This
     * can happen if, for instance, the user writes UNIQUE PRIMARY KEY. A
     * strict reading of SQL92 would suggest raising an error instead, but
     * that strikes me as too anal-retentive. - tgl 2001-02-14
     *
     * XXX in ALTER TABLE case, it'd be nice to look for duplicate
     * pre-existing indexes, too.
     */
    Assert(cxt->alist == NIL);
    if (cxt->pkey != NULL)
    {
        /* Make sure we keep the PKEY index in preference to others... */
        cxt->alist = list_make1(cxt->pkey);
    }

    foreach(lc, indexlist)
    {
        bool        keep = true;
        ListCell   *k;

        index = lfirst(lc);

        /* if it's pkey, it's already in cxt->alist */
        if (index == cxt->pkey)
            continue;

        foreach(k, cxt->alist)
        {
            IndexStmt  *priorindex = lfirst(k);

            if (equal(index->indexParams, priorindex->indexParams) &&
                equal(index->whereClause, priorindex->whereClause) &&
                equal(index->excludeOpNames, priorindex->excludeOpNames) &&
                strcmp(index->accessMethod, priorindex->accessMethod) == 0 &&
                index->deferrable == priorindex->deferrable &&
                index->initdeferred == priorindex->initdeferred)
            {
                priorindex->unique |= index->unique;

                /*
                 * If the prior index is as yet unnamed, and this one is
                 * named, then transfer the name to the prior index. This
                 * ensures that if we have named and unnamed constraints,
                 * we'll use (at least one of) the names for the index.
                 */
                if (priorindex->idxname == NULL)
                    priorindex->idxname = index->idxname;
                keep = false;
                break;
            }
        }

        if (keep)
            cxt->alist = lappend(cxt->alist, index);
    }
}

/*
 * transformIndexConstraint
 *      Transform one UNIQUE, PRIMARY KEY, or EXCLUDE constraint for
 *      transformIndexConstraints.
 */
static IndexStmt *
transformIndexConstraint(Constraint *constraint, CreateStmtContext *cxt)
{
    IndexStmt  *index;
    ListCell   *lc;

    index = makeNode(IndexStmt);

    index->unique = (constraint->contype != CONSTR_EXCLUSION);
    index->primary = (constraint->contype == CONSTR_PRIMARY);
    if (index->primary)
    {
        if (cxt->pkey != NULL)
            ereport(ERROR,
                    (errcode(ERRCODE_INVALID_TABLE_DEFINITION),
             errmsg("multiple primary keys for table \"%s\" are not allowed",
                    cxt->relation->relname),
                     parser_errposition(cxt->pstate, constraint->location)));
        cxt->pkey = index;

        /*
         * In ALTER TABLE case, a primary index might already exist, but
         * DefineIndex will check for it.
         */
    }
    index->isconstraint = true;
    index->deferrable = constraint->deferrable;
    index->initdeferred = constraint->initdeferred;

    if (constraint->conname != NULL)
        index->idxname = pstrdup(constraint->conname);
    else
        index->idxname = NULL;  /* DefineIndex will choose name */

    index->relation = cxt->relation;
    index->accessMethod = constraint->access_method ? constraint->access_method : DEFAULT_INDEX_TYPE;
    index->options = constraint->options;
    index->tableSpace = constraint->indexspace;
    index->whereClause = constraint->where_clause;
    index->indexParams = NIL;
    index->excludeOpNames = NIL;
    index->idxcomment = NULL;
    index->indexOid = InvalidOid;
    index->oldNode = InvalidOid;
    index->concurrent = false;

    /*
     * If it's ALTER TABLE ADD CONSTRAINT USING INDEX, look up the index and
     * verify it's usable, then extract the implied column name list.  (We
     * will not actually need the column name list at runtime, but we need it
     * now to check for duplicate column entries below.)
     */
    if (constraint->indexname != NULL)
    {
        char       *index_name = constraint->indexname;
        Relation    heap_rel = cxt->rel;
        Oid         index_oid;
        Relation    index_rel;
        Form_pg_index index_form;
        oidvector  *indclass;
        Datum       indclassDatum;
        bool        isnull;
        int         i;

        /* Grammar should not allow this with explicit column list */
        Assert(constraint->keys == NIL);

        /* Grammar should only allow PRIMARY and UNIQUE constraints */
        Assert(constraint->contype == CONSTR_PRIMARY ||
               constraint->contype == CONSTR_UNIQUE);

        /* Must be ALTER, not CREATE, but grammar doesn't enforce that */
        if (!cxt->isalter)
            ereport(ERROR,
                    (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                     errmsg("cannot use an existing index in CREATE TABLE"),
                     parser_errposition(cxt->pstate, constraint->location)));

        /* Look for the index in the same schema as the table */
        index_oid = get_relname_relid(index_name, RelationGetNamespace(heap_rel));

        if (!OidIsValid(index_oid))
            ereport(ERROR,
                    (errcode(ERRCODE_UNDEFINED_OBJECT),
                     errmsg("index \"%s\" does not exist", index_name),
                     parser_errposition(cxt->pstate, constraint->location)));

        /* Open the index (this will throw an error if it is not an index) */
        index_rel = index_open(index_oid, AccessShareLock);
        index_form = index_rel->rd_index;

        /* Check that it does not have an associated constraint already */
        if (OidIsValid(get_index_constraint(index_oid)))
            ereport(ERROR,
                    (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
               errmsg("index \"%s\" is already associated with a constraint",
                      index_name),
                     parser_errposition(cxt->pstate, constraint->location)));

