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648bd05b13
Although the SQL spec forbids duplicate table aliases, historically
we've allowed queries like
SELECT ... FROM tab1 x CROSS JOIN (tab2 x CROSS JOIN tab3 y) z
on the grounds that the aliased join (z) hides the aliases within it,
therefore there is no conflict between the two RTEs named "x". The
LATERAL patch broke this, on the misguided basis that "x" could be
ambiguous if tab3 were a LATERAL subquery. To avoid breaking existing
queries, it's better to allow this situation and complain only if
tab3 actually does contain an ambiguous reference. We need only remove
the check that was throwing an error, because the column lookup code
is already prepared to handle ambiguous references. Per bug #8444.
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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)