postgresql/src/backend/parser
Andrew Gierth 409230a721 Postpone aggregate checks until after collation is assigned.
Previously, parseCheckAggregates was run before
assign_query_collations, but this causes problems if any expression
has already had a collation assigned by some transform function (e.g.
transformCaseExpr) before parseCheckAggregates runs. The differing
collations would cause expressions not to be recognized as equal to
the ones in the GROUP BY clause, leading to spurious errors about
unaggregated column references.

The result was that CASE expr WHEN val ... would fail when "expr"
contained a GROUPING() expression or matched one of the group by
expressions, and where collatable types were involved; whereas the
supposedly identical CASE WHEN expr = val ... would succeed.

Backpatch all the way; this appears to have been wrong ever since
collations were introduced.

Per report from Guillaume Lelarge, analysis and patch by me.

Discussion: https://postgr.es/m/CAECtzeVSO_US8C2Khgfv54ZMUOBR4sWq+6_bLrETnWExHT=rFg@mail.gmail.com
Discussion: https://postgr.es/m/87muo0k0c7.fsf@news-spur.riddles.org.uk
2019-01-17 06:25:55 +00:00
..
.gitignore Convert cvsignore to gitignore, and add .gitignore for build targets. 2010-09-22 12:57:04 +02:00
analyze.c Postpone aggregate checks until after collation is assigned. 2019-01-17 06:25:55 +00:00
check_keywords.pl Post-PG 10 beta1 pgperltidy run 2017-05-17 19:01:23 -04:00
gram.y Revise attribute handling code on partition creation 2018-11-08 16:22:09 -03:00
Makefile Fix make rules that generate multiple output files. 2018-03-23 13:45:38 -04:00
parse_agg.c Re-allow SRFs and window functions within sub-selects within aggregates. 2017-06-27 17:51:11 -04:00
parse_clause.c Fix parsetree representation of XMLTABLE(XMLNAMESPACES(DEFAULT ...)). 2018-09-17 13:16:32 -04:00
parse_coerce.c Phase 3 of pgindent updates. 2017-06-21 15:35:54 -04:00
parse_collate.c Phase 3 of pgindent updates. 2017-06-21 15:35:54 -04:00
parse_cte.c Phase 3 of pgindent updates. 2017-06-21 15:35:54 -04:00
parse_enr.c Add infrastructure to support EphemeralNamedRelation references. 2017-03-31 23:17:18 -05:00
parse_expr.c Phase 3 of pgindent updates. 2017-06-21 15:35:54 -04:00
parse_func.c Phase 3 of pgindent updates. 2017-06-21 15:35:54 -04:00
parse_node.c Phase 3 of pgindent updates. 2017-06-21 15:35:54 -04:00
parse_oper.c Phase 3 of pgindent updates. 2017-06-21 15:35:54 -04:00
parse_param.c Phase 3 of pgindent updates. 2017-06-21 15:35:54 -04:00
parse_relation.c Dept of second thoughts: keep aliasp_item in sync with tlistitem. 2017-10-27 18:16:25 -04:00
parse_target.c Clean up handling of dropped columns in NAMEDTUPLESTORE RTEs. 2017-09-06 10:41:05 -04:00
parse_type.c Phase 3 of pgindent updates. 2017-06-21 15:35:54 -04:00
parse_utilcmd.c Revise attribute handling code on partition creation 2018-11-08 16:22:09 -03:00
parser.c Change representation of statement lists, and add statement location info. 2017-01-14 16:02:35 -05:00
README Move keywords.c/kwlookup.c into src/common/. 2016-03-23 20:22:08 -04:00
scan.l Fix lexing of standard multi-character operators in edge cases. 2018-08-23 21:43:55 +01:00
scansup.c Update copyright via script for 2017 2017-01-03 13:48:53 -05:00

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
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)

See also src/common/keywords.c, which contains the table of standard
keywords and the keyword lookup function.  We separated that out because
various frontend code wants to use it too.