        /* Perform validity checks on the index */
        if (index_form->indrelid != RelationGetRelid(heap_rel))
            ereport(ERROR,
                    (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
                     errmsg("index \"%s\" does not belong to table \"%s\"",
                            index_name, RelationGetRelationName(heap_rel)),
                     parser_errposition(cxt->pstate, constraint->location)));

        if (!index_form->indisvalid)
            ereport(ERROR,
                    (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
                     errmsg("index \"%s\" is not valid", index_name),
                     parser_errposition(cxt->pstate, constraint->location)));

        if (!index_form->indisready)
            ereport(ERROR,
                    (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
                     errmsg("index \"%s\" is not ready", index_name),
                     parser_errposition(cxt->pstate, constraint->location)));

        if (!index_form->indisunique)
            ereport(ERROR,
                    (errcode(ERRCODE_WRONG_OBJECT_TYPE),
                     errmsg("\"%s\" is not a unique index", index_name),
                     errdetail("Cannot create a primary key or unique constraint using such an index."),
                     parser_errposition(cxt->pstate, constraint->location)));

        if (RelationGetIndexExpressions(index_rel) != NIL)
            ereport(ERROR,
                    (errcode(ERRCODE_WRONG_OBJECT_TYPE),
                     errmsg("index \"%s\" contains expressions", index_name),
                     errdetail("Cannot create a primary key or unique constraint using such an index."),
                     parser_errposition(cxt->pstate, constraint->location)));

        if (RelationGetIndexPredicate(index_rel) != NIL)
            ereport(ERROR,
                    (errcode(ERRCODE_WRONG_OBJECT_TYPE),
                     errmsg("\"%s\" is a partial index", index_name),
                     errdetail("Cannot create a primary key or unique constraint using such an index."),
                     parser_errposition(cxt->pstate, constraint->location)));

        /*
         * It's probably unsafe to change a deferred index to non-deferred. (A
         * non-constraint index couldn't be deferred anyway, so this case
         * should never occur; no need to sweat, but let's check it.)
         */
        if (!index_form->indimmediate && !constraint->deferrable)
            ereport(ERROR,
                    (errcode(ERRCODE_WRONG_OBJECT_TYPE),
                     errmsg("\"%s\" is a deferrable index", index_name),
                     errdetail("Cannot create a non-deferrable constraint using a deferrable index."),
                     parser_errposition(cxt->pstate, constraint->location)));

        /*
         * Insist on it being a btree.  That's the only kind that supports
         * uniqueness at the moment anyway; but we must have an index that
         * exactly matches what you'd get from plain ADD CONSTRAINT syntax,
         * else dump and reload will produce a different index (breaking
         * pg_upgrade in particular).
         */
        if (index_rel->rd_rel->relam != get_am_oid(DEFAULT_INDEX_TYPE, false))
            ereport(ERROR,
                    (errcode(ERRCODE_WRONG_OBJECT_TYPE),
                     errmsg("index \"%s\" is not a btree", index_name),
                     parser_errposition(cxt->pstate, constraint->location)));

        /* Must get indclass the hard way */
        indclassDatum = SysCacheGetAttr(INDEXRELID, index_rel->rd_indextuple,
                                        Anum_pg_index_indclass, &isnull);
        Assert(!isnull);
        indclass = (oidvector *) DatumGetPointer(indclassDatum);

        for (i = 0; i < index_form->indnatts; i++)
        {
            int16       attnum = index_form->indkey.values[i];
            Form_pg_attribute attform;
            char       *attname;
            Oid         defopclass;

            /*
             * We shouldn't see attnum == 0 here, since we already rejected
             * expression indexes.  If we do, SystemAttributeDefinition will
             * throw an error.
             */
            if (attnum > 0)
            {
                Assert(attnum <= heap_rel->rd_att->natts);
                attform = heap_rel->rd_att->attrs[attnum - 1];
            }
            else
                attform = SystemAttributeDefinition(attnum,
                                               heap_rel->rd_rel->relhasoids);
            attname = pstrdup(NameStr(attform->attname));

            /*
             * Insist on default opclass and sort options.  While the index
             * would still work as a constraint with non-default settings, it
             * might not provide exactly the same uniqueness semantics as
             * you'd get from a normally-created constraint; and there's also
             * the dump/reload problem mentioned above.
             */
            defopclass = GetDefaultOpClass(attform->atttypid,
                                           index_rel->rd_rel->relam);
            if (indclass->values[i] != defopclass ||
                index_rel->rd_indoption[i] != 0)
                ereport(ERROR,
                        (errcode(ERRCODE_WRONG_OBJECT_TYPE),
                         errmsg("index \"%s\" does not have default sorting behavior", index_name),
                         errdetail("Cannot create a primary key or unique constraint using such an index."),
                     parser_errposition(cxt->pstate, constraint->location)));

            constraint->keys = lappend(constraint->keys, makeString(attname));
        }

        /* Close the index relation but keep the lock */
        relation_close(index_rel, NoLock);

        index->indexOid = index_oid;
    }

    /*
     * If it's an EXCLUDE constraint, the grammar returns a list of pairs of
     * IndexElems and operator names.  We have to break that apart into
     * separate lists.
     */
    if (constraint->contype == CONSTR_EXCLUSION)
    {
        foreach(lc, constraint->exclusions)
        {
            List       *pair = (List *) lfirst(lc);
            IndexElem  *elem;
            List       *opname;

            Assert(list_length(pair) == 2);
            elem = (IndexElem *) linitial(pair);
            Assert(IsA(elem, IndexElem));
            opname = (List *) lsecond(pair);
            Assert(IsA(opname, List));

            index->indexParams = lappend(index->indexParams, elem);
            index->excludeOpNames = lappend(index->excludeOpNames, opname);
        }

        return index;
    }

    /*
     * For UNIQUE and PRIMARY KEY, we just have a list of column names.
     *
     * Make sure referenced keys exist.  If we are making a PRIMARY KEY index,
     * also make sure they are NOT NULL, if possible. (Although we could leave
     * it to DefineIndex to mark the columns NOT NULL, it's more efficient to
     * get it right the first time.)
     */
    foreach(lc, constraint->keys)
    {
        char       *key = strVal(lfirst(lc));
        bool        found = false;
        ColumnDef  *column = NULL;
        ListCell   *columns;
        IndexElem  *iparam;

        foreach(columns, cxt->columns)
        {
            column = (ColumnDef *) lfirst(columns);
            Assert(IsA(column, ColumnDef));
            if (strcmp(column->colname, key) == 0)
            {
                found = true;
                break;
            }
        }
        if (found)
        {
            /* found column in the new table; force it to be NOT NULL */
            if (constraint->contype == CONSTR_PRIMARY)
                column->is_not_null = TRUE;
        }
        else if (SystemAttributeByName(key, cxt->hasoids) != NULL)
        {
            /*
             * column will be a system column in the new table, so accept it.
             * System columns can't ever be null, so no need to worry about
             * PRIMARY/NOT NULL constraint.
             */
            found = true;
        }
        else if (cxt->inhRelations)
        {
            /* try inherited tables */
            ListCell   *inher;

            foreach(inher, cxt->inhRelations)
            {
                RangeVar   *inh = (RangeVar *) lfirst(inher);
                Relation    rel;
                int         count;

