Inno Db Internals Inno Db File Formats And Source Code Structure

Transactional Storage for MySQL FAST. RELIABLE. PROVEN. InnoDB Internals: InnoDB File Formats and Source Code Structure MySQL Conference, April 2009 Heikki Tuuri Calvin Sun CEO Innobase Oy Principal Engineer Vice President, Development Oracle Corporation Oracle Corporation

Today’s Topics • Goals of InnoDB • Key Functional Characteristics • InnoDB Design Considerations • InnoDB Architecture • InnoDB On Disk Format • Source Code Structure • Q&A

Goals of InnoDB • OLTP oriented • Performance, Reliability, Scalability • Data Protection • Portability

InnoDB Key Functional Characteristics • Full transaction support • Row-level locking • MVCC • Crash recovery • Efficient IO

Design Considerations • Modeled on Gray & Reuter’s “Transactions Processing: Concepts & Techniques” • Also emulated the Oracle architecture • Added unique subsystems • Doublewrite • Insert buffering • Adaptive hash index • Designed to evolve with changing hardware & requirements

InnoDB Architecture Server Applications Handler API Embedded InnoDB API Transaction Cursor / Row Mini- B-tree Lock transaction Page Buffer File Space Manager IO

InnoDB On Disk Format • InnoDB Database Files • InnoDB Tablespaces • InnoDB Pages / Extents • InnoDB Rows • InnoDB Indexes • InnoDB Logs • File Format Design Considerations

InnoDB Database Files MySQL Data Directory System tablespace InnoDB tables internal data .frm files dictionary innodb_file_per_table OR insert buffer undo logs .ibd files ibdata files

InnoDB Tablespaces • A tablespace consists of multiple files and/or raw disk partitions. file_name:file_size[:autoextend[:max:max_file_size]] • A file/partition is a collection of segments. • A segment consists of fixed-length pages. • The page size is always 16KB in uncompressed tablespaces, and 1KB-16KB in compressed tablespaces (for both data and index).

System Tablespace • Internal Data Dictionary • Undo • Insert Buffer • Doublewrite Buffer • MySQL Replication Info

InnoDB Tablespaces Tablespace Segment Extent Extent Leaf node segment Non-leaf node segment Extent Extent Extent Rollback segment Page Row Row Row Trx id Row Row Row Roll pointer Row Row Field pointers Field 1 Field 2 Field n an extent = 64 pages

InnoDB Pages InnoDB Page Types Symbol Value Notes 3 File segment inode FIL_PAGE_INODE 17855 B-tree node FIL_PAGE_INDEX 10 Uncompressed BLOB page FIL_PAGE_TYPE_BLOB 1st compressed BLOB page 11 FIL_PAGE_TYPE_ZBLOB 12 Subsequent compressed BLOB page FIL_PAGE_TYPE_ZBLOB2 6 System page FIL_PAGE_TYPE_SYS 7 Transaction system page FIL_PAGE_TYPE_TRX_SYS i-buf bitmap, I-buf free list, file space others header, extent desp page, new allocated page

InnoDB Pages A page consists of: a page header, a page trailer, and a page body (rows or other contents). Page header Row Row Row Row Row Row Row Row Row Row Row row offset array Page trailer

Page Declares typedef struct /* a space address */ { ulint pageno; /* page number within the file */ ulint boffset; /* byte offset within the page */ } fil_addr_t; typedef struct { ulint checksum; /* checksum of the page (since 4.0.14) */ ulint page_offset; /* page offset inside space */ fil_addr_t previous; /* offset or fil_addr_t */ fil_addr_t next; /* offset or fil_addr_t */ dulint page_lsn; /* lsn of the end of the newest modification log record to the page */ PAGE_TYPE page type; /* file page type */ dulint file_flush_lsn;/* the file has been flushed to disk at least up to this lsn */ int space_id; /* space id of the page */ char data[]; /* will grow */ ulint page_lsn; /* the last 4 bytes of page_lsn */ ulint checksum; /* page checksum, or checksum magic, or 0 */ } PAGE, *PAGE;

