diff options
Diffstat (limited to 'src/backend/parser/parse_expr.c')
| -rw-r--r-- | src/backend/parser/parse_expr.c | 39 |
1 files changed, 28 insertions, 11 deletions
diff --git a/src/backend/parser/parse_expr.c b/src/backend/parser/parse_expr.c index ddd041818a5..ced222578db 100644 --- a/src/backend/parser/parse_expr.c +++ b/src/backend/parser/parse_expr.c @@ -8,7 +8,7 @@ * * * IDENTIFICATION - * $PostgreSQL: pgsql/src/backend/parser/parse_expr.c,v 1.235 2008/10/06 17:39:26 tgl Exp $ + * $PostgreSQL: pgsql/src/backend/parser/parse_expr.c,v 1.236 2008/10/25 17:19:09 tgl Exp $ * *------------------------------------------------------------------------- */ @@ -20,6 +20,7 @@ #include "miscadmin.h" #include "nodes/makefuncs.h" #include "nodes/nodeFuncs.h" +#include "optimizer/var.h" #include "parser/analyze.h" #include "parser/parse_coerce.h" #include "parser/parse_expr.h" @@ -974,29 +975,45 @@ transformAExprIn(ParseState *pstate, A_Expr *a) } /* - * If not forced by presence of RowExpr, try to resolve a common scalar - * type for all the expressions, and see if it has an array type. (But if - * there's only one righthand expression, we may as well just fall through - * and generate a simple = comparison.) + * We prefer a boolean tree to ScalarArrayOpExpr if any of these are true: + * + * 1. We have a RowExpr anywhere. + * + * 2. There's only one righthand expression --- best to just generate a + * simple = comparison. + * + * 3. There's a reasonably small number of righthand expressions and + * they contain any Vars. This is a heuristic to support cases like + * WHERE '555-1212' IN (tab.home_phone, tab.work_phone), which can be + * optimized into an OR of indexscans on different indexes so long as + * it's left as an OR tree. (It'd be better to leave this decision + * to the planner, no doubt, but the amount of code required to reformat + * the expression later on seems out of proportion to the benefit.) */ - if (!haveRowExpr && list_length(rexprs) != 1) + if (!(haveRowExpr || + list_length(rexprs) == 1 || + (list_length(rexprs) <= 32 && + contain_vars_of_level((Node *) rexprs, 0)))) { List *allexprs; Oid scalar_type; Oid array_type; /* - * Select a common type for the array elements. Note that since the - * LHS' type is first in the list, it will be preferred when there is - * doubt (eg, when all the RHS items are unknown literals). + * Try to select a common type for the array elements. Note that + * since the LHS' type is first in the list, it will be preferred when + * there is doubt (eg, when all the RHS items are unknown literals). * * Note: use list_concat here not lcons, to avoid damaging rexprs. */ allexprs = list_concat(list_make1(lexpr), rexprs); - scalar_type = select_common_type(pstate, allexprs, "IN", NULL); + scalar_type = select_common_type(pstate, allexprs, NULL, NULL); /* Do we have an array type to use? */ - array_type = get_array_type(scalar_type); + if (OidIsValid(scalar_type)) + array_type = get_array_type(scalar_type); + else + array_type = InvalidOid; if (array_type != InvalidOid) { /* |