database/postgres
1
0
Fork 0
mirror of https://github.com/postgres/postgres.git synced 2025-07-11 10:01:57 +03:00
Code Activity

Support index-only scans using the visibility map to avoid heap fetches.

Browse Source 
When a btree index contains all columns required by the query, and the
visibility map shows that all tuples on a target heap page are
visible-to-all, we don't need to fetch that heap page.  This patch depends
on the previous patches that made the visibility map reliable.

There's a fair amount left to do here, notably trying to figure out a less
chintzy way of estimating the cost of an index-only scan, but the core
functionality seems ready to commit.

Robert Haas and Ibrar Ahmed, with some previous work by Heikki Linnakangas.
This commit is contained in:
Tom Lane
2011-10-07 20:13:02 -04:00
parent caa1054df8
commit a2822fb933
34 changed files with 704 additions and 203 deletions
Download Patch File Download Diff File Expand all files Collapse all files

9
src/backend/optimizer/plan/createplan.c
View File

@ -95,7 +95,7 @@ static SeqScan *make_seqscan(List *qptlist, List *qpqual, Index scanrelid);
static IndexScan *make_indexscan(List *qptlist, List *qpqual, Index scanrelid,
Oid indexid, List *indexqual, List *indexqualorig,
List *indexorderby, List *indexorderbyorig,
ScanDirection indexscandir);
ScanDirection indexscandir, bool indexonly);
static BitmapIndexScan *make_bitmap_indexscan(Index scanrelid, Oid indexid,
List *indexqual,
List *indexqualorig);
@ -1183,7 +1183,8 @@ create_indexscan_plan(PlannerInfo *root,
stripped_indexquals,
fixed_indexorderbys,
indexorderbys,
best_path->indexscandir);
best_path->indexscandir,
best_path->indexonly);
copy_path_costsize(&scan_plan->scan.plan, &best_path->path);
/* use the indexscan-specific rows estimate, not the parent rel's */
@ -2841,7 +2842,8 @@ make_indexscan(List *qptlist,
List *indexqualorig,
List *indexorderby,
List *indexorderbyorig,
ScanDirection indexscandir)
ScanDirection indexscandir,
bool indexonly)
{
IndexScan *node = makeNode(IndexScan);
Plan *plan = &node->scan.plan;
@ -2858,6 +2860,7 @@ make_indexscan(List *qptlist,
node->indexorderby = indexorderby;
node->indexorderbyorig = indexorderbyorig;
node->indexorderdir = indexscandir;
node->indexonly = indexonly;
return node;
}