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Make simpler-simple-expressions code cope with a Gather plan. 

Commit 00418c612 expected that the plan generated for a simple-expression
query would always be a plain Result node.  However, if force_parallel_mode
is on, the planner might stick a Gather atop that.  Cope by looking through
the Gather.  For safety, assert that the Gather's tlist is trivial.

Per buildfarm.

Discussion: https://postgr.es/m/23425.1502822098@sss.pgh.pa.us
This commit is contained in:
Tom Lane 2017-08-15 16:49:47 -04:00
parent 70b573b267
commit b73f1b5c29
1 changed files with 47 additions and 16 deletions
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63
src/pl/plpgsql/src/pl_exec.c
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@ -6553,7 +6553,7 @@ exec_save_simple_expr(PLpgSQL_expr *expr, CachedPlan *cplan)
{
PlannedStmt *stmt;
Plan *plan;
TargetEntry *tle;
Expr *tle_expr;
/*
* Given the checks that exec_simple_check_plan did, none of the Asserts
@ -6563,33 +6563,64 @@ exec_save_simple_expr(PLpgSQL_expr *expr, CachedPlan *cplan)
/* Extract the single PlannedStmt */
Assert(list_length(cplan->stmt_list) == 1);
stmt = linitial_node(PlannedStmt, cplan->stmt_list);
/* Should be a trivial Result plan */
Assert(stmt->commandType == CMD_SELECT);
plan = stmt->planTree;
Assert(IsA(plan, Result));
Assert(plan->lefttree == NULL &&
plan->righttree == NULL &&
plan->initPlan == NULL &&
plan->qual == NULL &&
((Result *) plan)->resconstantqual == NULL);
/* Extract the single tlist expression */
Assert(list_length(plan->targetlist) == 1);
tle = (TargetEntry *) linitial(plan->targetlist);
/*
* Ordinarily, the plan node should be a simple Result. However, if
* force_parallel_mode is on, the planner might've stuck a Gather node
* atop that. The simplest way to deal with this is to look through the
* Gather node. The Gather node's tlist would normally contain a Var
* referencing the child node's output ... but setrefs.c might also have
* copied a Const as-is.
*/
plan = stmt->planTree;
for (;;)
{
/* Extract the single tlist expression */
Assert(list_length(plan->targetlist) == 1);
tle_expr = castNode(TargetEntry, linitial(plan->targetlist))->expr;
if (IsA(plan, Result))
{
Assert(plan->lefttree == NULL &&
plan->righttree == NULL &&
plan->initPlan == NULL &&
plan->qual == NULL &&
((Result *) plan)->resconstantqual == NULL);
break;
}
else if (IsA(plan, Gather))
{
Assert(plan->lefttree != NULL &&
plan->righttree == NULL &&
plan->initPlan == NULL &&
plan->qual == NULL);
/* If setrefs.c copied up a Const, no need to look further */
if (IsA(tle_expr, Const))
break;
/* Otherwise, it better be an outer Var */
Assert(IsA(tle_expr, Var));
Assert(((Var *) tle_expr)->varno == OUTER_VAR);
/* Descend to the child node */
plan = plan->lefttree;
}
else
elog(ERROR, "unexpected plan node type: %d",
(int) nodeTag(plan));
}
/*
* Save the simple expression, and initialize state to "not valid in
* current transaction".
*/
expr->expr_simple_expr = tle->expr;
expr->expr_simple_expr = tle_expr;
expr->expr_simple_generation = cplan->generation;
expr->expr_simple_state = NULL;
expr->expr_simple_in_use = false;
expr->expr_simple_lxid = InvalidLocalTransactionId;
/* Also stash away the expression result type */
expr->expr_simple_type = exprType((Node *) tle->expr);
expr->expr_simple_typmod = exprTypmod((Node *) tle->expr);
expr->expr_simple_type = exprType((Node *) tle_expr);
expr->expr_simple_typmod = exprTypmod((Node *) tle_expr);
}
/*