diff options
| author | Tom Lane | 2010-11-19 22:31:50 +0000 |
|---|---|---|
| committer | Tom Lane | 2010-11-19 22:31:50 +0000 |
| commit | 0f61d4dd1b4f95832dcd81c9688dac56fd6b5687 (patch) | |
| tree | 9bb1e825dc323f19cc1969b1bcbdfd13b80fce98 /src/include/optimizer | |
| parent | fe24d781612700646bfb3e08925e34c43926f9df (diff) | |
Improve relation width estimation for subqueries.
As per the ancient comment for set_rel_width, it really wasn't much good
for relations that aren't plain tables: it would never find any stats and
would always fall back on datatype-based estimates, which are often pretty
silly. Fix that by copying up width estimates from the subquery planning
process.
At some point we might want to do this for CTEs too, but that would be a
significantly more invasive patch because the sub-PlannerInfo is no longer
accessible by the time it's needed. I refrained from doing anything about
that, partly for fear of breaking the unmerged CTE-related patches.
In passing, also generate less bogus width estimates for whole-row Vars.
Per a gripe from Jon Nelson.
Diffstat (limited to 'src/include/optimizer')
| -rw-r--r-- | src/include/optimizer/cost.h | 2 | ||||
| -rw-r--r-- | src/include/optimizer/plancat.h | 2 |
2 files changed, 3 insertions, 1 deletions
diff --git a/src/include/optimizer/cost.h b/src/include/optimizer/cost.h index e1dcd6df14..8df1b95abe 100644 --- a/src/include/optimizer/cost.h +++ b/src/include/optimizer/cost.h @@ -121,6 +121,8 @@ extern void set_joinrel_size_estimates(PlannerInfo *root, RelOptInfo *rel, RelOptInfo *inner_rel, SpecialJoinInfo *sjinfo, List *restrictlist); +extern void set_subquery_size_estimates(PlannerInfo *root, RelOptInfo *rel, + PlannerInfo *subroot); extern void set_function_size_estimates(PlannerInfo *root, RelOptInfo *rel); extern void set_values_size_estimates(PlannerInfo *root, RelOptInfo *rel); extern void set_cte_size_estimates(PlannerInfo *root, RelOptInfo *rel, diff --git a/src/include/optimizer/plancat.h b/src/include/optimizer/plancat.h index de7de84cb3..ca7b2c6469 100644 --- a/src/include/optimizer/plancat.h +++ b/src/include/optimizer/plancat.h @@ -31,7 +31,7 @@ extern void get_relation_info(PlannerInfo *root, Oid relationObjectId, extern void estimate_rel_size(Relation rel, int32 *attr_widths, BlockNumber *pages, double *tuples); -extern int32 get_relation_data_width(Oid relid); +extern int32 get_relation_data_width(Oid relid, int32 *attr_widths); extern bool relation_excluded_by_constraints(PlannerInfo *root, RelOptInfo *rel, RangeTblEntry *rte); |