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| author | Peter Eisentraut <peter@eisentraut.org> | 2021-02-01 13:54:59 +0100 |
|---|---|---|
| committer | Peter Eisentraut <peter@eisentraut.org> | 2021-02-01 14:32:51 +0100 |
| commit | 3696a600e2292d43c00949ddf0352e4ebb487e5b (patch) | |
| tree | 11f19c8c9e5757c44b8da02d0e1f7b41f8ec5f13 /src/backend/parser/analyze.c | |
| parent | bb513b364b4fe31574574c8d0afbb2255268b321 (diff) | |
| download | postgresql-3696a600e2292d43c00949ddf0352e4ebb487e5b.tar.gz postgresql-3696a600e2292d43c00949ddf0352e4ebb487e5b.zip | |
SEARCH and CYCLE clauses
This adds the SQL standard feature that adds the SEARCH and CYCLE
clauses to recursive queries to be able to do produce breadth- or
depth-first search orders and detect cycles. These clauses can be
rewritten into queries using existing syntax, and that is what this
patch does in the rewriter.
Reviewed-by: Vik Fearing <vik@postgresfriends.org>
Reviewed-by: Pavel Stehule <pavel.stehule@gmail.com>
Discussion: https://www.postgresql.org/message-id/flat/db80ceee-6f97-9b4a-8ee8-3ba0c58e5be2@2ndquadrant.com
Diffstat (limited to 'src/backend/parser/analyze.c')
| -rw-r--r-- | src/backend/parser/analyze.c | 47 |
1 files changed, 29 insertions, 18 deletions
diff --git a/src/backend/parser/analyze.c b/src/backend/parser/analyze.c index 65483892252..0f3a70c49a8 100644 --- a/src/backend/parser/analyze.c +++ b/src/backend/parser/analyze.c @@ -1810,6 +1810,33 @@ transformSetOperationStmt(ParseState *pstate, SelectStmt *stmt) } /* + * Make a SortGroupClause node for a SetOperationStmt's groupClauses + */ +SortGroupClause * +makeSortGroupClauseForSetOp(Oid rescoltype) +{ + SortGroupClause *grpcl = makeNode(SortGroupClause); + Oid sortop; + Oid eqop; + bool hashable; + + /* determine the eqop and optional sortop */ + get_sort_group_operators(rescoltype, + false, true, false, + &sortop, &eqop, NULL, + &hashable); + + /* we don't have a tlist yet, so can't assign sortgrouprefs */ + grpcl->tleSortGroupRef = 0; + grpcl->eqop = eqop; + grpcl->sortop = sortop; + grpcl->nulls_first = false; /* OK with or without sortop */ + grpcl->hashable = hashable; + + return grpcl; +} + +/* * transformSetOperationTree * Recursively transform leaves and internal nodes of a set-op tree * @@ -2109,31 +2136,15 @@ transformSetOperationTree(ParseState *pstate, SelectStmt *stmt, */ if (op->op != SETOP_UNION || !op->all) { - SortGroupClause *grpcl = makeNode(SortGroupClause); - Oid sortop; - Oid eqop; - bool hashable; ParseCallbackState pcbstate; setup_parser_errposition_callback(&pcbstate, pstate, bestlocation); - /* determine the eqop and optional sortop */ - get_sort_group_operators(rescoltype, - false, true, false, - &sortop, &eqop, NULL, - &hashable); + op->groupClauses = lappend(op->groupClauses, + makeSortGroupClauseForSetOp(rescoltype)); cancel_parser_errposition_callback(&pcbstate); - - /* we don't have a tlist yet, so can't assign sortgrouprefs */ - grpcl->tleSortGroupRef = 0; - grpcl->eqop = eqop; - grpcl->sortop = sortop; - grpcl->nulls_first = false; /* OK with or without sortop */ - grpcl->hashable = hashable; - - op->groupClauses = lappend(op->groupClauses, grpcl); } /* |