postgres_fdw.h

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/*-------------------------------------------------------------------------
 *
 * postgres_fdw.h
 *        Foreign-data wrapper for remote PostgreSQL servers
 *
 * Portions Copyright (c) 2012-2016, PostgreSQL Global Development Group
 *
 * IDENTIFICATION
 *        contrib/postgres_fdw/postgres_fdw.h
 *
 *-------------------------------------------------------------------------
 */
#ifndef POSTGRES_FDW_H
#define POSTGRES_FDW_H

#include "foreign/foreign.h"
#include "lib/stringinfo.h"
#include "nodes/relation.h"
#include "utils/relcache.h"

#include "libpq-fe.h"

/*
 * FDW-specific planner information kept in RelOptInfo.fdw_private for a
 * foreign table.  This information is collected by postgresGetForeignRelSize.
 */
typedef struct PgFdwRelationInfo
{
    /*
     * True means that the relation can be pushed down. Always true for simple
     * foreign scan.
     */
    bool        pushdown_safe;

    /*
     * Restriction clauses, divided into safe and unsafe to pushdown subsets.
     *
     * For a base foreign relation this is a list of clauses along-with
     * RestrictInfo wrapper. Keeping RestrictInfo wrapper helps while dividing
     * scan_clauses in postgresGetForeignPlan into safe and unsafe subsets.
     * Also it helps in estimating costs since RestrictInfo caches the
     * selectivity and qual cost for the clause in it.
     *
     * For a join relation, however, they are part of otherclause list
     * obtained from extract_actual_join_clauses, which strips RestrictInfo
     * construct. So, for a join relation they are list of bare clauses.
     */
    List       *remote_conds;
    List       *local_conds;

    /* Bitmap of attr numbers we need to fetch from the remote server. */
    Bitmapset  *attrs_used;

    /* Cost and selectivity of local_conds. */
    QualCost    local_conds_cost;
    Selectivity local_conds_sel;

    /* Selectivity of join conditions */
    Selectivity joinclause_sel;

    /* Estimated size and cost for a scan or join. */
    double      rows;
    int         width;
    Cost        startup_cost;
    Cost        total_cost;
    /* Costs excluding costs for transferring data from the foreign server */
    Cost        rel_startup_cost;
    Cost        rel_total_cost;

    /* Options extracted from catalogs. */
    bool        use_remote_estimate;
    Cost        fdw_startup_cost;
    Cost        fdw_tuple_cost;
    List       *shippable_extensions;   /* OIDs of whitelisted extensions */

    /* Cached catalog information. */
    ForeignTable *table;
    ForeignServer *server;
    UserMapping *user;          /* only set in use_remote_estimate mode */

    int         fetch_size;      /* fetch size for this remote table */

    /*
     * Name of the relation while EXPLAINing ForeignScan. It is used for join
     * relations but is set for all relations. For join relation, the name
     * indicates which foreign tables are being joined and the join type used.
     */
    StringInfo  relation_name;

    /* Join information */
    RelOptInfo *outerrel;
    RelOptInfo *innerrel;
    JoinType    jointype;
    List       *joinclauses;
} PgFdwRelationInfo;

/* in postgres_fdw.c */
extern int  set_transmission_modes(void);
extern void reset_transmission_modes(int nestlevel);

/* in connection.c */
extern PGconn *GetConnection(UserMapping *user, bool will_prep_stmt);
extern void ReleaseConnection(PGconn *conn);
extern unsigned int GetCursorNumber(PGconn *conn);
extern unsigned int GetPrepStmtNumber(PGconn *conn);
extern PGresult *pgfdw_get_result(PGconn *conn, const char *query);
extern PGresult *pgfdw_exec_query(PGconn *conn, const char *query);
extern void pgfdw_report_error(int elevel, PGresult *res, PGconn *conn,
                   bool clear, const char *sql);

/* in option.c */
extern int ExtractConnectionOptions(List *defelems,
                         const char **keywords,
                         const char **values);
extern List *ExtractExtensionList(const char *extensionsString,
                     bool warnOnMissing);

/* in deparse.c */
extern void classifyConditions(PlannerInfo *root,
                   RelOptInfo *baserel,
                   List *input_conds,
                   List **remote_conds,
                   List **local_conds);
extern bool is_foreign_expr(PlannerInfo *root,
                RelOptInfo *baserel,
                Expr *expr);
extern void deparseInsertSql(StringInfo buf, PlannerInfo *root,
                 Index rtindex, Relation rel,
                 List *targetAttrs, bool doNothing, List *returningList,
                 List **retrieved_attrs);
extern void deparseUpdateSql(StringInfo buf, PlannerInfo *root,
                 Index rtindex, Relation rel,
                 List *targetAttrs, List *returningList,
                 List **retrieved_attrs);
extern void deparseDirectUpdateSql(StringInfo buf, PlannerInfo *root,
                                   Index rtindex, Relation rel,
                                   List *targetlist,
                                   List *targetAttrs,
                                   List *remote_conds,
                                   List **params_list,
                                   List *returningList,
                                   List **retrieved_attrs);
extern void deparseDeleteSql(StringInfo buf, PlannerInfo *root,
                 Index rtindex, Relation rel,
                 List *returningList,
                 List **retrieved_attrs);
extern void deparseDirectDeleteSql(StringInfo buf, PlannerInfo *root,
                                   Index rtindex, Relation rel,
                                   List *remote_conds,
                                   List **params_list,
                                   List *returningList,
                                   List **retrieved_attrs);
extern void deparseAnalyzeSizeSql(StringInfo buf, Relation rel);
extern void deparseAnalyzeSql(StringInfo buf, Relation rel,
                  List **retrieved_attrs);
extern void deparseStringLiteral(StringInfo buf, const char *val);
extern Expr *find_em_expr_for_rel(EquivalenceClass *ec, RelOptInfo *rel);
extern List *build_tlist_to_deparse(RelOptInfo *foreign_rel);
extern void deparseSelectStmtForRel(StringInfo buf, PlannerInfo *root,
                        RelOptInfo *foreignrel, List *tlist,
                        List *remote_conds, List *pathkeys,
                        List **retrieved_attrs, List **params_list);

/* in shippable.c */
extern bool is_builtin(Oid objectId);
extern bool is_shippable(Oid objectId, Oid classId, PgFdwRelationInfo *fpinfo);
extern const char *get_jointype_name(JoinType jointype);

#endif   /* POSTGRES_FDW_H */