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A QueryEnvironment concept is added, which allows new types of objects to be passed into queries from parsing on through execution. At this point, the only thing implemented is a collection of EphemeralNamedRelation objects -- relations which can be referenced by name in queries, but do not exist in the catalogs. The only type of ENR implemented is NamedTuplestore, but provision is made to add more types fairly easily. An ENR can carry its own TupleDesc or reference a relation in the catalogs by relid. Although these features can be used without SPI, convenience functions are added to SPI so that ENRs can easily be used by code run through SPI. The initial use of all this is going to be transition tables in AFTER triggers, but that will be added to each PL as a separate commit. An incidental effect of this patch is to produce a more informative error message if an attempt is made to modify the contents of a CTE from a referencing DML statement. No tests previously covered that possibility, so one is added. Kevin Grittner and Thomas Munro Reviewed by Heikki Linnakangas, David Fetter, and Thomas Munro with valuable comments and suggestions from many others
60 lines
2.1 KiB
C
60 lines
2.1 KiB
C
/*-------------------------------------------------------------------------
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*
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* prepare.h
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* PREPARE, EXECUTE and DEALLOCATE commands, and prepared-stmt storage
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*
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*
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* Copyright (c) 2002-2017, PostgreSQL Global Development Group
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*
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* src/include/commands/prepare.h
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*
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*-------------------------------------------------------------------------
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*/
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#ifndef PREPARE_H
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#define PREPARE_H
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#include "commands/explain.h"
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#include "datatype/timestamp.h"
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#include "utils/plancache.h"
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/*
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* The data structure representing a prepared statement. This is now just
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* a thin veneer over a plancache entry --- the main addition is that of
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* a name.
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*
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* Note: all subsidiary storage lives in the referenced plancache entry.
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*/
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typedef struct
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{
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/* dynahash.c requires key to be first field */
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char stmt_name[NAMEDATALEN];
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CachedPlanSource *plansource; /* the actual cached plan */
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bool from_sql; /* prepared via SQL, not FE/BE protocol? */
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TimestampTz prepare_time; /* the time when the stmt was prepared */
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} PreparedStatement;
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/* Utility statements PREPARE, EXECUTE, DEALLOCATE, EXPLAIN EXECUTE */
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extern void PrepareQuery(PrepareStmt *stmt, const char *queryString,
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int stmt_location, int stmt_len);
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extern void ExecuteQuery(ExecuteStmt *stmt, IntoClause *intoClause,
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const char *queryString, ParamListInfo params,
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DestReceiver *dest, char *completionTag);
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extern void DeallocateQuery(DeallocateStmt *stmt);
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extern void ExplainExecuteQuery(ExecuteStmt *execstmt, IntoClause *into,
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ExplainState *es, const char *queryString,
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ParamListInfo params, QueryEnvironment *queryEnv);
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/* Low-level access to stored prepared statements */
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extern void StorePreparedStatement(const char *stmt_name,
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CachedPlanSource *plansource,
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bool from_sql);
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extern PreparedStatement *FetchPreparedStatement(const char *stmt_name,
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bool throwError);
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extern void DropPreparedStatement(const char *stmt_name, bool showError);
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extern TupleDesc FetchPreparedStatementResultDesc(PreparedStatement *stmt);
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extern List *FetchPreparedStatementTargetList(PreparedStatement *stmt);
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extern void DropAllPreparedStatements(void);
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#endif /* PREPARE_H */
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