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db436adf76
sort order down into planner, instead of handling it only at the very top level of the planner. This fixes many things. An explicit sort is now avoided if there is a cheaper alternative (typically an indexscan) not only for ORDER BY, but also for the internal sort of GROUP BY. It works even when there is no other reason (such as a WHERE condition) to consider the indexscan. It works for indexes on functions. It works for indexes on functions, backwards. It's just so cool... CAUTION: I have changed the representation of SortClause nodes, therefore THIS UPDATE BREAKS STORED RULES. You will need to initdb.
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