                Assert(IsA(inh, RangeVar));
                rel = heap_openrv(inh, AccessShareLock);
                if (rel->rd_rel->relkind != RELKIND_RELATION)
                    ereport(ERROR,
                            (errcode(ERRCODE_WRONG_OBJECT_TYPE),
                           errmsg("inherited relation \"%s\" is not a table",
                                  inh->relname)));
                for (count = 0; count < rel->rd_att->natts; count++)
                {
                    Form_pg_attribute inhattr = rel->rd_att->attrs[count];
                    char       *inhname = NameStr(inhattr->attname);

                    if (inhattr->attisdropped)
                        continue;
                    if (strcmp(key, inhname) == 0)
                    {
                        found = true;

                        /*
                         * We currently have no easy way to force an inherited
                         * column to be NOT NULL at creation, if its parent
                         * wasn't so already. We leave it to DefineIndex to
                         * fix things up in this case.
                         */
                        break;
                    }
                }
                heap_close(rel, NoLock);
                if (found)
                    break;
            }
        }

        /*
         * In the ALTER TABLE case, don't complain about index keys not
         * created in the command; they may well exist already. DefineIndex
         * will complain about them if not, and will also take care of marking
         * them NOT NULL.
         */
        if (!found && !cxt->isalter)
            ereport(ERROR,
                    (errcode(ERRCODE_UNDEFINED_COLUMN),
                     errmsg("column \"%s\" named in key does not exist", key),
                     parser_errposition(cxt->pstate, constraint->location)));

        /* Check for PRIMARY KEY(foo, foo) */
        foreach(columns, index->indexParams)
        {
            iparam = (IndexElem *) lfirst(columns);
            if (iparam->name && strcmp(key, iparam->name) == 0)
            {
                if (index->primary)
                    ereport(ERROR,
                            (errcode(ERRCODE_DUPLICATE_COLUMN),
                             errmsg("column \"%s\" appears twice in primary key constraint",
                                    key),
                     parser_errposition(cxt->pstate, constraint->location)));
                else
                    ereport(ERROR,
                            (errcode(ERRCODE_DUPLICATE_COLUMN),
                    errmsg("column \"%s\" appears twice in unique constraint",
                           key),
                     parser_errposition(cxt->pstate, constraint->location)));
            }
        }

        /* OK, add it to the index definition */
        iparam = makeNode(IndexElem);
        iparam->name = pstrdup(key);
        iparam->expr = NULL;
        iparam->indexcolname = NULL;
        iparam->collation = NIL;
        iparam->opclass = NIL;
        iparam->ordering = SORTBY_DEFAULT;
        iparam->nulls_ordering = SORTBY_NULLS_DEFAULT;
        index->indexParams = lappend(index->indexParams, iparam);
    }

    return index;
}

/*
 * transformFKConstraints
 *      handle FOREIGN KEY constraints
 */
static void
transformFKConstraints(CreateStmtContext *cxt,
                       bool skipValidation, bool isAddConstraint)
{
    ListCell   *fkclist;

    if (cxt->fkconstraints == NIL)
        return;

    /*
     * If CREATE TABLE or adding a column with NULL default, we can safely
     * skip validation of FK constraints, and nonetheless mark them valid.
     * (This will override any user-supplied NOT VALID flag.)
     */
    if (skipValidation)
    {
        foreach(fkclist, cxt->fkconstraints)
        {
            Constraint *constraint = (Constraint *) lfirst(fkclist);

            constraint->skip_validation = true;
            constraint->initially_valid = true;
        }
    }

    /*
     * For CREATE TABLE or ALTER TABLE ADD COLUMN, gin up an ALTER TABLE ADD
     * CONSTRAINT command to execute after the basic command is complete. (If
     * called from ADD CONSTRAINT, that routine will add the FK constraints to
     * its own subcommand list.)
     *
     * Note: the ADD CONSTRAINT command must also execute after any index
     * creation commands.  Thus, this should run after
     * transformIndexConstraints, so that the CREATE INDEX commands are
     * already in cxt->alist.
     */
    if (!isAddConstraint)
    {
        AlterTableStmt *alterstmt = makeNode(AlterTableStmt);

        alterstmt->relation = cxt->relation;
        alterstmt->cmds = NIL;
        alterstmt->relkind = OBJECT_TABLE;

        foreach(fkclist, cxt->fkconstraints)
        {
            Constraint *constraint = (Constraint *) lfirst(fkclist);
            AlterTableCmd *altercmd = makeNode(AlterTableCmd);

            altercmd->subtype = AT_ProcessedConstraint;
            altercmd->name = NULL;
            altercmd->def = (Node *) constraint;
            alterstmt->cmds = lappend(alterstmt->cmds, altercmd);
        }

        cxt->alist = lappend(cxt->alist, alterstmt);
    }
}

/*
 * transformIndexStmt - parse analysis for CREATE INDEX and ALTER TABLE
 *
 * Note: this is a no-op for an index not using either index expressions or
 * a predicate expression.  There are several code paths that create indexes
 * without bothering to call this, because they know they don't have any
 * such expressions to deal with.
 */
IndexStmt *
transformIndexStmt(IndexStmt *stmt, const char *queryString)
{
    Relation    rel;
    ParseState *pstate;
    RangeTblEntry *rte;
    ListCell   *l;

    /*
     * We must not scribble on the passed-in IndexStmt, so copy it.  (This is
     * overkill, but easy.)
     */
    stmt = (IndexStmt *) copyObject(stmt);

