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| author | Peter Eisentraut <peter@eisentraut.org> | 2021-03-31 17:09:24 +0200 |
|---|---|---|
| committer | Peter Eisentraut <peter@eisentraut.org> | 2021-03-31 17:10:50 +0200 |
| commit | 055fee7eb4dcc78e58672aef146334275e1cc40d (patch) | |
| tree | 2034e69c471453e9aea59712b09d3fed95bce330 /src/backend/parser/parse_relation.c | |
| parent | 27e1f14563cf982f1f4d71e21ef247866662a052 (diff) | |
| download | postgresql-055fee7eb4dcc78e58672aef146334275e1cc40d.tar.gz postgresql-055fee7eb4dcc78e58672aef146334275e1cc40d.zip | |
Allow an alias to be attached to a JOIN ... USING
This allows something like
SELECT ... FROM t1 JOIN t2 USING (a, b, c) AS x
where x has the columns a, b, c and unlike a regular alias it does not
hide the range variables of the tables being joined t1 and t2.
Per SQL:2016 feature F404 "Range variable for common column names".
Reviewed-by: Vik Fearing <vik.fearing@2ndquadrant.com>
Reviewed-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://www.postgresql.org/message-id/flat/454638cf-d563-ab76-a585-2564428062af@2ndquadrant.com
Diffstat (limited to 'src/backend/parser/parse_relation.c')
| -rw-r--r-- | src/backend/parser/parse_relation.c | 8 |
1 files changed, 8 insertions, 0 deletions
diff --git a/src/backend/parser/parse_relation.c b/src/backend/parser/parse_relation.c index b12416535ed..d451f055f72 100644 --- a/src/backend/parser/parse_relation.c +++ b/src/backend/parser/parse_relation.c @@ -753,6 +753,12 @@ scanNSItemForColumn(ParseState *pstate, ParseNamespaceItem *nsitem, * else return InvalidAttrNumber. * If the name proves ambiguous within this RTE, raise error. * + * Actually, we only search the names listed in "eref". This can be either + * rte->eref, in which case we are indeed searching all the column names, + * or for a join it can be rte->join_using_alias, in which case we are only + * considering the common column names (which are the first N columns of the + * join, so everything works). + * * pstate and location are passed only for error-reporting purposes. * * Side effect: if fuzzystate is non-NULL, check non-system columns @@ -2134,6 +2140,7 @@ addRangeTableEntryForJoin(ParseState *pstate, List *aliasvars, List *leftcols, List *rightcols, + Alias *join_using_alias, Alias *alias, bool inFromCl) { @@ -2162,6 +2169,7 @@ addRangeTableEntryForJoin(ParseState *pstate, rte->joinaliasvars = aliasvars; rte->joinleftcols = leftcols; rte->joinrightcols = rightcols; + rte->join_using_alias = join_using_alias; rte->alias = alias; eref = alias ? copyObject(alias) : makeAlias("unnamed_join", NIL); |