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| author | Tom Lane <tgl@sss.pgh.pa.us> | 2022-08-17 15:35:51 -0400 |
|---|---|---|
| committer | Tom Lane <tgl@sss.pgh.pa.us> | 2022-08-17 15:35:51 -0400 |
| commit | 6569ca43973b754e8213072c8ddcae9e7baf2aaa (patch) | |
| tree | 396627f9ae41b4bd5f069cd20c142d30d62b8b59 /src/backend/optimizer/util/var.c | |
| parent | efd0c16becbf45e3b0215e124fde75fee8fcbce4 (diff) | |
| download | postgresql-6569ca43973b754e8213072c8ddcae9e7baf2aaa.tar.gz postgresql-6569ca43973b754e8213072c8ddcae9e7baf2aaa.zip | |
Make PlaceHolderInfo lookup O(1).
Up to now we've just searched the placeholder_list when we want to
find the PlaceHolderInfo with a given ID. While there's no evidence
of that being a problem in the field, an upcoming patch will add
find_placeholder_info() calls in build_joinrel_tlist(), which seems
likely to make it more of an issue: a joinrel emitting lots of
PlaceHolderVars would incur O(N^2) cost, and we might be building
a lot of joinrels in complex queries. Hence, add an array that
can be indexed directly by phid to make the lookups constant-time.
Discussion: https://postgr.es/m/1405792.1660677844@sss.pgh.pa.us
Diffstat (limited to 'src/backend/optimizer/util/var.c')
| -rw-r--r-- | src/backend/optimizer/util/var.c | 11 |
1 files changed, 2 insertions, 9 deletions
diff --git a/src/backend/optimizer/util/var.c b/src/backend/optimizer/util/var.c index ebc6ce84b0b..7db86c39efc 100644 --- a/src/backend/optimizer/util/var.c +++ b/src/backend/optimizer/util/var.c @@ -210,15 +210,8 @@ pull_varnos_walker(Node *node, pull_varnos_context *context) if (phv->phlevelsup == 0) { - ListCell *lc; - - foreach(lc, context->root->placeholder_list) - { - phinfo = (PlaceHolderInfo *) lfirst(lc); - if (phinfo->phid == phv->phid) - break; - phinfo = NULL; - } + if (phv->phid < context->root->placeholder_array_size) + phinfo = context->root->placeholder_array[phv->phid]; } if (phinfo == NULL) { |