    /*
     * Open the parent table with appropriate locking.  We must do this
     * because addRangeTableEntry() would acquire only AccessShareLock,
     * leaving DefineIndex() needing to do a lock upgrade with consequent risk
     * of deadlock.  Make sure this stays in sync with the type of lock
     * DefineIndex() wants. If we are being called by ALTER TABLE, we will
     * already hold a higher lock.
     */
    rel = heap_openrv(stmt->relation,
                  (stmt->concurrent ? ShareUpdateExclusiveLock : ShareLock));

    /* Set up pstate */
    pstate = make_parsestate(NULL);
    pstate->p_sourcetext = queryString;

    /*
     * Put the parent table into the rtable so that the expressions can refer
     * to its fields without qualification.
     */
    rte = addRangeTableEntry(pstate, stmt->relation, NULL, false, true);

    /* no to join list, yes to namespaces */
    addRTEtoQuery(pstate, rte, false, true, true);

    /* take care of the where clause */
    if (stmt->whereClause)
    {
        stmt->whereClause = transformWhereClause(pstate,
                                                 stmt->whereClause,
                                                 "WHERE");
        /* we have to fix its collations too */
        assign_expr_collations(pstate, stmt->whereClause);
    }

    /* take care of any index expressions */
    foreach(l, stmt->indexParams)
    {
        IndexElem  *ielem = (IndexElem *) lfirst(l);

        if (ielem->expr)
        {
            /* Extract preliminary index col name before transforming expr */
            if (ielem->indexcolname == NULL)
                ielem->indexcolname = FigureIndexColname(ielem->expr);

            /* Now do parse transformation of the expression */
            ielem->expr = transformExpr(pstate, ielem->expr);

            /* We have to fix its collations too */
            assign_expr_collations(pstate, ielem->expr);

            /*
             * We check only that the result type is legitimate; this is for
             * consistency with what transformWhereClause() checks for the
             * predicate.  DefineIndex() will make more checks.
             */
            if (expression_returns_set(ielem->expr))
                ereport(ERROR,
                        (errcode(ERRCODE_DATATYPE_MISMATCH),
                         errmsg("index expression cannot return a set")));
        }
    }

    /*
     * Check that only the base rel is mentioned.
     */
    if (list_length(pstate->p_rtable) != 1)
        ereport(ERROR,
                (errcode(ERRCODE_INVALID_COLUMN_REFERENCE),
                 errmsg("index expressions and predicates can refer only to the table being indexed")));

    free_parsestate(pstate);

    /* Close relation, but keep the lock */
    heap_close(rel, NoLock);

    return stmt;
}


/*
 * transformRuleStmt -
 *    transform a CREATE RULE Statement. The action is a list of parse
 *    trees which is transformed into a list of query trees, and we also
 *    transform the WHERE clause if any.
 *
 * actions and whereClause are output parameters that receive the
 * transformed results.
 *
 * Note that we must not scribble on the passed-in RuleStmt, so we do
 * copyObject() on the actions and WHERE clause.
 */
void
transformRuleStmt(RuleStmt *stmt, const char *queryString,
                  List **actions, Node **whereClause)
{
    Relation    rel;
    ParseState *pstate;
    RangeTblEntry *oldrte;
    RangeTblEntry *newrte;

    /*
     * To avoid deadlock, make sure the first thing we do is grab
     * AccessExclusiveLock on the target relation.  This will be needed by
     * DefineQueryRewrite(), and we don't want to grab a lesser lock
     * beforehand.
     */
    rel = heap_openrv(stmt->relation, AccessExclusiveLock);

    /* Set up pstate */
    pstate = make_parsestate(NULL);
    pstate->p_sourcetext = queryString;

    /*
     * NOTE: 'OLD' must always have a varno equal to 1 and 'NEW' equal to 2.
     * Set up their RTEs in the main pstate for use in parsing the rule
     * qualification.
     */
    oldrte = addRangeTableEntryForRelation(pstate, rel,
                                           makeAlias("old", NIL),
                                           false, false);
    newrte = addRangeTableEntryForRelation(pstate, rel,
                                           makeAlias("new", NIL),
                                           false, false);
    /* Must override addRangeTableEntry's default access-check flags */
    oldrte->requiredPerms = 0;
    newrte->requiredPerms = 0;

    /*
     * They must be in the namespace too for lookup purposes, but only add the
     * one(s) that are relevant for the current kind of rule.  In an UPDATE
     * rule, quals must refer to OLD.field or NEW.field to be unambiguous, but
     * there's no need to be so picky for INSERT & DELETE.  We do not add them
     * to the joinlist.
     */
    switch (stmt->event)
    {
        case CMD_SELECT:
            addRTEtoQuery(pstate, oldrte, false, true, true);
            break;
        case CMD_UPDATE:
            addRTEtoQuery(pstate, oldrte, false, true, true);
            addRTEtoQuery(pstate, newrte, false, true, true);
            break;
        case CMD_INSERT:
            addRTEtoQuery(pstate, newrte, false, true, true);
            break;
        case CMD_DELETE:
            addRTEtoQuery(pstate, oldrte, false, true, true);
            break;
        default:
            elog(ERROR, "unrecognized event type: %d",
                 (int) stmt->event);
            break;
    }

    /* take care of the where clause */
    *whereClause = transformWhereClause(pstate,
                                      (Node *) copyObject(stmt->whereClause),
                                        "WHERE");
    /* we have to fix its collations too */
    assign_expr_collations(pstate, *whereClause);

    if (list_length(pstate->p_rtable) != 2)     /* naughty, naughty... */
        ereport(ERROR,
                (errcode(ERRCODE_INVALID_OBJECT_DEFINITION),
                 errmsg("rule WHERE condition cannot contain references to other relations")));

    /* aggregates not allowed (but subselects are okay) */
    if (pstate->p_hasAggs)
        ereport(ERROR,
                (errcode(ERRCODE_GROUPING_ERROR),
           errmsg("cannot use aggregate function in rule WHERE condition")));
    if (pstate->p_hasWindowFuncs)
        ereport(ERROR,
                (errcode(ERRCODE_WINDOWING_ERROR),
              errmsg("cannot use window function in rule WHERE condition")));

