On 4/3/24 01:22, Tomas Vondra wrote:
Cool! There's obviously no chance to get this into v18, and I have stuff
to do in this CF. But I'll take a look after that.
I'm looking at your patch now - an excellent start to an eagerly awaited
feature!
A couple of questions:
1. I didn't find the implementation of strategy 'c' - estimation by the
number of distinct values. Do you forget it?
2. Can we add a clauselist selectivity hook into the core (something
similar the code in attachment)? It can allow the development and
testing of multicolumn join estimations without patching the core.
--
regards,
Andrei Lepikhov
Postgres Professional
diff --git a/src/backend/optimizer/path/clausesel.c b/src/backend/optimizer/path/clausesel.c
index 0ab021c1e8..271d36a522 100644
--- a/src/backend/optimizer/path/clausesel.c
+++ b/src/backend/optimizer/path/clausesel.c
@@ -128,6 +128,9 @@ clauselist_selectivity_ext(PlannerInfo *root,
ListCell *l;
int listidx;
+ if (clauselist_selectivity_hook)
+ s1 = clauselist_selectivity_hook(root, clauses, varRelid, jointype,
+ sjinfo, &estimatedclauses);
/*
* If there's exactly one clause, just go directly to
* clause_selectivity_ext(). None of what we might do below is relevant.
diff --git a/src/backend/utils/adt/selfuncs.c b/src/backend/utils/adt/selfuncs.c
index 5f5d7959d8..ff98fda08c 100644
--- a/src/backend/utils/adt/selfuncs.c
+++ b/src/backend/utils/adt/selfuncs.c
@@ -146,6 +146,7 @@
/* Hooks for plugins to get control when we ask for stats */
get_relation_stats_hook_type get_relation_stats_hook = NULL;
get_index_stats_hook_type get_index_stats_hook = NULL;
+clauselist_selectivity_hook_type clauselist_selectivity_hook = NULL;
static double eqsel_internal(PG_FUNCTION_ARGS, bool negate);
static double eqjoinsel_inner(Oid opfuncoid, Oid collation,
diff --git a/src/include/utils/selfuncs.h b/src/include/utils/selfuncs.h
index f2563ad1cb..ee28d3ba9b 100644
--- a/src/include/utils/selfuncs.h
+++ b/src/include/utils/selfuncs.h
@@ -148,6 +148,15 @@ typedef bool (*get_index_stats_hook_type) (PlannerInfo *root,
VariableStatData *vardata);
extern PGDLLIMPORT get_index_stats_hook_type get_index_stats_hook;
+/* Hooks for plugins to get control when we ask for selectivity estimation */
+typedef bool (*clauselist_selectivity_hook_type) (PlannerInfo *root,
+ List *clauses,
+ int varRelid,
+ JoinType jointype,
+ SpecialJoinInfo *sjinfo,
+ Bitmapset **estimatedclauses);
+extern PGDLLIMPORT clauselist_selectivity_hook_type clauselist_selectivity_hook;
+
/* Functions in selfuncs.c */
extern void examine_variable(PlannerInfo *root, Node *node, int varRelid,
