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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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43
src/backend/access/heap/tuptoaster.c
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@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/access/heap/tuptoaster.c,v 1.85 2008/03/26 21:10:37 alvherre Exp $
* $PostgreSQL: pgsql/src/backend/access/heap/tuptoaster.c,v 1.86 2008/04/12 23:14:21 tgl Exp $
*
*
* INTERFACE ROUTINES
@ -1184,7 +1184,9 @@ toast_save_datum(Relation rel, Datum value,
toast_pointer.va_extsize = data_todo;
}
toast_pointer.va_valueid = GetNewOidWithIndex(toastrel, toastidx);
toast_pointer.va_valueid = GetNewOidWithIndex(toastrel,
RelationGetRelid(toastidx),
(AttrNumber) 1);
toast_pointer.va_toastrelid = rel->rd_rel->reltoastrelid;
/*
@ -1273,7 +1275,7 @@ toast_delete_datum(Relation rel, Datum value)
Relation toastrel;
Relation toastidx;
ScanKeyData toastkey;
IndexScanDesc toastscan;
SysScanDesc toastscan;
HeapTuple toasttup;
if (!VARATT_IS_EXTERNAL(attr))
@ -1289,8 +1291,7 @@ toast_delete_datum(Relation rel, Datum value)
toastidx = index_open(toastrel->rd_rel->reltoastidxid, RowExclusiveLock);
/*
* Setup a scan key to fetch from the index by va_valueid (we don't
* particularly care whether we see them in sequence or not)
* Setup a scan key to find chunks with matching va_valueid
*/
ScanKeyInit(&toastkey,
(AttrNumber) 1,
@ -1298,11 +1299,13 @@ toast_delete_datum(Relation rel, Datum value)
ObjectIdGetDatum(toast_pointer.va_valueid));
/*
* Find the chunks by index
* Find all the chunks. (We don't actually care whether we see them in
* sequence or not, but since we've already locked the index we might
* as well use systable_beginscan_ordered.)
*/
toastscan = index_beginscan(toastrel, toastidx,
SnapshotToast, 1, &toastkey);
while ((toasttup = index_getnext(toastscan, ForwardScanDirection)) != NULL)
toastscan = systable_beginscan_ordered(toastrel, toastidx,
SnapshotToast, 1, &toastkey);
while ((toasttup = systable_getnext_ordered(toastscan, ForwardScanDirection)) != NULL)
{
/*
* Have a chunk, delete it
@ -1313,7 +1316,7 @@ toast_delete_datum(Relation rel, Datum value)
/*
* End scan and close relations
*/
index_endscan(toastscan);
systable_endscan_ordered(toastscan);
index_close(toastidx, RowExclusiveLock);
heap_close(toastrel, RowExclusiveLock);
}
@ -1332,7 +1335,7 @@ toast_fetch_datum(struct varlena * attr)
Relation toastrel;
Relation toastidx;
ScanKeyData toastkey;
IndexScanDesc toastscan;
SysScanDesc toastscan;
HeapTuple ttup;
TupleDesc toasttupDesc;
struct varlena *result;
@ -1383,9 +1386,9 @@ toast_fetch_datum(struct varlena * attr)
*/
nextidx = 0;
toastscan = index_beginscan(toastrel, toastidx,
SnapshotToast, 1, &toastkey);
while ((ttup = index_getnext(toastscan, ForwardScanDirection)) != NULL)
toastscan = systable_beginscan_ordered(toastrel, toastidx,
SnapshotToast, 1, &toastkey);
while ((ttup = systable_getnext_ordered(toastscan, ForwardScanDirection)) != NULL)
{
/*
* Have a chunk, extract the sequence number and the data
@ -1464,7 +1467,7 @@ toast_fetch_datum(struct varlena * attr)
/*
* End scan and close relations
*/
index_endscan(toastscan);
systable_endscan_ordered(toastscan);
index_close(toastidx, AccessShareLock);
heap_close(toastrel, AccessShareLock);
@ -1485,7 +1488,7 @@ toast_fetch_datum_slice(struct varlena * attr, int32 sliceoffset, int32 length)
Relation toastidx;
ScanKeyData toastkey[3];
int nscankeys;
IndexScanDesc toastscan;
SysScanDesc toastscan;
HeapTuple ttup;
TupleDesc toasttupDesc;
struct varlena *result;
@ -1592,9 +1595,9 @@ toast_fetch_datum_slice(struct varlena * attr, int32 sliceoffset, int32 length)
* The index is on (valueid, chunkidx) so they will come in order
*/
nextidx = startchunk;
toastscan = index_beginscan(toastrel, toastidx,
SnapshotToast, nscankeys, toastkey);
while ((ttup = index_getnext(toastscan, ForwardScanDirection)) != NULL)
toastscan = systable_beginscan_ordered(toastrel, toastidx,
SnapshotToast, nscankeys, toastkey);
while ((ttup = systable_getnext_ordered(toastscan, ForwardScanDirection)) != NULL)
{
/*
* Have a chunk, extract the sequence number and the data
@ -1681,7 +1684,7 @@ toast_fetch_datum_slice(struct varlena * attr, int32 sliceoffset, int32 length)
/*
* End scan and close relations
*/
index_endscan(toastscan);
systable_endscan_ordered(toastscan);
index_close(toastidx, AccessShareLock);
heap_close(toastrel, AccessShareLock);