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28b0478755
Clauses in the lists retained by postgres_fdw during planning were sometimes bare boolean clauses, sometimes RestrictInfos, and sometimes a mixture of the two in the same list. The comment about that situation didn't come close to telling the full truth, either. Aside from being confusing, this had a couple of bad practical consequences: * waste of planning cycles due to inability to cache per-clause selectivity and cost estimates; * sometimes, RestrictInfos would sneak into the fdw_private list of a finished Plan node, causing failures if, for example, we tried to ship the Plan tree to a parallel worker. (It may well be that it's a bug in the parallel-query logic that we would ever try to ship such a plan to a parallel worker, but in any case this deserves to be cleaned up.) To fix, rearrange so that clause lists in PgFdwRelationInfo are always lists of RestrictInfos, and then strip the RestrictInfos at the last minute when making a Plan node. In passing do a bit of refactoring and comment cleanup in postgresGetForeignPlan and foreign_join_ok. Although the messiness here dates back at least to 9.6, there's no evidence that it causes anything worse than wasted planning cycles in 9.6, so no back-patch for now. Per fuzz testing by Andreas Seltenreich. Tom Lane and Ashutosh Bapat Discussion: https://postgr.es/m/87tw5x4vcu.fsf@credativ.de
179 lines
5.7 KiB
C
179 lines
5.7 KiB
C
/*-------------------------------------------------------------------------
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*
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* postgres_fdw.h
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* Foreign-data wrapper for remote PostgreSQL servers
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*
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* Portions Copyright (c) 2012-2017, PostgreSQL Global Development Group
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*
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* IDENTIFICATION
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* contrib/postgres_fdw/postgres_fdw.h
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*
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*-------------------------------------------------------------------------
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*/
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#ifndef POSTGRES_FDW_H
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#define POSTGRES_FDW_H
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#include "foreign/foreign.h"
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#include "lib/stringinfo.h"
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#include "nodes/relation.h"
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#include "utils/relcache.h"
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#include "libpq-fe.h"
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/*
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* FDW-specific planner information kept in RelOptInfo.fdw_private for a
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* foreign table. This information is collected by postgresGetForeignRelSize.
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*/
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typedef struct PgFdwRelationInfo
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{
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/*
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* True means that the relation can be pushed down. Always true for simple
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* foreign scan.
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*/
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bool pushdown_safe;
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/*
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* Restriction clauses, divided into safe and unsafe to pushdown subsets.
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* All entries in these lists should have RestrictInfo wrappers; that
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* improves efficiency of selectivity and cost estimation.
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*/
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List *remote_conds;
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List *local_conds;
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/* Bitmap of attr numbers we need to fetch from the remote server. */
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Bitmapset *attrs_used;
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/* Cost and selectivity of local_conds. */
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QualCost local_conds_cost;
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Selectivity local_conds_sel;
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/* Selectivity of join conditions */
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Selectivity joinclause_sel;
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/* Estimated size and cost for a scan or join. */
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double rows;
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int width;
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Cost startup_cost;
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Cost total_cost;
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/* Costs excluding costs for transferring data from the foreign server */
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Cost rel_startup_cost;
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Cost rel_total_cost;
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/* Options extracted from catalogs. */
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bool use_remote_estimate;
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Cost fdw_startup_cost;
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Cost fdw_tuple_cost;
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List *shippable_extensions; /* OIDs of whitelisted extensions */
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/* Cached catalog information. */
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ForeignTable *table;
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ForeignServer *server;
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UserMapping *user; /* only set in use_remote_estimate mode */
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int fetch_size; /* fetch size for this remote table */
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/*
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* Name of the relation while EXPLAINing ForeignScan. It is used for join
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* relations but is set for all relations. For join relation, the name
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* indicates which foreign tables are being joined and the join type used.
