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into an OR of equality comparisons, rather than x = ANY(ARRAY[...]), when there are Vars in the right-hand side. This avoids a performance regression compared to pre-8.2 releases, in cases where the OR form can be optimized into scans of multiple indexes. Limit the possible downside by preferring this form only when the list isn't very long (I set the cutoff at 32 elements, which is a bit arbitrary but in the right ballpark). Per discussion with Jim Nasby. In passing, also make it try the OR form if it cannot select a common type for the array elements; we've seen a complaint or two about how the OR form worked for such cases and ARRAY doesn't. |
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| .. | ||
| .cvsignore | ||
| analyze.c | ||
| gram.y | ||
| keywords.c | ||
| Makefile | ||
| parse_agg.c | ||
| parse_clause.c | ||
| parse_coerce.c | ||
| parse_cte.c | ||
| parse_expr.c | ||
| parse_func.c | ||
| parse_node.c | ||
| parse_oper.c | ||
| parse_relation.c | ||
| parse_target.c | ||
| parse_type.c | ||
| parse_utilcmd.c | ||
| parser.c | ||
| README | ||
| scan.l | ||
| scansup.c | ||
$PostgreSQL: pgsql/src/backend/parser/README,v 1.10 2008/04/09 01:00:46 momjian Exp $ Parser ====== This directory does more than tokenize and parse SQL queries. It also creates Query structures for the various complex queries that are passed to the optimizer and then executor. parser.c things start here scan.l break query into tokens scansup.c handle escapes in input strings keywords.c turn keywords into specific tokens gram.y parse the tokens and fill query-type-specific structures analyze.c top level of parse analysis for optimizable queries parse_clause.c handle clauses like WHERE, ORDER BY, GROUP BY, ... parse_coerce.c handle coercing expressions to different data types parse_expr.c handle expressions like col, col + 3, x = 3 or x = 4 parse_oper.c handle operators in expressions parse_agg.c handle aggregates, like SUM(col1), AVG(col2), ... parse_func.c handle functions, table.column and column identifiers parse_node.c create nodes for various structures parse_target.c handle the result list of the query parse_relation.c support routines for tables and column handling parse_type.c support routines for data type handling parse_utilcmd.c parse analysis for utility commands (done at execution time)