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If a domain has no constraints, then CoerceToDomain doesn't really do anything and can be simplified to a RelabelType. This not only eliminates cycles at execution, but allows the planner to optimize better (for instance, match the coerced expression to an index on the underlying column). However, we do have to support invalidating the plan later if a constraint gets added to the domain. That's comparable to the case of a change to a SQL function that had been inlined into a plan, so all the necessary logic already exists for plans depending on functions. We need only duplicate or share that logic for domains. ALTER DOMAIN ADD/DROP CONSTRAINT need to be taught to send out sinval messages for the domain's pg_type entry, since those operations don't update that row. (ALTER DOMAIN SET/DROP NOT NULL do update that row, so no code change is needed for them.) Testing this revealed what's really a pre-existing bug in plpgsql: it caches the SQL-expression-tree expansion of type coercions and had no provision for invalidating entries in that cache. Up to now that was only a problem if such an expression had inlined a SQL function that got changed, which is unlikely though not impossible. But failing to track changes of domain constraints breaks an existing regression test case and would likely cause practical problems too. We could fix that locally in plpgsql, but what seems like a better idea is to build some generic infrastructure in plancache.c to store standalone expressions and track invalidation events for them. (It's tempting to wonder whether plpgsql's "simple expression" stuff could use this code with lower overhead than its current use of the heavyweight plancache APIs. But I've left that idea for later.) Other stuff fixed in passing: * Allow estimate_expression_value() to drop CoerceToDomain unconditionally, effectively assuming that the coercion will succeed. This will improve planner selectivity estimates for cases involving estimatable expressions that are coerced to domains. We could have done this independently of everything else here, but there wasn't previously any need for eval_const_expressions_mutator to know about CoerceToDomain at all. * Use a dlist for plancache.c's list of cached plans, rather than a manually threaded singly-linked list. That eliminates a potential performance problem in DropCachedPlan. * Fix a couple of inconsistencies in typecmds.c about whether operations on domains drop RowExclusiveLock on pg_type. Our common practice is that DDL operations do drop catalog locks, so standardize on that choice. Discussion: https://postgr.es/m/19958.1544122124@sss.pgh.pa.us
128 lines
4.3 KiB
C
128 lines
4.3 KiB
C
/*-------------------------------------------------------------------------
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*
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* planmain.h
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* prototypes for various files in optimizer/plan
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*
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*
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* Portions Copyright (c) 1996-2018, 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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* src/include/optimizer/planmain.h
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*
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*-------------------------------------------------------------------------
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*/
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#ifndef PLANMAIN_H
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#define PLANMAIN_H
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#include "nodes/plannodes.h"
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#include "nodes/relation.h"
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/* possible values for force_parallel_mode */
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typedef enum
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{
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FORCE_PARALLEL_OFF,
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FORCE_PARALLEL_ON,
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FORCE_PARALLEL_REGRESS
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} ForceParallelMode;
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/* GUC parameters */
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#define DEFAULT_CURSOR_TUPLE_FRACTION 0.1
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extern double cursor_tuple_fraction;
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extern int force_parallel_mode;
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extern bool parallel_leader_participation;
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/* query_planner callback to compute query_pathkeys */
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typedef void (*query_pathkeys_callback) (PlannerInfo *root, void *extra);
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/*
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* prototypes for plan/planmain.c
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*/
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extern RelOptInfo *query_planner(PlannerInfo *root, List *tlist,
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query_pathkeys_callback qp_callback, void *qp_extra);
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/*
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* prototypes for plan/planagg.c
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*/
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extern void preprocess_minmax_aggregates(PlannerInfo *root, List *tlist);
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/*
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* prototypes for plan/createplan.c
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*/
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extern Plan *create_plan(PlannerInfo *root, Path *best_path);
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extern ForeignScan *make_foreignscan(List *qptlist, List *qpqual,
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Index scanrelid, List *fdw_exprs, List *fdw_private,
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List *fdw_scan_tlist, List *fdw_recheck_quals,
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Plan *outer_plan);
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extern Plan *change_plan_targetlist(Plan *subplan, List *tlist,
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bool tlist_parallel_safe);
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extern Plan *materialize_finished_plan(Plan *subplan);
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extern bool is_projection_capable_path(Path *path);
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extern bool is_projection_capable_plan(Plan *plan);
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/* External use of these functions is deprecated: */
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extern Sort *make_sort_from_sortclauses(List *sortcls, Plan *lefttree);
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extern Agg *make_agg(List *tlist, List *qual,
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AggStrategy aggstrategy, AggSplit aggsplit,
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int numGroupCols, AttrNumber *grpColIdx, Oid *grpOperators,
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List *groupingSets, List *chain,
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double dNumGroups, Plan *lefttree);
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extern Limit *make_limit(Plan *lefttree, Node *limitOffset, Node *limitCount);
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/*
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* prototypes for plan/initsplan.c
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*/
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extern int from_collapse_limit;
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extern int join_collapse_limit;
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extern void add_base_rels_to_query(PlannerInfo *root, Node *jtnode);
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extern void build_base_rel_tlists(PlannerInfo *root, List *final_tlist);
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extern void add_vars_to_targetlist(PlannerInfo *root, List *vars,
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Relids where_needed, bool create_new_ph);
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extern void find_lateral_references(PlannerInfo *root);
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extern void create_lateral_join_info(PlannerInfo *root);
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extern List *deconstruct_jointree(PlannerInfo *root);
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extern void distribute_restrictinfo_to_rels(PlannerInfo *root,
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RestrictInfo *restrictinfo);
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extern void process_implied_equality(PlannerInfo *root,
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Oid opno,
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Oid collation,
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Expr *item1,
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Expr *item2,
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Relids qualscope,
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Relids nullable_relids,
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Index security_level,
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bool below_outer_join,
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bool both_const);
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extern RestrictInfo *build_implied_join_equality(Oid opno,
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Oid collation,
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Expr *item1,
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Expr *item2,
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Relids qualscope,
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Relids nullable_relids,
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Index security_level);
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extern void match_foreign_keys_to_quals(PlannerInfo *root);
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/*
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* prototypes for plan/analyzejoins.c
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*/
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extern List *remove_useless_joins(PlannerInfo *root, List *joinlist);
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extern void reduce_unique_semijoins(PlannerInfo *root);
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extern bool query_supports_distinctness(Query *query);
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extern bool query_is_distinct_for(Query *query, List *colnos, List *opids);
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extern bool innerrel_is_unique(PlannerInfo *root,
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Relids joinrelids, Relids outerrelids, RelOptInfo *innerrel,
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JoinType jointype, List *restrictlist, bool force_cache);
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/*
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* prototypes for plan/setrefs.c
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*/
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extern Plan *set_plan_references(PlannerInfo *root, Plan *plan);
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extern void record_plan_function_dependency(PlannerInfo *root, Oid funcid);
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extern void record_plan_type_dependency(PlannerInfo *root, Oid typeid);
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extern void extract_query_dependencies(Node *query,
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List **relationOids,
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List **invalItems,
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bool *hasRowSecurity);
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extern bool extract_query_dependencies_walker(Node *node, PlannerInfo *root);
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#endif /* PLANMAIN_H */
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