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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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48
src/backend/access/index/indexam.c
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@@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/access/index/indexam.c,v 1.105 2008/04/10 22:25:25 tgl Exp $
* $PostgreSQL: pgsql/src/backend/access/index/indexam.c,v 1.106 2008/04/12 23:14:21 tgl Exp $
*
* INTERFACE ROUTINES
* index_open - open an index relation by relation OID
@@ -206,12 +206,7 @@ index_insert(Relation indexRelation,
/*
* index_beginscan - start a scan of an index with amgettuple
*
* Note: heapRelation may be NULL if there is no intention of calling
* index_getnext on this scan; index_getnext_indexitem will not use the
* heapRelation link (nor the snapshot). However, the caller had better
* be holding some kind of lock on the heap relation in any case, to ensure
* no one deletes it (or the index) out from under us. Caller must also
* be holding a lock on the index.
* Caller must be holding suitable locks on the heap and the index.
*/
IndexScanDesc
index_beginscan(Relation heapRelation,
@@ -634,45 +629,6 @@ index_getnext(IndexScanDesc scan, ScanDirection direction)
return NULL; /* failure exit */
}
/* ----------------
* index_getnext_indexitem - get the next index tuple from a scan
*
* Finds the next index tuple satisfying the scan keys. Note that the
* corresponding heap tuple is not accessed, and thus no time qual (snapshot)
* check is done, other than the index AM's internal check for killed tuples
* (which most callers of this routine will probably want to suppress by
* setting scan->ignore_killed_tuples = false).
*
* On success (TRUE return), the heap TID of the found index entry is in
* scan->xs_ctup.t_self. scan->xs_cbuf is untouched.
* ----------------
*/
bool
index_getnext_indexitem(IndexScanDesc scan,
ScanDirection direction)
{
FmgrInfo *procedure;
bool found;
SCAN_CHECKS;
GET_SCAN_PROCEDURE(amgettuple);
/* just make sure this is false... */
scan->kill_prior_tuple = false;
/*
* have the am's gettuple proc do all the work.
*/
found = DatumGetBool(FunctionCall2(procedure,
PointerGetDatum(scan),
Int32GetDatum(direction)));
if (found)
pgstat_count_index_tuples(scan->indexRelation, 1);
return found;
}
/* ----------------
* index_getbitmap - get all tuples at once from an index scan
*