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Fix several bugs related to ON CONFLICT's EXCLUDED pseudo relation.

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Four related issues:

1) attnos/varnos/resnos for EXCLUDED were out of sync when a column
   after one dropped in the underlying relation was referenced.
2) References to whole-row variables (i.e. EXCLUDED.*) lead to errors.
3) It was possible to reference system columns in the EXCLUDED pseudo
   relations, even though they would not have valid contents.
4) References to EXCLUDED were rewritten by the RLS machinery, as
   EXCLUDED was treated as if it were the underlying relation.

To fix the first two issues, generate the excluded targetlist with
dropped columns in mind and add an entry for whole row
variables. Instead of unconditionally adding a wholerow entry we could
pull up the expression if needed, but doing it unconditionally seems
simpler. The wholerow entry is only really needed for ruleutils/EXPLAIN
support anyway.

The remaining two issues are addressed by changing the EXCLUDED RTE to
have relkind = composite. That fits with EXCLUDED not actually being a
real relation, and allows to treat it differently in the relevant
places. scanRTEForColumn now skips looking up system columns when the
RTE has a composite relkind; fireRIRrules() already had a corresponding
check, thereby preventing RLS expansion on EXCLUDED.

Also add tests for these issues, and improve a few comments around
excluded handling in setrefs.c.

Reported-By: Peter Geoghegan, Geoff Winkless
Author: Andres Freund, Amit Langote, Peter Geoghegan
Discussion: CAEzk6fdzJ3xYQZGbcuYM2rBd2BuDkUksmK=mY9UYYDugg_GgZg@mail.gmail.com,
   CAM3SWZS+CauzbiCEcg-GdE6K6ycHE_Bz6Ksszy8AoixcMHOmsA@mail.gmail.com
Backpatch: 9.5, where ON CONFLICT was introduced
This commit is contained in:
Andres Freund
2015-10-03 15:12:10 +02:00
parent 1023194b7a
commit ad22783792
7 changed files with 283 additions and 38 deletions
Download Patch File Download Diff File Expand all files Collapse all files

29
src/backend/optimizer/plan/setrefs.c
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@ -1935,16 +1935,21 @@ search_indexed_tlist_for_sortgroupref(Node *node,
* relation target lists. Also perform opcode lookup and add
* regclass OIDs to root->glob->relationOids.
*
* This is used in two different scenarios: a normal join clause, where all
* the Vars in the clause *must* be replaced by OUTER_VAR or INNER_VAR
* references; and a RETURNING clause, which may contain both Vars of the
* target relation and Vars of other relations. In the latter case we want
* to replace the other-relation Vars by OUTER_VAR references, while leaving
* target Vars alone.
*
* For a normal join, acceptable_rel should be zero so that any failure to
* match a Var will be reported as an error. For the RETURNING case, pass
* inner_itlist = NULL and acceptable_rel = the ID of the target relation.
* This is used in three 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
* reported as an error.
* 2) RETURNING clauses, which may contain both Vars of the target relation
* and Vars of other relations. In this case we want to replace the
* other-relation Vars by OUTER_VAR references, while leaving target Vars
* alone. Thus inner_itlist = NULL and acceptable_rel = the ID of the
* target relation should be passed.
* 3) ON CONFLICT UPDATE SET/WHERE clauses. Here references to EXCLUDED are
* to be replaced with INNER_VAR references, while leaving target Vars (the
* to-be-updated relation) alone. Correspondingly inner_itlist is to be
* EXCLUDED 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,
@ -1987,7 +1992,7 @@ fix_join_expr_mutator(Node *node, fix_join_expr_context *context)
{
Var *var = (Var *) node;
/* First look for the var in the input tlists */
/* Look for the var in the input tlists, first in the outer */
if (context->outer_itlist)
{
newvar = search_indexed_tlist_for_var(var,
@ -1998,7 +2003,7 @@ fix_join_expr_mutator(Node *node, fix_join_expr_context *context)
return (Node *) newvar;
}
/* Then in the outer */
/* then in the inner. */
if (context->inner_itlist)
{
newvar = search_indexed_tlist_for_var(var,