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Redo postgres_fdw's planner code so it can handle parameterized paths.

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I wasn't going to ship this without having at least some example of how
to do that.  This version isn't terribly bright; in particular it won't
consider any combinations of multiple join clauses.  Given the cost of
executing a remote EXPLAIN, I'm not sure we want to be very aggressive
about doing that, anyway.

In support of this, refactor generate_implied_equalities_for_indexcol
so that it can be used to extract equivalence clauses that aren't
necessarily tied to an index.
This commit is contained in:
Tom Lane
2013-03-21 19:43:59 -04:00
parent 08af1a0a2a
commit 9cbc4b80dd
8 changed files with 943 additions and 577 deletions
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41
src/backend/optimizer/path/indxpath.c
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@@ -78,6 +78,13 @@ typedef struct
Bitmapset *clauseids; /* quals+preds represented as a bitmapset */
} PathClauseUsage;
/* Callback argument for ec_member_matches_indexcol */
typedef struct
{
IndexOptInfo *index; /* index we're considering */
int indexcol; /* index column we want to match to */
} ec_member_matches_arg;
static void consider_index_join_clauses(PlannerInfo *root, RelOptInfo *rel,
IndexOptInfo *index,
@@ -162,6 +169,9 @@ static void match_pathkeys_to_index(IndexOptInfo *index, List *pathkeys,
List **clause_columns_p);
static Expr *match_clause_to_ordering_op(IndexOptInfo *index,
int indexcol, Expr *clause, Oid pk_opfamily);
static bool ec_member_matches_indexcol(PlannerInfo *root, RelOptInfo *rel,
EquivalenceClass *ec, EquivalenceMember *em,
void *arg);
static bool match_boolean_index_clause(Node *clause, int indexcol,
IndexOptInfo *index);
static bool match_special_index_operator(Expr *clause,
@@ -645,7 +655,7 @@ get_join_index_paths(PlannerInfo *root, RelOptInfo *rel,
/*
* Add applicable eclass join clauses. The clauses generated for each
* column are redundant (cf generate_implied_equalities_for_indexcol),
* column are redundant (cf generate_implied_equalities_for_column),
* so we need at most one. This is the only exception to the general
* rule of using all available index clauses.
*/
@@ -1992,18 +2002,22 @@ match_eclass_clauses_to_index(PlannerInfo *root, IndexOptInfo *index,
for (indexcol = 0; indexcol < index->ncolumns; indexcol++)
{
ec_member_matches_arg arg;
List *clauses;
/* Generate clauses, skipping any that join to lateral_referencers */
clauses = generate_implied_equalities_for_indexcol(root,
index,
indexcol,
lateral_referencers);
arg.index = index;
arg.indexcol = indexcol;
clauses = generate_implied_equalities_for_column(root,
index->rel,
ec_member_matches_indexcol,
(void *) &arg,
lateral_referencers);
/*
* We have to check whether the results actually do match the index,
* since for non-btree indexes the EC's equality operators might not
* be in the index opclass (cf eclass_member_matches_indexcol).
* be in the index opclass (cf ec_member_matches_indexcol).
*/
match_clauses_to_index(index, clauses, clauseset);
}
@@ -2682,15 +2696,18 @@ check_partial_indexes(PlannerInfo *root, RelOptInfo *rel)
****************************************************************************/
/*
* eclass_member_matches_indexcol
* ec_member_matches_indexcol
* Test whether an EquivalenceClass member matches an index column.
*
* This is exported for use by generate_implied_equalities_for_indexcol.
* This is a callback for use by generate_implied_equalities_for_column.
*/
bool
eclass_member_matches_indexcol(EquivalenceClass *ec, EquivalenceMember *em,
IndexOptInfo *index, int indexcol)
static bool
ec_member_matches_indexcol(PlannerInfo *root, RelOptInfo *rel,
EquivalenceClass *ec, EquivalenceMember *em,
void *arg)
{
IndexOptInfo *index = ((ec_member_matches_arg *) arg)->index;
int indexcol = ((ec_member_matches_arg *) arg)->indexcol;
Oid curFamily = index->opfamily[indexcol];
Oid curCollation = index->indexcollations[indexcol];
@@ -2701,7 +2718,7 @@ eclass_member_matches_indexcol(EquivalenceClass *ec, EquivalenceMember *em,
* whether clauses generated from the EC could be used with the index, so
* don't check the opfamily. This might mean we return "true" for a
* useless EC, so we have to recheck the results of
* generate_implied_equalities_for_indexcol; see
* generate_implied_equalities_for_column; see
* match_eclass_clauses_to_index.
*/
if (index->relam == BTREE_AM_OID &&