InnoDB Compressed Pages • InnoDB keeps a “modification Page header log” in each page • Updates & inserts of small compressed data records are written to the log w/o page reconstruction; deletes don’t even require uncompression • Log also tells InnoDB if the modification log page will compress to fit page empty space size BLOB pointers • When log space runs out, InnoDB uncompresses the page directory page, applies the changes and Page trailer recompresses the page

InnoDB Rows … … prefix(768B) COMACT format overflow 20 bytes page … … DYNAMIC format overflow page Record hdr Trx ID Roll ptr Fld ptrs overflow-page ptr .. Field values

InnoDB Indexes - Primary rows are stored ●Data PK values 001 - nnn … … in the B-tree leaf nodes of a clustered index 001 – 500 – 801 – 500 800 nnn ●B-tree is organized xxx by primary key or - 501 631 769 801 950 001 276 – nnn - - - - - - 500 630 768 800 949 xxx 275 non-null unique key of table, if defined; clustered else, an internal (primary key) index Key values column with 6-byte 501- 501-630 Primary Index + data for corresponding rows ROW_ID is added.

InnoDB Indexes - Secondary clustered clustered (primary key) (primary PK values key) index - nnn 001 index ● Secondary index B- tree leaf nodes contain, for each key value, the primary B-tree leaf nodes, containing data keys of the corresponding rows, used to access key values AZ clustering index to obtain the data Secondary Index B-tree leaf nodes, containing PKs Secondary index Secondary index

InnoDB Logging Rollback segments Log Buffer Buffer Pool log thread write thread Log File Log File redo DATA #1 rollback #2 log log files ibdata files

InnoDB Redo Log end of log start of log last checkpoint min LSN Redo log structure: Space id PageNo OpCode Data

File Format Management • Builtin InnoDB format: “Antelope” • New “Barracuda” format enables compression,ROW_FORMAT=DYNAMIC • Fast index creation, other features do not .ibd require Barracuda file format data files (file per • Builtin InnoDB can access “Antelope” table) databases, but not “Barracuda” databases • Check file format tag in system tablespace on startup • Enable a file format with new dynamic parameter innodb_file_format • Preserves ability to downgrade easily

InnoDB File Format Design Considerations • Durability • Logging, doublewrite, checksum; • Performance • Insert buffering, table compression • Efficiency • Dynamic row format, table compression • Compatibility • File format management

Source Code Structure • 31 subdirectories • Relevant InnoDB source files on file formats • Tablespace: fsp0fsp {.c, .ic, .h} • Page: page0page, page0zip {.c, .ic, .h} • Log: log0log {.c, .ic, .h}

Source Code Subdirectories • buf • ibuf • que • data • include • read • db • lock • rem • dict • log • row • dyn • math • srv • eval • mem • sync • fil • mtr • thr • fsp • os • trx • fut • page • usr • ha • pars • ut • handler

Summary: Durability, Performance, Compatibility & Efficiency • InnoDB is the leading transactional storage engine for MySQL • InnoDB’s architecture is well-suited to modern, on- line transactional applications; as well as embedded applications. • InnoDB’s file format is designed for high durability, better performance, and easy to manage

For More Information … 2009 MySQL User Conference InnoDB Birds of a Feather Wed 7:30pm Ballroom C • Heikki Tuuri: Concurrency Control: How it Really Works, Thurs, 2:50pm Please visit www.innodb.com, blogs.innodb.com and forums.innodb.com

QUESTIONS ANSWERS

an company Plugin Hot Backup Embedded

InnoDB Size Limits Max # of tables: 4 G • Max size of a table: 32TB • Columns per table: 1000 • Max row size: n*4 GB • • 8 kB if stored on the same page • n*4 GB with n BLOBs • Max key length: 3500 • Maximum tablespace size: 64 TB • Max # of concurrent trxs: 1023

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Inno Db Internals Inno Db File Formats And Source Code Structure

by MySQLConference

on May 11, 2009

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Inno Db Internals Inno Db File Formats And Source Code Structure Presentation Transcript