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Previously, gen_partprune_steps() always built executor pruning steps using all suitable clauses, including those containing PARAM_EXEC Params. This meant that the pruning steps were only completely safe for executor run-time (scan start) pruning. To prune at executor startup, we had to ignore the steps involving exec Params. But this doesn't really work in general, since there may be logic changes needed as well --- for example, pruning according to the last operator's btree strategy is the wrong thing if we're not applying that operator. The rules embodied in gen_partprune_steps() and its minions are sufficiently complicated that tracking their incremental effects in other logic seems quite impractical. Short of a complete redesign, the only safe fix seems to be to run gen_partprune_steps() twice, once to create executor startup pruning steps and then again for run-time pruning steps. We can save a few cycles however by noting during the first scan whether we rejected any clauses because they involved exec Params --- if not, we don't need to do the second scan. In support of this, refactor the internal APIs in partprune.c to make more use of passing information in the GeneratePruningStepsContext struct, rather than as separate arguments. This is, I hope, the last piece of our response to a bug report from Alan Jackson. Back-patch to v11 where this code came in. Discussion: https://postgr.es/m/FAD28A83-AC73-489E-A058-2681FA31D648@tvsquared.com
157 lines
5.9 KiB
C
157 lines
5.9 KiB
C
/*--------------------------------------------------------------------
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* execPartition.h
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* POSTGRES partitioning executor interface
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*
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* Portions Copyright (c) 1996-2019, PostgreSQL Global Development Group
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* Portions Copyright (c) 1994, Regents of the University of California
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*
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* IDENTIFICATION
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* src/include/executor/execPartition.h
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*--------------------------------------------------------------------
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*/
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#ifndef EXECPARTITION_H
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#define EXECPARTITION_H
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#include "nodes/execnodes.h"
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#include "nodes/parsenodes.h"
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#include "nodes/plannodes.h"
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#include "partitioning/partprune.h"
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/* See execPartition.c for the definitions. */
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typedef struct PartitionDispatchData *PartitionDispatch;
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typedef struct PartitionTupleRouting PartitionTupleRouting;
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/*
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* PartitionRoutingInfo
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*
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* Additional result relation information specific to routing tuples to a
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* table partition.
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*/
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typedef struct PartitionRoutingInfo
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{
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/*
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* Map for converting tuples in root partitioned table format into
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* partition format, or NULL if no conversion is required.
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*/
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TupleConversionMap *pi_RootToPartitionMap;
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/*
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* Map for converting tuples in partition format into the root partitioned
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* table format, or NULL if no conversion is required.
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*/
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TupleConversionMap *pi_PartitionToRootMap;
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/*
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* Slot to store tuples in partition format, or NULL when no translation
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* is required between root and partition.
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*/
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TupleTableSlot *pi_PartitionTupleSlot;
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} PartitionRoutingInfo;
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/*
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* PartitionedRelPruningData - Per-partitioned-table data for run-time pruning
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* of partitions. For a multilevel partitioned table, we have one of these
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* for the topmost partition plus one for each non-leaf child partition.
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*
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* subplan_map[] and subpart_map[] have the same definitions as in
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* PartitionedRelPruneInfo (see plannodes.h); though note that here,
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* subpart_map contains indexes into PartitionPruningData.partrelprunedata[].
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*
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* nparts Length of subplan_map[] and subpart_map[].
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* subplan_map Subplan index by partition index, or -1.
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* subpart_map Subpart index by partition index, or -1.
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* present_parts A Bitmapset of the partition indexes that we
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* have subplans or subparts for.
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* initial_pruning_steps List of PartitionPruneSteps used to
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* perform executor startup pruning.
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* exec_pruning_steps List of PartitionPruneSteps used to
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* perform per-scan pruning.
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* initial_context If initial_pruning_steps isn't NIL, contains
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* the details needed to execute those steps.
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* exec_context If exec_pruning_steps isn't NIL, contains
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* the details needed to execute those steps.
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*/
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typedef struct PartitionedRelPruningData
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{
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int nparts;
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int *subplan_map;
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int *subpart_map;
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Bitmapset *present_parts;
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List *initial_pruning_steps;
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List *exec_pruning_steps;
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PartitionPruneContext initial_context;
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PartitionPruneContext exec_context;
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} PartitionedRelPruningData;
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/*
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* PartitionPruningData - Holds all the run-time pruning information for
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* a single partitioning hierarchy containing one or more partitions.
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* partrelprunedata[] is an array ordered such that parents appear before
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* their children; in particular, the first entry is the topmost partition,
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* which was actually named in the SQL query.
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*/
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typedef struct PartitionPruningData
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{
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int num_partrelprunedata; /* number of array entries */
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PartitionedRelPruningData partrelprunedata[FLEXIBLE_ARRAY_MEMBER];
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} PartitionPruningData;
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/*
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* PartitionPruneState - State object required for plan nodes to perform
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* run-time partition pruning.
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*
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* This struct can be attached to plan types which support arbitrary Lists of
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* subplans containing partitions, to allow subplans to be eliminated due to
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* the clauses being unable to match to any tuple that the subplan could
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* possibly produce.
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*
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* execparamids Contains paramids of PARAM_EXEC Params found within
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* any of the partprunedata structs. Pruning must be
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* done again each time the value of one of these
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* parameters changes.
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* other_subplans Contains indexes of subplans that don't belong to any
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* "partprunedata", e.g UNION ALL children that are not
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* partitioned tables, or a partitioned table that the
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* planner deemed run-time pruning to be useless for.
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* These must not be pruned.
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* prune_context A short-lived memory context in which to execute the
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* partition pruning functions.
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* do_initial_prune true if pruning should be performed during executor
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* startup (at any hierarchy level).
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* do_exec_prune true if pruning should be performed during
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* executor run (at any hierarchy level).
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* num_partprunedata Number of items in "partprunedata" array.
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* partprunedata Array of PartitionPruningData pointers for the plan's
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* partitioned relation(s), one for each partitioning
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* hierarchy that requires run-time pruning.
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*/
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typedef struct PartitionPruneState
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{
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Bitmapset *execparamids;
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Bitmapset *other_subplans;
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MemoryContext prune_context;
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bool do_initial_prune;
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bool do_exec_prune;
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int num_partprunedata;
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PartitionPruningData *partprunedata[FLEXIBLE_ARRAY_MEMBER];
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} PartitionPruneState;
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extern PartitionTupleRouting *ExecSetupPartitionTupleRouting(EState *estate,
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ModifyTableState *mtstate,
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Relation rel);
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extern ResultRelInfo *ExecFindPartition(ModifyTableState *mtstate,
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ResultRelInfo *rootResultRelInfo,
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PartitionTupleRouting *proute,
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TupleTableSlot *slot,
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EState *estate);
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extern void ExecCleanupTupleRouting(ModifyTableState *mtstate,
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PartitionTupleRouting *proute);
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extern PartitionPruneState *ExecCreatePartitionPruneState(PlanState *planstate,
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PartitionPruneInfo *partitionpruneinfo);
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extern Bitmapset *ExecFindMatchingSubPlans(PartitionPruneState *prunestate);
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extern Bitmapset *ExecFindInitialMatchingSubPlans(PartitionPruneState *prunestate,
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int nsubplans);
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#endif /* EXECPARTITION_H */
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