    /*
     * 'instead nothing' rules with a qualification need a query rangetable so
     * the rewrite handler can add the negated rule qualification to the
     * original query. We create a query with the new command type CMD_NOTHING
     * here that is treated specially by the rewrite system.
     */
    if (stmt->actions == NIL)
    {
        Query      *nothing_qry = makeNode(Query);

        nothing_qry->commandType = CMD_NOTHING;
        nothing_qry->rtable = pstate->p_rtable;
        nothing_qry->jointree = makeFromExpr(NIL, NULL);        /* no join wanted */

        *actions = list_make1(nothing_qry);
    }
    else
    {
        ListCell   *l;
        List       *newactions = NIL;

        /*
         * transform each statement, like parse_sub_analyze()
         */
        foreach(l, stmt->actions)
        {
            Node       *action = (Node *) lfirst(l);
            ParseState *sub_pstate = make_parsestate(NULL);
            Query      *sub_qry,
                       *top_subqry;
            bool        has_old,
                        has_new;

            /*
             * Since outer ParseState isn't parent of inner, have to pass down
             * the query text by hand.
             */
            sub_pstate->p_sourcetext = queryString;

            /*
             * Set up OLD/NEW in the rtable for this statement.  The entries
             * are added only to relnamespace, not varnamespace, because we
             * don't want them to be referred to by unqualified field names
             * nor "*" in the rule actions.  We decide later whether to put
             * them in the joinlist.
             */
            oldrte = addRangeTableEntryForRelation(sub_pstate, rel,
                                                   makeAlias("old", NIL),
                                                   false, false);
            newrte = addRangeTableEntryForRelation(sub_pstate, rel,
                                                   makeAlias("new", NIL),
                                                   false, false);
            oldrte->requiredPerms = 0;
            newrte->requiredPerms = 0;
            addRTEtoQuery(sub_pstate, oldrte, false, true, false);
            addRTEtoQuery(sub_pstate, newrte, false, true, false);

            /* Transform the rule action statement */
            top_subqry = transformStmt(sub_pstate,
                                       (Node *) copyObject(action));

            /*
             * We cannot support utility-statement actions (eg NOTIFY) with
             * nonempty rule WHERE conditions, because there's no way to make
             * the utility action execute conditionally.
             */
            if (top_subqry->commandType == CMD_UTILITY &&
                *whereClause != NULL)
                ereport(ERROR,
                        (errcode(ERRCODE_INVALID_OBJECT_DEFINITION),
                         errmsg("rules with WHERE conditions can only have SELECT, INSERT, UPDATE, or DELETE actions")));

            /*
             * If the action is INSERT...SELECT, OLD/NEW have been pushed down
             * into the SELECT, and that's what we need to look at. (Ugly
             * kluge ... try to fix this when we redesign querytrees.)
             */
            sub_qry = getInsertSelectQuery(top_subqry, NULL);

            /*
             * If the sub_qry is a setop, we cannot attach any qualifications
             * to it, because the planner won't notice them.  This could
             * perhaps be relaxed someday, but for now, we may as well reject
             * such a rule immediately.
             */
            if (sub_qry->setOperations != NULL && *whereClause != NULL)
                ereport(ERROR,
                        (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                         errmsg("conditional UNION/INTERSECT/EXCEPT statements are not implemented")));

            /*
             * Validate action's use of OLD/NEW, qual too
             */
            has_old =
                rangeTableEntry_used((Node *) sub_qry, PRS2_OLD_VARNO, 0) ||
                rangeTableEntry_used(*whereClause, PRS2_OLD_VARNO, 0);
            has_new =
                rangeTableEntry_used((Node *) sub_qry, PRS2_NEW_VARNO, 0) ||
                rangeTableEntry_used(*whereClause, PRS2_NEW_VARNO, 0);

            switch (stmt->event)
            {
                case CMD_SELECT:
                    if (has_old)
                        ereport(ERROR,
                                (errcode(ERRCODE_INVALID_OBJECT_DEFINITION),
                                 errmsg("ON SELECT rule cannot use OLD")));
                    if (has_new)
                        ereport(ERROR,
                                (errcode(ERRCODE_INVALID_OBJECT_DEFINITION),
                                 errmsg("ON SELECT rule cannot use NEW")));
                    break;
                case CMD_UPDATE:
                    /* both are OK */
                    break;
                case CMD_INSERT:
                    if (has_old)
                        ereport(ERROR,
                                (errcode(ERRCODE_INVALID_OBJECT_DEFINITION),
                                 errmsg("ON INSERT rule cannot use OLD")));
                    break;
                case CMD_DELETE:
                    if (has_new)
                        ereport(ERROR,
                                (errcode(ERRCODE_INVALID_OBJECT_DEFINITION),
                                 errmsg("ON DELETE rule cannot use NEW")));
                    break;
                default:
                    elog(ERROR, "unrecognized event type: %d",
                         (int) stmt->event);
                    break;
            }

            /*
             * OLD/NEW are not allowed in WITH queries, because they would
             * amount to outer references for the WITH, which we disallow.
             * However, they were already in the outer rangetable when we
             * analyzed the query, so we have to check.
             *
             * Note that in the INSERT...SELECT case, we need to examine the
             * CTE lists of both top_subqry and sub_qry.
             *
             * Note that we aren't digging into the body of the query looking
             * for WITHs in nested sub-SELECTs.  A WITH down there can
             * legitimately refer to OLD/NEW, because it'd be an
             * indirect-correlated outer reference.
             */
            if (rangeTableEntry_used((Node *) top_subqry->cteList,
                                     PRS2_OLD_VARNO, 0) ||
                rangeTableEntry_used((Node *) sub_qry->cteList,
                                     PRS2_OLD_VARNO, 0))
                ereport(ERROR,
                        (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                         errmsg("cannot refer to OLD within WITH query")));
            if (rangeTableEntry_used((Node *) top_subqry->cteList,
                                     PRS2_NEW_VARNO, 0) ||
                rangeTableEntry_used((Node *) sub_qry->cteList,
                                     PRS2_NEW_VARNO, 0))
                ereport(ERROR,
                        (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                         errmsg("cannot refer to NEW within WITH query")));

