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Improve run-time partition pruning to handle any stable expression.

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The initial coding of the run-time-pruning feature only coped with cases
where the partition key(s) are compared to Params.  That is a bit silly;
we can allow it to work with any non-Var-containing stable expression, as
long as we take special care with expressions containing PARAM_EXEC Params.
The code is hardly any longer this way, and it's considerably clearer
(IMO at least).  Per gripe from Pavel Stehule.

David Rowley, whacked around a bit by me

Discussion: https://postgr.es/m/CAFj8pRBjrufA3ocDm8o4LPGNye9Y+pm1b9kCwode4X04CULG3g@mail.gmail.com
This commit is contained in:
Tom Lane
2018-06-10 15:22:25 -04:00
parent c83e202990
commit 73b7f48f78
11 changed files with 461 additions and 271 deletions
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53
src/backend/executor/nodeAppend.c
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@ -133,29 +133,27 @@ ExecInitAppend(Append *node, EState *estate, int eflags)
{
PartitionPruneState *prunestate;
/* We may need an expression context to evaluate partition exprs */
ExecAssignExprContext(estate, &appendstate->ps);
prunestate = ExecSetupPartitionPruneState(&appendstate->ps,
node->part_prune_infos);
/*
* When there are external params matching the partition key we may be
* able to prune away Append subplans now.
*/
if (!bms_is_empty(prunestate->extparams))
/* Perform an initial partition prune, if required. */
if (prunestate->do_initial_prune)
{
/* Determine which subplans match the external params */
/* Determine which subplans survive initial pruning */
validsubplans = ExecFindInitialMatchingSubPlans(prunestate,
list_length(node->appendplans));
/*
* If no subplans match the given parameters then we must handle
* this case in a special way. The problem here is that code in
* explain.c requires an Append to have at least one subplan in
* order for it to properly determine the Vars in that subplan's
* targetlist. We sidestep this issue by just initializing the
* first subplan and setting as_whichplan to NO_MATCHING_SUBPLANS
* to indicate that we don't need to scan any subnodes.
* The case where no subplans survive pruning must be handled
* specially. The problem here is that code in explain.c requires
* an Append to have at least one subplan in order for it to
* properly determine the Vars in that subplan's targetlist. We
* sidestep this issue by just initializing the first subplan and
* setting as_whichplan to NO_MATCHING_SUBPLANS to indicate that
* we don't really need to scan any subnodes.
*/
if (bms_is_empty(validsubplans))
{
@ -175,14 +173,13 @@ ExecInitAppend(Append *node, EState *estate, int eflags)
}
/*
* If there's no exec params then no further pruning can be done, we
* can just set the valid subplans to all remaining subplans.
* If no runtime pruning is required, we can fill as_valid_subplans
* immediately, preventing later calls to ExecFindMatchingSubPlans.
*/
if (bms_is_empty(prunestate->execparams))
if (!prunestate->do_exec_prune)
appendstate->as_valid_subplans = bms_add_range(NULL, 0, nplans - 1);
appendstate->as_prune_state = prunestate;
}
else
{
@ -190,7 +187,7 @@ ExecInitAppend(Append *node, EState *estate, int eflags)
/*
* When run-time partition pruning is not enabled we can just mark all
* subplans as valid, they must also all be initialized.
* subplans as valid; they must also all be initialized.
*/
appendstate->as_valid_subplans = validsubplans =
bms_add_range(NULL, 0, nplans - 1);
@ -341,13 +338,13 @@ ExecReScanAppend(AppendState *node)
int i;
/*
* If any of the parameters being used for partition pruning have changed,
* then we'd better unset the valid subplans so that they are reselected
* for the new parameter values.
* If any PARAM_EXEC Params used in pruning expressions have changed, then
* we'd better unset the valid subplans so that they are reselected for
* the new parameter values.
*/
if (node->as_prune_state &&
bms_overlap(node->ps.chgParam,
node->as_prune_state->execparams))
node->as_prune_state->execparamids))
{
bms_free(node->as_valid_subplans);
node->as_valid_subplans = NULL;
@ -531,9 +528,9 @@ choose_next_subplan_for_leader(AppendState *node)
node->as_whichplan = node->as_nplans - 1;
/*
* If we've yet to determine the valid subplans for these parameters
* then do so now. If run-time pruning is disabled then the valid
* subplans will always be set to all subplans.
* If we've yet to determine the valid subplans then do so now. If
* run-time pruning is disabled then the valid subplans will always be
* set to all subplans.
*/
if (node->as_valid_subplans == NULL)
{
@ -606,9 +603,9 @@ choose_next_subplan_for_worker(AppendState *node)
node->as_pstate->pa_finished[node->as_whichplan] = true;
/*
* If we've yet to determine the valid subplans for these parameters then
* do so now. If run-time pruning is disabled then the valid subplans
* will always be set to all subplans.
* If we've yet to determine the valid subplans then do so now. If
* run-time pruning is disabled then the valid subplans will always be set
* to all subplans.
*/
else if (node->as_valid_subplans == NULL)
{