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Fix set_rel_width() to do something reasonable with non-Var items in a

2009年7月11日 04:09:33 +0000 (04:09 +0000)

RelOptInfo targetlist. It used to be that the only possibility other than
a Var was a RowExpr representing a whole-row child Var, but as of 8.4's
expanded ability to flatten appendrel members, we can get arbitrary expressions
in there. Use the expression's type info and get_typavgwidth() to produce
an at-least-marginally-sane result. Note that get_typavgwidth()'s fallback
estimate (32 bytes) is the same as what was here before, so there will be
no behavioral change for RowExprs. Noted while looking at recent gripe
about constant quals pushed down to FunctionScan appendrel members ...
not only were we failing to recognize the constant qual, we were getting
the width estimate wrong :-(

src/backend/optimizer/path/costsize.c patch | blob | blame | history

diff --git a/src/backend/optimizer/path/costsize.c b/src/backend/optimizer/path/costsize.c

index 08f1d361bae8b6fdf4d3b827820deabf2b4e2111..1ede488c13b13f910b0d676f6935c9cfeaf9afc6 100644 (file)

--- a/src/backend/optimizer/path/costsize.c

+++ b/src/backend/optimizer/path/costsize.c

@@ -54,7 +54,7 @@

* IDENTIFICATION

- * $PostgreSQL: pgsql/src/backend/optimizer/path/costsize.c,v 1.209 2009年06月11日 14:48:58 momjian Exp $

+ * $PostgreSQL: pgsql/src/backend/optimizer/path/costsize.c,v 1.210 2009年07月11日 04:09:33 tgl Exp $

*-------------------------------------------------------------------------

@@ -2997,8 +2997,16 @@ set_rel_width(PlannerInfo *root, RelOptInfo *rel)

}