database/postgres
1
0
Fork 0
mirror of https://github.com/postgres/postgres.git synced 2025-07-11 10:01:57 +03:00
Code Activity

Change mechanism to set up source targetlist in MERGE

Browse Source 
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Fix outdated, related comments for fix_join_expr also.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
This commit is contained in:
Alvaro Herrera
2022-04-12 09:29:39 +02:00
parent a4b57543ac
commit ce4f46fdc8
6 changed files with 80 additions and 27 deletions
Download Patch File Download Diff File Expand all files Collapse all files

7
src/backend/optimizer/plan/setrefs.c
View File

@ -2748,7 +2748,7 @@ search_indexed_tlist_for_sortgroupref(Expr *node,
* relation target lists. Also perform opcode lookup and add
* regclass OIDs to root->glob->relationOids.
*
* This is used in three different scenarios:
* This is used in four different scenarios:
* 1) a normal join clause, where all the Vars in the clause *must* be
* replaced by OUTER_VAR or INNER_VAR references. In this case
* acceptable_rel should be zero so that any failure to match a Var will be
@ -2763,6 +2763,11 @@ search_indexed_tlist_for_sortgroupref(Expr *node,
* to-be-updated relation) alone. Correspondingly inner_itlist is to be
* EXCLUDED elements, outer_itlist = NULL and acceptable_rel the target
* relation.
* 4) MERGE. In this case, references to the source relation are to be
* replaced with INNER_VAR references, leaving Vars of the target
* relation (the to-be-modified relation) alone. So inner_itlist is to be
* the source relation elements, outer_itlist = NULL and acceptable_rel
* the target relation.
*
* 'clauses' is the targetlist or list of join clauses
* 'outer_itlist' is the indexed target list of the outer join relation,