mirror of
https://github.com/postgres/postgres.git
synced 2025-11-21 00:42:43 +03:00
ce4f46fdc8
We were setting MERGE source subplan's targetlist by expanding the individual attributes of the source relation completely, early in the parse analysis phase. This failed to work when the condition of an action included a whole-row reference, causing setrefs.c to error out with ERROR: variable not found in subplan target lists because at that point there is nothing to resolve the whole-row reference with. We can fix this by having preprocess_targetlist expand the source targetlist for Vars required from the source rel by all actions. Moreover, by using this expansion mechanism we can do away with the targetlist expansion in transformMergeStmt, which is good because then we no longer pull in columns that aren't needed for anything. Add a test case for the problem. While at it, remove some redundant code in preprocess_targetlist(): MERGE was doing separately what is already being done for UPDATE/DELETE, so we can just rely on the latter and remove the former. (The handling of inherited rels was different for MERGE, but that was a no-longer- necessary hack.) Fix outdated, related comments for fix_join_expr also. Author: Richard Guo <guofenglinux@gmail.com> Author: Álvaro Herrera <alvherre@alvh.no-ip.org> Reported-by: Joe Wildish <joe@lateraljoin.com> Discussion: https://postgr.es/m/fab3b90a-914d-46a9-beb0-df011ee39ee5@www.fastmail.com
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.