Re: generic plans and "initial" pruning

On Wed, Apr 6, 2022 at 4:20 PM Amit Langote <amitlangote09(at)gmail(dot)com> wrote:
> And here is a version like that that passes make check-world. Maybe
> still a WIP as I think comments could use more editing.
>
> Here's how the new implementation works:
>
> AcquireExecutorLocks() calls ExecutorDoInitialPruning(), which in turn
> iterates over a list of PartitionPruneInfos in a given PlannedStmt
> coming from a CachedPlan. For each PartitionPruneInfo,
> ExecPartitionDoInitialPruning() is called, which sets up
> PartitionPruneState and performs initial pruning steps present in the
> PartitionPruneInfo. The resulting bitmapsets of valid subplans, one
> for each PartitionPruneInfo, are collected in a list and added to a
> result node called PartitionPruneResult. It represents the result of
> performing initial pruning on all PartitionPruneInfos found in a plan.
> A list of PartitionPruneResults is passed along with the PlannedStmt
> to the executor, which is referenced when initializing
> Append/MergeAppend nodes.
>
> PlannedStmt.minLockRelids defined by the planner contains the RT
> indexes of all the entries in the range table minus those of the leaf
> partitions whose subplans are subject to removal due to initial
> pruning. AcquireExecutoLocks() adds back the RT indexes of only those
> leaf partitions whose subplans survive ExecutorDoInitialPruning(). To
> get the leaf partition RT indexes from the PartitionPruneInfo, a new
> rti_map array is added to PartitionedRelPruneInfo.
>
> There's only one patch this time. Patches that added partitioned_rels
> and plan_tree_walker() are no longer necessary.

Here's an updated version. In Particular, I removed
part_prune_results list from PortalData, in favor of anything that
needs to look at the list can instead get it from the CachedPlan
(PortalData.cplan). This makes things better in 2 ways:

* All the changes that were needed to produce the list to be pass to
PortalDefineQuery() are now unnecessary (especially ugly ones were
those made to pg_plan_queries()'s interface)

* The cases in which the PartitionPruneResult being added to a
QueryDesc can be assumed to be valid is more clearly define now; it's
the cases where the portal's CachedPlan is also valid, that is, if the
accompanying PlannedStmt is a cached one.

--
Amit Langote
EDB: http://www.enterprisedb.com