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Fix rescanning of async-aware Append nodes.

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In cases where run-time pruning isn't required, the synchronous and
asynchronous subplans for an async-aware Append node determined using
classify_matching_subplans() should be re-used when rescanning the node,
but the previous code re-determined them using that function repeatedly
each time when rescanning the node, leading to incorrect results in a
normal build and an Assert failure in an Assert-enabled build as that
function doesn't assume that it's called repeatedly in such cases.  Fix
the code as mentioned above.

My oversight in commit 27e1f1456.

While at it, initialize async-related pointers/variables to NULL/zero
explicitly in ExecInitAppend() and ExecReScanAppend(), just to be sure.
(The variables would have been set to zero before we get to the latter
function, but let's do so.)

Reviewed-by: Kyotaro Horiguchi
Discussion: https://postgr.es/m/CAPmGK16Q4B2_KY%2BJH7rb7wQbw54AUprp7TMekGTd2T1B62yysQ%40mail.gmail.com
This commit is contained in:
Etsuro Fujita
2021-06-07 12:45:00 +09:00
parent a65e9f3f14
commit f3baaf28a6
3 changed files with 76 additions and 5 deletions
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27
src/backend/executor/nodeAppend.c
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@ -240,10 +240,12 @@ ExecInitAppend(Append *node, EState *estate, int eflags)
appendstate->as_asyncplans = asyncplans;
appendstate->as_nasyncplans = nasyncplans;
appendstate->as_asyncrequests = NULL;
appendstate->as_asyncresults = (TupleTableSlot **)
palloc0(nasyncplans * sizeof(TupleTableSlot *));
appendstate->as_asyncresults = NULL;
appendstate->as_nasyncresults = 0;
appendstate->as_nasyncremain = 0;
appendstate->as_needrequest = NULL;
appendstate->as_eventset = NULL;
appendstate->as_valid_asyncplans = NULL;
if (nasyncplans > 0)
{
@ -265,6 +267,12 @@ ExecInitAppend(Append *node, EState *estate, int eflags)
appendstate->as_asyncrequests[i] = areq;
}
appendstate->as_asyncresults = (TupleTableSlot **)
palloc0(nasyncplans * sizeof(TupleTableSlot *));
if (appendstate->as_valid_subplans != NULL)
classify_matching_subplans(appendstate);
}
/*
@ -459,6 +467,8 @@ ExecReScanAppend(AppendState *node)
areq->result = NULL;
}
node->as_nasyncresults = 0;
node->as_nasyncremain = 0;
bms_free(node->as_needrequest);
node->as_needrequest = NULL;
}
@ -861,15 +871,24 @@ ExecAppendAsyncBegin(AppendState *node)
/* Backward scan is not supported by async-aware Appends. */
Assert(ScanDirectionIsForward(node->ps.state->es_direction));
/* We should never be called when there are no subplans */
Assert(node->as_nplans > 0);
/* We should never be called when there are no async subplans. */
Assert(node->as_nasyncplans > 0);
/* If we've yet to determine the valid subplans then do so now. */
if (node->as_valid_subplans == NULL)
{
node->as_valid_subplans =
ExecFindMatchingSubPlans(node->as_prune_state);
classify_matching_subplans(node);
classify_matching_subplans(node);
}
/* Initialize state variables. */
node->as_syncdone = bms_is_empty(node->as_valid_subplans);
node->as_nasyncremain = bms_num_members(node->as_valid_asyncplans);
/* Nothing to do if there are no valid async subplans. */
if (node->as_nasyncremain == 0)
@ -1148,9 +1167,7 @@ classify_matching_subplans(AppendState *node)
/* Adjust the valid subplans to contain sync subplans only. */
node->as_valid_subplans = bms_del_members(node->as_valid_subplans,
valid_asyncplans);
node->as_syncdone = bms_is_empty(node->as_valid_subplans);
/* Save valid async subplans. */
node->as_valid_asyncplans = valid_asyncplans;
node->as_nasyncremain = bms_num_members(valid_asyncplans);
}