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d3c5f37dd5
This replaces dblink's blocking libpq calls, allowing cancellation and allowing DROP DATABASE (of a database not involved in the query). Apart from explicit dblink_cancel_query() calls, dblink still doesn't cancel the remote side. The replacement for the blocking calls consists of new, general-purpose query execution wrappers in the libpqsrv facility. Out-of-tree extensions should adopt these. Use them in postgres_fdw, replacing a local implementation from which the libpqsrv implementation derives. This is a bug fix for dblink. Code inspection identified the bug at least thirteen years ago, but user complaints have not appeared. Hence, no back-patch for now. Discussion: https://postgr.es/m/20231122012945.74@rfd.leadboat.com
260 lines
8.7 KiB
C
260 lines
8.7 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) 2012-2024, 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 "libpq-fe.h"
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#include "nodes/execnodes.h"
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#include "nodes/pathnodes.h"
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#include "utils/relcache.h"
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/*
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* FDW-specific planner information kept in RelOptInfo.fdw_private for a
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* postgres_fdw foreign table. For a baserel, this struct is created by
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* postgresGetForeignRelSize, although some fields are not filled till later.
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* postgresGetForeignJoinPaths creates it for a joinrel, and
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* postgresGetForeignUpperPaths creates it for an upperrel.
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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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/* Actual remote restriction clauses for scan (sans RestrictInfos) */
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List *final_remote_exprs;
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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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/* True means that the query_pathkeys is safe to push down */
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bool qp_is_pushdown_safe;
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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, join, or grouping/aggregation. */
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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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/*
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* Estimated number of rows fetched from the foreign server, and costs
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* excluding costs for transferring those rows from the foreign server.
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* These are only used by estimate_path_cost_size().
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*/
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double retrieved_rows;
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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 shippable extensions */
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bool async_capable;
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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, for use while EXPLAINing ForeignScan. It is used
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* for join and upper relations but is set for all relations. For a base
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* relation, this is really just the RT index as a string; we convert that
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* while producing EXPLAIN output. For join and upper relations, the name
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* indicates which base foreign tables are included and the join type or
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* aggregation type used.
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*/
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char *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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/* joinclauses contains only JOIN/ON conditions for an outer join */
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List *joinclauses; /* List of RestrictInfo */
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/* Upper relation information */
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UpperRelationKind stage;
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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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Relids hidden_subquery_rels; /* relids, which can't be referred to
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* from upper relations, used
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* internally for equivalence member
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* search */
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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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/*
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* Extra control information relating to a connection.
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*/
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typedef struct PgFdwConnState
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{
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AsyncRequest *pendingAreq; /* pending async request */
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} PgFdwConnState;
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/*
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* Method used by ANALYZE to sample remote rows.
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*/
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typedef enum PgFdwSamplingMethod
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{
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ANALYZE_SAMPLE_OFF, /* no remote sampling */
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ANALYZE_SAMPLE_AUTO, /* choose by server version */
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ANALYZE_SAMPLE_RANDOM, /* remote random() */
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ANALYZE_SAMPLE_SYSTEM, /* TABLESAMPLE system */
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ANALYZE_SAMPLE_BERNOULLI, /* TABLESAMPLE bernoulli */
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} PgFdwSamplingMethod;
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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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extern void process_pending_request(AsyncRequest *areq);
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/* in connection.c */
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extern PGconn *GetConnection(UserMapping *user, bool will_prep_stmt,
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PgFdwConnState **state);
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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 void do_sql_command(PGconn *conn, const char *sql);
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extern PGresult *pgfdw_get_result(PGconn *conn);
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extern PGresult *pgfdw_exec_query(PGconn *conn, const char *query,
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PgFdwConnState *state);
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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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extern char *process_pgfdw_appname(const char *appname);
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extern char *pgfdw_application_name;
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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 bool is_foreign_param(PlannerInfo *root,
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RelOptInfo *baserel,
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Expr *expr);
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extern bool is_foreign_pathkey(PlannerInfo *root,
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RelOptInfo *baserel,
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PathKey *pathkey);
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extern void deparseInsertSql(StringInfo buf, RangeTblEntry *rte,
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Index rtindex, Relation rel,
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List *targetAttrs, bool doNothing,
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List *withCheckOptionList, List *returningList,
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List **retrieved_attrs, int *values_end_len);
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extern void rebuildInsertSql(StringInfo buf, Relation rel,
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char *orig_query, List *target_attrs,
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int values_end_len, int num_params,
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int num_rows);
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extern void deparseUpdateSql(StringInfo buf, RangeTblEntry *rte,
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Index rtindex, Relation rel,
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List *targetAttrs,
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List *withCheckOptionList, 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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RelOptInfo *foreignrel,
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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, RangeTblEntry *rte,
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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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RelOptInfo *foreignrel,
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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 deparseAnalyzeInfoSql(StringInfo buf, Relation rel);
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extern void deparseAnalyzeSql(StringInfo buf, Relation rel,
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PgFdwSamplingMethod sample_method,
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double sample_frac,
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List **retrieved_attrs);
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extern void deparseTruncateSql(StringInfo buf,
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List *rels,
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DropBehavior behavior,
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bool restart_seqs);
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extern void deparseStringLiteral(StringInfo buf, const char *val);
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extern EquivalenceMember *find_em_for_rel(PlannerInfo *root,
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EquivalenceClass *ec,
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RelOptInfo *rel);
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extern EquivalenceMember *find_em_for_rel_target(PlannerInfo *root,
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EquivalenceClass *ec,
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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 *rel, List *tlist,
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List *remote_conds, List *pathkeys,
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bool has_final_sort, bool has_limit,
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bool is_subquery,
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List **retrieved_attrs, List **params_list);
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extern const char *get_jointype_name(JoinType jointype);
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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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#endif /* POSTGRES_FDW_H */
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