database/postgres
1
0
Fork 0
mirror of https://github.com/postgres/postgres.git synced 2025-11-21 00:42:43 +03:00
Code Activity

Improve my initial, rather hacky implementation of joins to append

Browse Source 
relations: fix the executor so that we can have an Append plan on the
inside of a nestloop and still pass down outer index keys to index scans
within the Append, then generate such plans as if they were regular
inner indexscans.  This avoids the need to evaluate the outer relation
multiple times.
This commit is contained in:
Tom Lane
2006-02-05 02:59:17 +00:00
parent 354213c7f4
commit 336a6491aa
8 changed files with 114 additions and 273 deletions
Download Patch File Download Diff File Expand all files Collapse all files

47
src/backend/optimizer/path/costsize.c
View File

@@ -49,7 +49,7 @@
* Portions Copyright (c) 1994, Regents of the University of California
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/optimizer/path/costsize.c,v 1.152 2005/12/28 01:29:59 tgl Exp $
* $PostgreSQL: pgsql/src/backend/optimizer/path/costsize.c,v 1.153 2006/02/05 02:59:16 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@@ -991,6 +991,38 @@ cost_group(Path *path, PlannerInfo *root,
path->total_cost = total_cost;
}
/*
* If a nestloop's inner path is an indexscan, be sure to use its estimated
* output row count, which may be lower than the restriction-clause-only row
* count of its parent. (We don't include this case in the PATH_ROWS macro
* because it applies *only* to a nestloop's inner relation.) We have to
* be prepared to recurse through Append nodes in case of an appendrel.
*/
static double
nestloop_inner_path_rows(Path *path)
{
double result;
if (IsA(path, IndexPath))
result = ((IndexPath *) path)->rows;
else if (IsA(path, BitmapHeapPath))
result = ((BitmapHeapPath *) path)->rows;
else if (IsA(path, AppendPath))
{
ListCell *l;
result = 0;
foreach(l, ((AppendPath *) path)->subpaths)
{
result += nestloop_inner_path_rows((Path *) lfirst(l));
}
}
else
result = PATH_ROWS(path);
return result;
}
/*
* cost_nestloop
* Determines and returns the cost of joining two relations using the
@@ -1008,21 +1040,10 @@ cost_nestloop(NestPath *path, PlannerInfo *root)
Cost cpu_per_tuple;
QualCost restrict_qual_cost;
double outer_path_rows = PATH_ROWS(outer_path);
double inner_path_rows = PATH_ROWS(inner_path);
double inner_path_rows = nestloop_inner_path_rows(inner_path);
double ntuples;
Selectivity joininfactor;
/*
* If inner path is an indexscan, be sure to use its estimated output row
* count, which may be lower than the restriction-clause-only row count of
* its parent. (We don't include this case in the PATH_ROWS macro because
* it applies *only* to a nestloop's inner relation.)
*/
if (IsA(inner_path, IndexPath))
inner_path_rows = ((IndexPath *) inner_path)->rows;
else if (IsA(inner_path, BitmapHeapPath))
inner_path_rows = ((BitmapHeapPath *) inner_path)->rows;
if (!enable_nestloop)
startup_cost += disable_cost;