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| author | Tom Lane <tgl@sss.pgh.pa.us> | 2003-03-14 00:55:17 +0000 |
|---|---|---|
| committer | Tom Lane <tgl@sss.pgh.pa.us> | 2003-03-14 00:55:17 +0000 |
| commit | 7931bfa764d114ed64cc24bbeb3876206f2e2ec4 (patch) | |
| tree | 0c8abc0ae204cdc671a34f132357b628746fc6d0 | |
| parent | 2a1ef30b5779edb9acd1bb69e9d4f4e1c7889f9e (diff) | |
| download | postgresql-7931bfa764d114ed64cc24bbeb3876206f2e2ec4.tar.gz postgresql-7931bfa764d114ed64cc24bbeb3876206f2e2ec4.zip | |
Make eval_const_expressions simplify FieldSelect from a whole-row Var
into an ordinary one-field Var. Per example from Chris Mungall.
| -rw-r--r-- | src/backend/optimizer/util/clauses.c | 24 |
1 files changed, 23 insertions, 1 deletions
diff --git a/src/backend/optimizer/util/clauses.c b/src/backend/optimizer/util/clauses.c index fcd58374189..bdad4d9b811 100644 --- a/src/backend/optimizer/util/clauses.c +++ b/src/backend/optimizer/util/clauses.c @@ -8,7 +8,7 @@ * * * IDENTIFICATION - * $Header: /cvsroot/pgsql/src/backend/optimizer/util/clauses.c,v 1.131 2003/03/10 03:53:50 tgl Exp $ + * $Header: /cvsroot/pgsql/src/backend/optimizer/util/clauses.c,v 1.132 2003/03/14 00:55:17 tgl Exp $ * * HISTORY * AUTHOR DATE MAJOR EVENT @@ -1497,6 +1497,28 @@ eval_const_expressions_mutator(Node *node, List *active_fns) newcoalesce->args = newargs; return (Node *) newcoalesce; } + if (IsA(node, FieldSelect)) + { + /* + * We can optimize field selection from a whole-row Var into a + * simple Var. (This case won't be generated directly by the + * parser, because ParseComplexProjection short-circuits it. + * But it can arise while simplifying functions.) If the argument + * isn't a whole-row Var, just fall through to do generic processing. + */ + FieldSelect *fselect = (FieldSelect *) node; + Var *argvar = (Var *) fselect->arg; + + if (argvar && IsA(argvar, Var) && + argvar->varattno == InvalidAttrNumber) + { + return (Node *) makeVar(argvar->varno, + fselect->fieldnum, + fselect->resulttype, + fselect->resulttypmod, + argvar->varlevelsup); + } + } /* * For any node type not handled above, we recurse using |