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columns of the grouping clause to avoid redundant sorts. The optimizer is not currently capable of doing this, so this patch implements a simple hack in the analysis phase (transformGroupClause): if any subset of the GROUP BY clause matches a prefix of the ORDER BY list, that prefix is moved to the front of the GROUP BY clause. This shouldn't change the semantics of the query, and allows a redundant sort to be avoided for queries like "GROUP BY a, b ORDER BY b". |
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| .. | ||
| .cvsignore | ||
| analyze.c | ||
| gram.y | ||
| keywords.c | ||
| Makefile | ||
| parse_agg.c | ||
| parse_clause.c | ||
| parse_coerce.c | ||
| parse_expr.c | ||
| parse_func.c | ||
| parse_node.c | ||
| parse_oper.c | ||
| parse_relation.c | ||
| parse_target.c | ||
| parse_type.c | ||
| parser.c | ||
| README | ||
| scan.l | ||
| scansup.c | ||
This directory does more than tokenize and parse SQL queries. It also creates Query structures for the various complex queries that is passed to the optimizer and then executor. parser.c things start here scan.l break query into tokens scansup.c handle escapes in input keywords.c turn keywords into specific tokens gram.y parse the tokens and fill query-type-specific structures analyze.c handle post-parse processing for each query type parse_clause.c handle clauses like WHERE, ORDER BY, GROUP BY, ... parse_coerce.c used for coercing expressions of different types parse_expr.c handle expressions like col, col + 3, x = 3 or x = 4 parse_oper.c handle operations 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 type handling