            /*
             * For efficiency's sake, add OLD to the rule action's jointree
             * only if it was actually referenced in the statement or qual.
             *
             * For INSERT, NEW is not really a relation (only a reference to
             * the to-be-inserted tuple) and should never be added to the
             * jointree.
             *
             * For UPDATE, we treat NEW as being another kind of reference to
             * OLD, because it represents references to *transformed* tuples
             * of the existing relation.  It would be wrong to enter NEW
             * separately in the jointree, since that would cause a double
             * join of the updated relation.  It's also wrong to fail to make
             * a jointree entry if only NEW and not OLD is mentioned.
             */
            if (has_old || (has_new && stmt->event == CMD_UPDATE))
            {
                /*
                 * If sub_qry is a setop, manipulating its jointree will do no
                 * good at all, because the jointree is dummy. (This should be
                 * a can't-happen case because of prior tests.)
                 */
                if (sub_qry->setOperations != NULL)
                    ereport(ERROR,
                            (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                             errmsg("conditional UNION/INTERSECT/EXCEPT statements are not implemented")));
                /* hack so we can use addRTEtoQuery() */
                sub_pstate->p_rtable = sub_qry->rtable;
                sub_pstate->p_joinlist = sub_qry->jointree->fromlist;
                addRTEtoQuery(sub_pstate, oldrte, true, false, false);
                sub_qry->jointree->fromlist = sub_pstate->p_joinlist;
            }

            newactions = lappend(newactions, top_subqry);

            free_parsestate(sub_pstate);
        }

        *actions = newactions;
    }

    free_parsestate(pstate);

    /* Close relation, but keep the exclusive lock */
    heap_close(rel, NoLock);
}


/*
 * transformAlterTableStmt -
 *      parse analysis for ALTER TABLE
 *
 * Returns a List of utility commands to be done in sequence.  One of these
 * will be the transformed AlterTableStmt, but there may be additional actions
 * to be done before and after the actual AlterTable() call.
 */
List *
transformAlterTableStmt(AlterTableStmt *stmt, const char *queryString)
{
    Relation    rel;
    ParseState *pstate;
    CreateStmtContext cxt;
    List       *result;
    List       *save_alist;
    ListCell   *lcmd,
               *l;
    List       *newcmds = NIL;
    bool        skipValidation = true;
    AlterTableCmd *newcmd;
    LOCKMODE    lockmode;

    /*
     * We must not scribble on the passed-in AlterTableStmt, so copy it. (This
     * is overkill, but easy.)
     */
    stmt = (AlterTableStmt *) copyObject(stmt);

    /*
     * Determine the appropriate lock level for this list of subcommands.
     */
    lockmode = AlterTableGetLockLevel(stmt->cmds);

    /*
     * Acquire appropriate lock on the target relation, which will be held
     * until end of transaction.  This ensures any decisions we make here
     * based on the state of the relation will still be good at execution. We
     * must get lock now because execution will later require it; taking a
     * lower grade lock now and trying to upgrade later risks deadlock.  Any
     * new commands we add after this must not upgrade the lock level
     * requested here.
     */
    rel = relation_openrv_extended(stmt->relation, lockmode, stmt->missing_ok);
    if (rel == NULL)
    {
        /* this message is consistent with relation_openrv */
        ereport(NOTICE,
                (errmsg("relation \"%s\" does not exist, skipping",
                        stmt->relation->relname)));
        return NIL;
    }

    /* Set up pstate and CreateStmtContext */
    pstate = make_parsestate(NULL);
    pstate->p_sourcetext = queryString;

    cxt.pstate = pstate;
    cxt.stmtType = "ALTER TABLE";
    cxt.relation = stmt->relation;
    cxt.rel = rel;
    cxt.inhRelations = NIL;
    cxt.isalter = true;
    cxt.hasoids = false;        /* need not be right */
    cxt.columns = NIL;
    cxt.ckconstraints = NIL;
    cxt.fkconstraints = NIL;
    cxt.ixconstraints = NIL;
    cxt.inh_indexes = NIL;
    cxt.blist = NIL;
    cxt.alist = NIL;
    cxt.pkey = NULL;

    /*
     * The only subtypes that currently require parse transformation handling
     * are ADD COLUMN and ADD CONSTRAINT.  These largely re-use code from
     * CREATE TABLE.
     */
    foreach(lcmd, stmt->cmds)
    {
        AlterTableCmd *cmd = (AlterTableCmd *) lfirst(lcmd);

        switch (cmd->subtype)
        {
            case AT_AddColumn:
            case AT_AddColumnToView:
                {
                    ColumnDef  *def = (ColumnDef *) cmd->def;

                    Assert(IsA(def, ColumnDef));
                    transformColumnDefinition(&cxt, def);

                    /*
                     * If the column has a non-null default, we can't skip
                     * validation of foreign keys.
                     */
                    if (def->raw_default != NULL)
                        skipValidation = false;

                    /*
                     * All constraints are processed in other ways. Remove the
                     * original list
                     */
                    def->constraints = NIL;

                    newcmds = lappend(newcmds, cmd);
                    break;
                }
            case AT_AddConstraint:

                /*
                 * The original AddConstraint cmd node doesn't go to newcmds
                 */
                if (IsA(cmd->def, Constraint))
                {
                    transformTableConstraint(&cxt, (Constraint *) cmd->def);
                    if (((Constraint *) cmd->def)->contype == CONSTR_FOREIGN)
                        skipValidation = false;
                }
                else
                    elog(ERROR, "unrecognized node type: %d",
                         (int) nodeTag(cmd->def));
                break;

            case AT_ProcessedConstraint:

                /*
                 * Already-transformed ADD CONSTRAINT, so just make it look
                 * like the standard case.
                 */
                cmd->subtype = AT_AddConstraint;
                newcmds = lappend(newcmds, cmd);
                break;

            default:
                newcmds = lappend(newcmds, cmd);
                break;
        }
    }

    /*
     * transformIndexConstraints wants cxt.alist to contain only index
     * statements, so transfer anything we already have into save_alist
     * immediately.
     */
    save_alist = cxt.alist;
    cxt.alist = NIL;

