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Allow FDWs to push down quals without breaking EvalPlanQual rechecks.

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This fixes a long-standing bug which was discovered while investigating
the interaction between the new join pushdown code and the EvalPlanQual
machinery: if a ForeignScan appears on the inner side of a paramaterized
nestloop, an EPQ recheck would re-return the original tuple even if
it no longer satisfied the pushed-down quals due to changed parameter
values.

This fix adds a new member to ForeignScan and ForeignScanState and a
new argument to make_foreignscan, and requires changes to FDWs which
push down quals to populate that new argument with a list of quals they
have chosen to push down.  Therefore, I'm only back-patching to 9.5,
even though the bug is not new in 9.5.

Etsuro Fujita, reviewed by me and by Kyotaro Horiguchi.
This commit is contained in:
Robert Haas
2015-10-15 13:00:40 -04:00
parent 817588bc2b
commit 5fc4c26db5
13 changed files with 71 additions and 13 deletions
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14
contrib/postgres_fdw/postgres_fdw.c
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@ -748,6 +748,7 @@ postgresGetForeignPlan(PlannerInfo *root,
Index scan_relid = baserel->relid;
List *fdw_private;
List *remote_conds = NIL;
List *remote_exprs = NIL;
List *local_exprs = NIL;
List *params_list = NIL;
List *retrieved_attrs;
@ -769,8 +770,8 @@ postgresGetForeignPlan(PlannerInfo *root,
*
* This code must match "extract_actual_clauses(scan_clauses, false)"
* except for the additional decision about remote versus local execution.
* Note however that we only strip the RestrictInfo nodes from the
* local_exprs list, since appendWhereClause expects a list of
* Note however that we don't strip the RestrictInfo nodes from the
* remote_conds list, since appendWhereClause expects a list of
* RestrictInfos.
*/
foreach(lc, scan_clauses)
@ -784,11 +785,17 @@ postgresGetForeignPlan(PlannerInfo *root,
continue;
if (list_member_ptr(fpinfo->remote_conds, rinfo))
{
remote_conds = lappend(remote_conds, rinfo);
remote_exprs = lappend(remote_exprs, rinfo->clause);
}
else if (list_member_ptr(fpinfo->local_conds, rinfo))
local_exprs = lappend(local_exprs, rinfo->clause);
else if (is_foreign_expr(root, baserel, rinfo->clause))
{
remote_conds = lappend(remote_conds, rinfo);
remote_exprs = lappend(remote_exprs, rinfo->clause);
}
else
local_exprs = lappend(local_exprs, rinfo->clause);
}
@ -874,7 +881,8 @@ postgresGetForeignPlan(PlannerInfo *root,
scan_relid,
params_list,
fdw_private,
NIL /* no custom tlist */ );
NIL, /* no custom tlist */
remote_exprs);
}
/*