diff options
Diffstat (limited to 'src/backend/parser/gram.y')
| -rw-r--r-- | src/backend/parser/gram.y | 21 |
1 files changed, 12 insertions, 9 deletions
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y index d6fc0b0a62..b14fde0799 100644 --- a/src/backend/parser/gram.y +++ b/src/backend/parser/gram.y @@ -11,7 +11,7 @@ * * * IDENTIFICATION - * $Header: /cvsroot/pgsql/src/backend/parser/gram.y,v 2.149 2000/02/22 00:05:04 tgl Exp $ + * $Header: /cvsroot/pgsql/src/backend/parser/gram.y,v 2.150 2000/02/24 01:59:17 tgl Exp $ * * HISTORY * AUTHOR DATE MAJOR EVENT @@ -5606,14 +5606,17 @@ Oid param_type(int t) } /* - * The optimizer doesn't like '-' 4 for index use. It only checks for - * Var '=' Const. It wants an integer of -4, so we try to merge the - * minus into the constant. - * - * This code is no longer essential as of 10/1999, since the optimizer - * now has a constant-subexpression simplifier. However, we can save - * a few cycles throughout the parse and rewrite stages if we collapse - * the minus into the constant sooner rather than later... + * doNegate --- handle negation of a numeric constant. + * + * Formerly, we did this here because the optimizer couldn't cope with + * indexquals that looked like "var = -4" --- it wants "var = const" + * and a unary minus operator applied to a constant didn't qualify. + * As of Postgres 7.0, that problem doesn't exist anymore because there + * is a constant-subexpression simplifier in the optimizer. However, + * there's still a good reason for doing this here, which is that we can + * postpone committing to a particular internal representation for simple + * negative constants. It's better to leave "-123.456" in string form + * until we know what the desired type is. */ static Node * doNegate(Node *n) |