    /* Postprocess index and FK constraints */
    transformIndexConstraints(&cxt);

    transformFKConstraints(&cxt, skipValidation, true);

    /*
     * Push any index-creation commands into the ALTER, so that they can be
     * scheduled nicely by tablecmds.c.  Note that tablecmds.c assumes that
     * the IndexStmt attached to an AT_AddIndex or AT_AddIndexConstraint
     * subcommand has already been through transformIndexStmt.
     */
    foreach(l, cxt.alist)
    {
        IndexStmt  *idxstmt = (IndexStmt *) lfirst(l);

        Assert(IsA(idxstmt, IndexStmt));
        idxstmt = transformIndexStmt(idxstmt, queryString);
        newcmd = makeNode(AlterTableCmd);
        newcmd->subtype = OidIsValid(idxstmt->indexOid) ? AT_AddIndexConstraint : AT_AddIndex;
        newcmd->def = (Node *) idxstmt;
        newcmds = lappend(newcmds, newcmd);
    }
    cxt.alist = NIL;

    /* Append any CHECK or FK constraints to the commands list */
    foreach(l, cxt.ckconstraints)
    {
        newcmd = makeNode(AlterTableCmd);
        newcmd->subtype = AT_AddConstraint;
        newcmd->def = (Node *) lfirst(l);
        newcmds = lappend(newcmds, newcmd);
    }
    foreach(l, cxt.fkconstraints)
    {
        newcmd = makeNode(AlterTableCmd);
        newcmd->subtype = AT_AddConstraint;
        newcmd->def = (Node *) lfirst(l);
        newcmds = lappend(newcmds, newcmd);
    }

    /* Close rel but keep lock */
    relation_close(rel, NoLock);

    /*
     * Output results.
     */
    stmt->cmds = newcmds;

    result = lappend(cxt.blist, stmt);
    result = list_concat(result, cxt.alist);
    result = list_concat(result, save_alist);

    return result;
}


/*
 * Preprocess a list of column constraint clauses
 * to attach constraint attributes to their primary constraint nodes
 * and detect inconsistent/misplaced constraint attributes.
 *
 * NOTE: currently, attributes are only supported for FOREIGN KEY, UNIQUE,
 * EXCLUSION, and PRIMARY KEY constraints, but someday they ought to be
 * supported for other constraint types.
 */
static void
transformConstraintAttrs(CreateStmtContext *cxt, List *constraintList)
{
    Constraint *lastprimarycon = NULL;
    bool        saw_deferrability = false;
    bool        saw_initially = false;
    ListCell   *clist;

#define SUPPORTS_ATTRS(node)                \
    ((node) != NULL &&                      \
     ((node)->contype == CONSTR_PRIMARY ||  \
      (node)->contype == CONSTR_UNIQUE ||   \
      (node)->contype == CONSTR_EXCLUSION || \
      (node)->contype == CONSTR_FOREIGN))

    foreach(clist, constraintList)
    {
        Constraint *con = (Constraint *) lfirst(clist);

        if (!IsA(con, Constraint))
            elog(ERROR, "unrecognized node type: %d",
                 (int) nodeTag(con));
        switch (con->contype)
        {
            case CONSTR_ATTR_DEFERRABLE:
                if (!SUPPORTS_ATTRS(lastprimarycon))
                    ereport(ERROR,
                            (errcode(ERRCODE_SYNTAX_ERROR),
                             errmsg("misplaced DEFERRABLE clause"),
                             parser_errposition(cxt->pstate, con->location)));
                if (saw_deferrability)
                    ereport(ERROR,
                            (errcode(ERRCODE_SYNTAX_ERROR),
                             errmsg("multiple DEFERRABLE/NOT DEFERRABLE clauses not allowed"),
                             parser_errposition(cxt->pstate, con->location)));
                saw_deferrability = true;
                lastprimarycon->deferrable = true;
                break;

            case CONSTR_ATTR_NOT_DEFERRABLE:
                if (!SUPPORTS_ATTRS(lastprimarycon))
                    ereport(ERROR,
                            (errcode(ERRCODE_SYNTAX_ERROR),
                             errmsg("misplaced NOT DEFERRABLE clause"),
                             parser_errposition(cxt->pstate, con->location)));
                if (saw_deferrability)
                    ereport(ERROR,
                            (errcode(ERRCODE_SYNTAX_ERROR),
                             errmsg("multiple DEFERRABLE/NOT DEFERRABLE clauses not allowed"),
                             parser_errposition(cxt->pstate, con->location)));
                saw_deferrability = true;
                lastprimarycon->deferrable = false;
                if (saw_initially &&
                    lastprimarycon->initdeferred)
                    ereport(ERROR,
                            (errcode(ERRCODE_SYNTAX_ERROR),
                             errmsg("constraint declared INITIALLY DEFERRED must be DEFERRABLE"),
                             parser_errposition(cxt->pstate, con->location)));
                break;

            case CONSTR_ATTR_DEFERRED:
                if (!SUPPORTS_ATTRS(lastprimarycon))
                    ereport(ERROR,
                            (errcode(ERRCODE_SYNTAX_ERROR),
                             errmsg("misplaced INITIALLY DEFERRED clause"),
                             parser_errposition(cxt->pstate, con->location)));
                if (saw_initially)
                    ereport(ERROR,
                            (errcode(ERRCODE_SYNTAX_ERROR),
                             errmsg("multiple INITIALLY IMMEDIATE/DEFERRED clauses not allowed"),
                             parser_errposition(cxt->pstate, con->location)));
                saw_initially = true;
                lastprimarycon->initdeferred = true;

