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Create new routines systable_beginscan_ordered, systable_getnext_ordered,

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systable_endscan_ordered that have API similar to systable_beginscan etc
(in particular, the passed-in scankeys have heap not index attnums),
but guarantee ordered output, unlike the existing functions.  For the moment
these are just very thin wrappers around index_beginscan/index_getnext/etc.
Someday they might need to get smarter; but for now this is just a code
refactoring exercise to reduce the number of direct callers of index_getnext,
in preparation for changing that function's API.

In passing, remove index_getnext_indexitem, which has been dead code for
quite some time, and will have even less use than that in the presence
of run-time-lossy indexes.
This commit is contained in:
Tom Lane
2008-04-12 23:14:21 +00:00
parent 00832809a0
commit ec498cdcbb
9 changed files with 168 additions and 124 deletions
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11
src/include/access/genam.h
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@@ -7,7 +7,7 @@
* Portions Copyright (c) 1996-2008, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
* $PostgreSQL: pgsql/src/include/access/genam.h,v 1.70 2008/04/10 22:25:25 tgl Exp $
* $PostgreSQL: pgsql/src/include/access/genam.h,v 1.71 2008/04/12 23:14:21 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@@ -108,8 +108,6 @@ extern void index_endscan(IndexScanDesc scan);
extern void index_markpos(IndexScanDesc scan);
extern void index_restrpos(IndexScanDesc scan);
extern HeapTuple index_getnext(IndexScanDesc scan, ScanDirection direction);
extern bool index_getnext_indexitem(IndexScanDesc scan,
ScanDirection direction);
extern int64 index_getbitmap(IndexScanDesc scan, TIDBitmap *bitmap);
extern IndexBulkDeleteResult *index_bulk_delete(IndexVacuumInfo *info,
@@ -140,5 +138,12 @@ extern SysScanDesc systable_beginscan(Relation heapRelation,
int nkeys, ScanKey key);
extern HeapTuple systable_getnext(SysScanDesc sysscan);
extern void systable_endscan(SysScanDesc sysscan);
extern SysScanDesc systable_beginscan_ordered(Relation heapRelation,
Relation indexRelation,
Snapshot snapshot,
int nkeys, ScanKey key);
extern HeapTuple systable_getnext_ordered(SysScanDesc sysscan,
ScanDirection direction);
extern void systable_endscan_ordered(SysScanDesc sysscan);
#endif /* GENAM_H */

10
src/include/access/relscan.h
View File

@@ -7,7 +7,7 @@
* Portions Copyright (c) 1996-2008, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
* $PostgreSQL: pgsql/src/include/access/relscan.h,v 1.62 2008/04/10 22:25:25 tgl Exp $
* $PostgreSQL: pgsql/src/include/access/relscan.h,v 1.63 2008/04/12 23:14:21 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@@ -76,14 +76,12 @@ typedef struct IndexScanDescData
/* index access method's private state */
void *opaque; /* access-method-specific info */
/*
* xs_ctup/xs_cbuf are valid after a successful index_getnext. After
* index_getnext_indexitem, xs_ctup.t_self contains the heap tuple TID
* from the index entry, but its other fields are not valid.
*/
/* xs_ctup/xs_cbuf are valid after a successful index_getnext */
HeapTupleData xs_ctup; /* current heap tuple, if any */
Buffer xs_cbuf; /* current heap buffer in scan, if any */
/* NB: if xs_cbuf is not InvalidBuffer, we hold a pin on that buffer */
/* state data for traversing HOT chains in index_getnext */
TransactionId xs_prev_xmax; /* previous HOT chain member's XMAX, if any */
OffsetNumber xs_next_hot; /* next member of HOT chain, if any */
bool xs_hot_dead; /* T if all members of HOT chain are dead */