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Restructure index access method API to hide most of it at the C level.

This patch reduces pg_am to just two columns, a name and a handler
function.  All the data formerly obtained from pg_am is now provided
in a C struct returned by the handler function.  This is similar to
the designs we've adopted for FDWs and tablesample methods.  There
are multiple advantages.  For one, the index AM's support functions
are now simple C functions, making them faster to call and much less
error-prone, since the C compiler can now check function signatures.
For another, this will make it far more practical to define index access
methods in installable extensions.

A disadvantage is that SQL-level code can no longer see attributes
of index AMs; in particular, some of the crosschecks in the opr_sanity
regression test are no longer possible from SQL.  We've addressed that
by adding a facility for the index AM to perform such checks instead.
(Much more could be done in that line, but for now we're content if the
amvalidate functions more or less replace what opr_sanity used to do.)
We might also want to expose some sort of reporting functionality, but
this patch doesn't do that.

Alexander Korotkov, reviewed by Petr Jelínek, and rather heavily
editorialized on by me.
This commit is contained in:
Tom Lane
2016-01-17 19:36:59 -05:00
parent 8d290c8ec6
commit 65c5fcd353
93 changed files with 2493 additions and 1924 deletions

View File

@ -14,7 +14,7 @@
#ifndef NBTREE_H
#define NBTREE_H
#include "access/genam.h"
#include "access/amapi.h"
#include "access/itup.h"
#include "access/sdir.h"
#include "access/xlogreader.h"
@ -654,20 +654,28 @@ typedef BTScanOpaqueData *BTScanOpaque;
/*
* prototypes for functions in nbtree.c (external entry points for btree)
*/
extern Datum btbuild(PG_FUNCTION_ARGS);
extern Datum btbuildempty(PG_FUNCTION_ARGS);
extern Datum btinsert(PG_FUNCTION_ARGS);
extern Datum btbeginscan(PG_FUNCTION_ARGS);
extern Datum btgettuple(PG_FUNCTION_ARGS);
extern Datum btgetbitmap(PG_FUNCTION_ARGS);
extern Datum btrescan(PG_FUNCTION_ARGS);
extern Datum btendscan(PG_FUNCTION_ARGS);
extern Datum btmarkpos(PG_FUNCTION_ARGS);
extern Datum btrestrpos(PG_FUNCTION_ARGS);
extern Datum btbulkdelete(PG_FUNCTION_ARGS);
extern Datum btvacuumcleanup(PG_FUNCTION_ARGS);
extern Datum btcanreturn(PG_FUNCTION_ARGS);
extern Datum btoptions(PG_FUNCTION_ARGS);
extern Datum bthandler(PG_FUNCTION_ARGS);
extern IndexBuildResult *btbuild(Relation heap, Relation index,
struct IndexInfo *indexInfo);
extern void btbuildempty(Relation index);
extern bool btinsert(Relation rel, Datum *values, bool *isnull,
ItemPointer ht_ctid, Relation heapRel,
IndexUniqueCheck checkUnique);
extern IndexScanDesc btbeginscan(Relation rel, int nkeys, int norderbys);
extern bool btgettuple(IndexScanDesc scan, ScanDirection dir);
extern int64 btgetbitmap(IndexScanDesc scan, TIDBitmap *tbm);
extern void btrescan(IndexScanDesc scan, ScanKey scankey, int nscankeys,
ScanKey orderbys, int norderbys);
extern void btendscan(IndexScanDesc scan);
extern void btmarkpos(IndexScanDesc scan);
extern void btrestrpos(IndexScanDesc scan);
extern IndexBulkDeleteResult *btbulkdelete(IndexVacuumInfo *info,
IndexBulkDeleteResult *stats,
IndexBulkDeleteCallback callback,
void *callback_state);
extern IndexBulkDeleteResult *btvacuumcleanup(IndexVacuumInfo *info,
IndexBulkDeleteResult *stats);
extern bool btcanreturn(Relation index, int attno);
/*
* prototypes for functions in nbtinsert.c
@ -738,6 +746,12 @@ extern void _bt_end_vacuum(Relation rel);
extern void _bt_end_vacuum_callback(int code, Datum arg);
extern Size BTreeShmemSize(void);
extern void BTreeShmemInit(void);
extern bytea *btoptions(Datum reloptions, bool validate);
/*
* prototypes for functions in nbtvalidate.c
*/
extern bool btvalidate(Oid opclassoid);
/*
* prototypes for functions in nbtsort.c