postgresql/src/include/commands/sequence.h

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/*-------------------------------------------------------------------------
*
* sequence.h
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* prototypes for sequence.c.
*
* Portions Copyright (c) 1996-2021, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
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* src/include/commands/sequence.h
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*
*-------------------------------------------------------------------------
*/
#ifndef SEQUENCE_H
#define SEQUENCE_H
Revamp the WAL record format. Each WAL record now carries information about the modified relation and block(s) in a standardized format. That makes it easier to write tools that need that information, like pg_rewind, prefetching the blocks to speed up recovery, etc. There's a whole new API for building WAL records, replacing the XLogRecData chains used previously. The new API consists of XLogRegister* functions, which are called for each buffer and chunk of data that is added to the record. The new API also gives more control over when a full-page image is written, by passing flags to the XLogRegisterBuffer function. This also simplifies the XLogReadBufferForRedo() calls. The function can dig the relation and block number from the WAL record, so they no longer need to be passed as arguments. For the convenience of redo routines, XLogReader now disects each WAL record after reading it, copying the main data part and the per-block data into MAXALIGNed buffers. The data chunks are not aligned within the WAL record, but the redo routines can assume that the pointers returned by XLogRecGet* functions are. Redo routines are now passed the XLogReaderState, which contains the record in the already-disected format, instead of the plain XLogRecord. The new record format also makes the fixed size XLogRecord header smaller, by removing the xl_len field. The length of the "main data" portion is now stored at the end of the WAL record, and there's a separate header after XLogRecord for it. The alignment padding at the end of XLogRecord is also removed. This compansates for the fact that the new format would otherwise be more bulky than the old format. Reviewed by Andres Freund, Amit Kapila, Michael Paquier, Alvaro Herrera, Fujii Masao.
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#include "access/xlogreader.h"
#include "catalog/objectaddress.h"
#include "fmgr.h"
#include "lib/stringinfo.h"
#include "nodes/parsenodes.h"
#include "parser/parse_node.h"
#include "storage/relfilenode.h"
typedef struct FormData_pg_sequence_data
{
int64 last_value;
int64 log_cnt;
bool is_called;
} FormData_pg_sequence_data;
typedef FormData_pg_sequence_data *Form_pg_sequence_data;
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/*
* Columns of a sequence relation
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*/
#define SEQ_COL_LASTVAL 1
#define SEQ_COL_LOG 2
#define SEQ_COL_CALLED 3
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#define SEQ_COL_FIRSTCOL SEQ_COL_LASTVAL
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#define SEQ_COL_LASTCOL SEQ_COL_CALLED
/* XLOG stuff */
#define XLOG_SEQ_LOG 0x00
typedef struct xl_seq_rec
{
RelFileNode node;
/* SEQUENCE TUPLE DATA FOLLOWS AT THE END */
} xl_seq_rec;
extern int64 nextval_internal(Oid relid, bool check_permissions);
extern Datum nextval(PG_FUNCTION_ARGS);
extern List *sequence_options(Oid relid);
extern ObjectAddress DefineSequence(ParseState *pstate, CreateSeqStmt *stmt);
extern ObjectAddress AlterSequence(ParseState *pstate, AlterSeqStmt *stmt);
extern void DeleteSequenceTuple(Oid relid);
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extern void ResetSequence(Oid seq_relid);
extern void ResetSequenceCaches(void);
Revamp the WAL record format. Each WAL record now carries information about the modified relation and block(s) in a standardized format. That makes it easier to write tools that need that information, like pg_rewind, prefetching the blocks to speed up recovery, etc. There's a whole new API for building WAL records, replacing the XLogRecData chains used previously. The new API consists of XLogRegister* functions, which are called for each buffer and chunk of data that is added to the record. The new API also gives more control over when a full-page image is written, by passing flags to the XLogRegisterBuffer function. This also simplifies the XLogReadBufferForRedo() calls. The function can dig the relation and block number from the WAL record, so they no longer need to be passed as arguments. For the convenience of redo routines, XLogReader now disects each WAL record after reading it, copying the main data part and the per-block data into MAXALIGNed buffers. The data chunks are not aligned within the WAL record, but the redo routines can assume that the pointers returned by XLogRecGet* functions are. Redo routines are now passed the XLogReaderState, which contains the record in the already-disected format, instead of the plain XLogRecord. The new record format also makes the fixed size XLogRecord header smaller, by removing the xl_len field. The length of the "main data" portion is now stored at the end of the WAL record, and there's a separate header after XLogRecord for it. The alignment padding at the end of XLogRecord is also removed. This compansates for the fact that the new format would otherwise be more bulky than the old format. Reviewed by Andres Freund, Amit Kapila, Michael Paquier, Alvaro Herrera, Fujii Masao.
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extern void seq_redo(XLogReaderState *rptr);
extern void seq_desc(StringInfo buf, XLogReaderState *rptr);
extern const char *seq_identify(uint8 info);
extern void seq_mask(char *pagedata, BlockNumber blkno);
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#endif /* SEQUENCE_H */