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*/
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StringInfo relation_name;
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/* Join information */
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RelOptInfo *outerrel;
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RelOptInfo *innerrel;
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JoinType jointype;
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List *joinclauses; /* List of RestrictInfo */
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/* Grouping information */
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List *grouped_tlist;
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/* Subquery information */
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bool make_outerrel_subquery; /* do we deparse outerrel as a
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* subquery? */
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bool make_innerrel_subquery; /* do we deparse innerrel as a
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* subquery? */
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Relids lower_subquery_rels; /* all relids appearing in lower
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* subqueries */
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/*
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* Index of the relation. It is used to create an alias to a subquery
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* representing the relation.
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*/
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int relation_index;
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} PgFdwRelationInfo;
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/* in postgres_fdw.c */
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extern int set_transmission_modes(void);
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extern void reset_transmission_modes(int nestlevel);
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/* in connection.c */
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extern PGconn *GetConnection(UserMapping *user, bool will_prep_stmt);
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extern void ReleaseConnection(PGconn *conn);
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extern unsigned int GetCursorNumber(PGconn *conn);
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extern unsigned int GetPrepStmtNumber(PGconn *conn);
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extern PGresult *pgfdw_get_result(PGconn *conn, const char *query);
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extern PGresult *pgfdw_exec_query(PGconn *conn, const char *query);
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extern void pgfdw_report_error(int elevel, PGresult *res, PGconn *conn,
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bool clear, const char *sql);
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/* in option.c */
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extern int ExtractConnectionOptions(List *defelems,
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const char **keywords,
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const char **values);
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extern List *ExtractExtensionList(const char *extensionsString,
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bool warnOnMissing);
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/* in deparse.c */
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extern void classifyConditions(PlannerInfo *root,
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RelOptInfo *baserel,
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List *input_conds,
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List **remote_conds,
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List **local_conds);
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extern bool is_foreign_expr(PlannerInfo *root,
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RelOptInfo *baserel,
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Expr *expr);
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extern void deparseInsertSql(StringInfo buf, PlannerInfo *root,
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Index rtindex, Relation rel,
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List *targetAttrs, bool doNothing, List *returningList,
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List **retrieved_attrs);
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extern void deparseUpdateSql(StringInfo buf, PlannerInfo *root,
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Index rtindex, Relation rel,
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List *targetAttrs, List *returningList,
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List **retrieved_attrs);
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extern void deparseDirectUpdateSql(StringInfo buf, PlannerInfo *root,
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Index rtindex, Relation rel,
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List *targetlist,
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List *targetAttrs,
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List *remote_conds,
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List **params_list,
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List *returningList,
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List **retrieved_attrs);
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extern void deparseDeleteSql(StringInfo buf, PlannerInfo *root,
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Index rtindex, Relation rel,
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List *returningList,
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List **retrieved_attrs);
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extern void deparseDirectDeleteSql(StringInfo buf, PlannerInfo *root,
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Index rtindex, Relation rel,
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List *remote_conds,
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List **params_list,
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List *returningList,
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List **retrieved_attrs);
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extern void deparseAnalyzeSizeSql(StringInfo buf, Relation rel);
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extern void deparseAnalyzeSql(StringInfo buf, Relation rel,
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List **retrieved_attrs);
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extern void deparseStringLiteral(StringInfo buf, const char *val);
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extern Expr *find_em_expr_for_rel(EquivalenceClass *ec, RelOptInfo *rel);
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extern List *build_tlist_to_deparse(RelOptInfo *foreignrel);
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extern void deparseSelectStmtForRel(StringInfo buf, PlannerInfo *root,
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RelOptInfo *foreignrel, List *tlist,
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List *remote_conds, List *pathkeys, bool is_subquery,
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List **retrieved_attrs, List **params_list);
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/* in shippable.c */
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extern bool is_builtin(Oid objectId);
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extern bool is_shippable(Oid objectId, Oid classId, PgFdwRelationInfo *fpinfo);
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extern const char *get_jointype_name(JoinType jointype);
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#endif /* POSTGRES_FDW_H */
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