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SQL has standardized on => as the use of to specify named parameters, and we've wanted for many years to support the same syntax ourselves, but this has been complicated by the possible use of => as an operator name. In PostgreSQL 9.0, we began emitting a warning when an operator named => was defined, and in PostgreSQL 9.2, we stopped shipping a =>(text, text) operator as part of hstore. By the time the next major version of PostgreSQL is released, => will have been deprecated for a full five years, so hopefully there won't be too many people still relying on it. We continue to support := for compatibility with previous PostgreSQL releases. Pavel Stehule, reviewed by Petr Jelinek, with a few documentation tweaks by me. |
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| .. | ||
| .gitignore | ||
| analyze.c | ||
| check_keywords.pl | ||
| gram.y | ||
| keywords.c | ||
| kwlookup.c | ||
| Makefile | ||
| parse_agg.c | ||
| parse_clause.c | ||
| parse_coerce.c | ||
| parse_collate.c | ||
| parse_cte.c | ||
| parse_expr.c | ||
| parse_func.c | ||
| parse_node.c | ||
| parse_oper.c | ||
| parse_param.c | ||
| parse_relation.c | ||
| parse_target.c | ||
| parse_type.c | ||
| parse_utilcmd.c | ||
| parser.c | ||
| README | ||
| scan.l | ||
| scansup.c | ||
src/backend/parser/README 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 kwlookup.c turn keywords into specific tokens keywords.c table of standard keywords (passed to kwlookup.c) gram.y parse the tokens and produce a "raw" parse tree analyze.c top level of parse analysis for optimizable queries parse_agg.c handle aggregates, like SUM(col1), AVG(col2), ... parse_clause.c handle clauses like WHERE, ORDER BY, GROUP BY, ... parse_coerce.c handle coercing expressions to different data types parse_collate.c assign collation information in completed expressions parse_cte.c handle Common Table Expressions (WITH clauses) parse_expr.c handle expressions like col, col + 3, x = 3 or x = 4 parse_func.c handle functions, table.column and column identifiers parse_node.c create nodes for various structures parse_oper.c handle operators in expressions parse_param.c handle Params (for the cases used in the core backend) parse_relation.c support routines for tables and column handling parse_target.c handle the result list of the query parse_type.c support routines for data type handling parse_utilcmd.c parse analysis for utility commands (done at execution time)