                /*
                 * If only INITIALLY DEFERRED appears, assume DEFERRABLE
                 */
                if (!saw_deferrability)
                    lastprimarycon->deferrable = true;
                else if (!lastprimarycon->deferrable)
                    ereport(ERROR,
                            (errcode(ERRCODE_SYNTAX_ERROR),
                             errmsg("constraint declared INITIALLY DEFERRED must be DEFERRABLE"),
                             parser_errposition(cxt->pstate, con->location)));
                break;

            case CONSTR_ATTR_IMMEDIATE:
                if (!SUPPORTS_ATTRS(lastprimarycon))
                    ereport(ERROR,
                            (errcode(ERRCODE_SYNTAX_ERROR),
                             errmsg("misplaced INITIALLY IMMEDIATE clause"),
                             parser_errposition(cxt->pstate, con->location)));
                if (saw_initially)
                    ereport(ERROR,
                            (errcode(ERRCODE_SYNTAX_ERROR),
                             errmsg("multiple INITIALLY IMMEDIATE/DEFERRED clauses not allowed"),
                             parser_errposition(cxt->pstate, con->location)));
                saw_initially = true;
                lastprimarycon->initdeferred = false;
                break;

            default:
                /* Otherwise it's not an attribute */
                lastprimarycon = con;
                /* reset flags for new primary node */
                saw_deferrability = false;
                saw_initially = false;
                break;
        }
    }
}

/*
 * Special handling of type definition for a column
 */
static void
transformColumnType(CreateStmtContext *cxt, ColumnDef *column)
{
    /*
     * All we really need to do here is verify that the type is valid,
     * including any collation spec that might be present.
     */
    Type        ctype = typenameType(cxt->pstate, column->typeName, NULL);

    if (column->collClause)
    {
        Form_pg_type typtup = (Form_pg_type) GETSTRUCT(ctype);

        LookupCollation(cxt->pstate,
                        column->collClause->collname,
                        column->collClause->location);
        /* Complain if COLLATE is applied to an uncollatable type */
        if (!OidIsValid(typtup->typcollation))
            ereport(ERROR,
                    (errcode(ERRCODE_DATATYPE_MISMATCH),
                     errmsg("collations are not supported by type %s",
                            format_type_be(HeapTupleGetOid(ctype))),
                     parser_errposition(cxt->pstate,
                                        column->collClause->location)));
    }

    ReleaseSysCache(ctype);
}


/*
 * transformCreateSchemaStmt -
 *    analyzes the CREATE SCHEMA statement
 *
 * Split the schema element list into individual commands and place
 * them in the result list in an order such that there are no forward
 * references (e.g. GRANT to a table created later in the list). Note
 * that the logic we use for determining forward references is
 * presently quite incomplete.
 *
 * SQL92 also allows constraints to make forward references, so thumb through
 * the table columns and move forward references to a posterior alter-table
 * command.
 *
 * The result is a list of parse nodes that still need to be analyzed ---
 * but we can't analyze the later commands until we've executed the earlier
 * ones, because of possible inter-object references.
 *
 * Note: this breaks the rules a little bit by modifying schema-name fields
 * within passed-in structs.  However, the transformation would be the same
 * if done over, so it should be all right to scribble on the input to this
 * extent.
 */
List *
transformCreateSchemaStmt(CreateSchemaStmt *stmt)
{
    CreateSchemaStmtContext cxt;
    List       *result;
    ListCell   *elements;

    cxt.stmtType = "CREATE SCHEMA";
    cxt.schemaname = stmt->schemaname;
    cxt.authid = stmt->authid;
    cxt.sequences = NIL;
    cxt.tables = NIL;
    cxt.views = NIL;
    cxt.indexes = NIL;
    cxt.triggers = NIL;
    cxt.grants = NIL;

    /*
     * Run through each schema element in the schema element list. Separate
     * statements by type, and do preliminary analysis.
     */
    foreach(elements, stmt->schemaElts)
    {
        Node       *element = lfirst(elements);

        switch (nodeTag(element))
        {
            case T_CreateSeqStmt:
                {
                    CreateSeqStmt *elp = (CreateSeqStmt *) element;

                    setSchemaName(cxt.schemaname, &elp->sequence->schemaname);
                    cxt.sequences = lappend(cxt.sequences, element);
                }
                break;

            case T_CreateStmt:
                {
                    CreateStmt *elp = (CreateStmt *) element;

                    setSchemaName(cxt.schemaname, &elp->relation->schemaname);

                    /*
                     * XXX todo: deal with constraints
                     */
                    cxt.tables = lappend(cxt.tables, element);
                }
                break;

            case T_ViewStmt:
                {
                    ViewStmt   *elp = (ViewStmt *) element;

                    setSchemaName(cxt.schemaname, &elp->view->schemaname);

                    /*
                     * XXX todo: deal with references between views
                     */
                    cxt.views = lappend(cxt.views, element);
                }
                break;

            case T_IndexStmt:
                {
                    IndexStmt  *elp = (IndexStmt *) element;

                    setSchemaName(cxt.schemaname, &elp->relation->schemaname);
                    cxt.indexes = lappend(cxt.indexes, element);
                }
                break;

            case T_CreateTrigStmt:
                {
                    CreateTrigStmt *elp = (CreateTrigStmt *) element;

                    setSchemaName(cxt.schemaname, &elp->relation->schemaname);
                    cxt.triggers = lappend(cxt.triggers, element);
                }
                break;

            case T_GrantStmt:
                cxt.grants = lappend(cxt.grants, element);
                break;

            default:
                elog(ERROR, "unrecognized node type: %d",
                     (int) nodeTag(element));
        }
    }

    result = NIL;
    result = list_concat(result, cxt.sequences);
    result = list_concat(result, cxt.tables);
    result = list_concat(result, cxt.views);
    result = list_concat(result, cxt.indexes);
    result = list_concat(result, cxt.triggers);
    result = list_concat(result, cxt.grants);

    return result;
}

/*
 * setSchemaName
 *      Set or check schema name in an element of a CREATE SCHEMA command
 */
static void
setSchemaName(char *context_schema, char **stmt_schema_name)
{
    if (*stmt_schema_name == NULL)
        *stmt_schema_name = context_schema;
    else if (strcmp(context_schema, *stmt_schema_name) != 0)
        ereport(ERROR,
                (errcode(ERRCODE_INVALID_SCHEMA_DEFINITION),
                 errmsg("CREATE specifies a schema (%s) "
                        "different from the one being created (%s)",
                        *stmt_schema_name, context_schema)));
}