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First phase of plan-invalidation project: create a plan cache management

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module and teach PREPARE and protocol-level prepared statements to use it.
In service of this, rearrange utility-statement processing so that parse
analysis does not assume table schemas can't change before execution for
utility statements (necessary because we don't attempt to re-acquire locks
for utility statements when reusing a stored plan).  This requires some
refactoring of the ProcessUtility API, but it ends up cleaner anyway,
for instance we can get rid of the QueryContext global.

Still to do: fix up SPI and related code to use the plan cache; I'm tempted to
try to make SQL functions use it too.  Also, there are at least some aspects
of system state that we want to ensure remain the same during a replan as in
the original processing; search_path certainly ought to behave that way for
instance, and perhaps there are others.
This commit is contained in:
Tom Lane
2007-03-13 00:33:44 +00:00
parent f84308f195
commit b9527e9840
61 changed files with 2478 additions and 1354 deletions
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41
src/include/commands/prepare.h
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@@ -6,7 +6,7 @@
*
* Copyright (c) 2002-2007, PostgreSQL Global Development Group
*
* $PostgreSQL: pgsql/src/include/commands/prepare.h,v 1.24 2007/02/20 17:32:17 tgl Exp $
* $PostgreSQL: pgsql/src/include/commands/prepare.h,v 1.25 2007/03/13 00:33:43 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@@ -14,58 +14,49 @@
#define PREPARE_H
#include "executor/executor.h"
#include "utils/plancache.h"
#include "utils/timestamp.h"
/*
* The data structure representing a prepared statement
* The data structure representing a prepared statement. This is now just
* a thin veneer over a plancache entry --- the main addition is that of
* a name.
*
* A prepared statement might be fully planned, or only parsed-and-rewritten.
* If fully planned, stmt_list contains PlannedStmts and/or utility statements;
* if not, it contains Query nodes.
*
* Note: all subsidiary storage lives in the context denoted by the context
* field. However, the string referenced by commandTag is not subsidiary
* storage; it is assumed to be a compile-time-constant string. As with
* portals, commandTag shall be NULL if and only if the original query string
* (before rewriting) was an empty string.
* Note: all subsidiary storage lives in the referenced plancache entry.
*/
typedef struct
{
/* dynahash.c requires key to be first field */
char stmt_name[NAMEDATALEN];
char *query_string; /* text of query, or NULL */
const char *commandTag; /* command tag (a constant!), or NULL */
List *stmt_list; /* list of statement or Query nodes */
List *argtype_list; /* list of parameter type OIDs */
bool fully_planned; /* what is in stmt_list, exactly? */
CachedPlanSource *plansource; /* the actual cached plan */
bool from_sql; /* prepared via SQL, not FE/BE protocol? */
TimestampTz prepare_time; /* the time when the stmt was prepared */
MemoryContext context; /* context containing this query */
} PreparedStatement;
/* Utility statements PREPARE, EXECUTE, DEALLOCATE, EXPLAIN EXECUTE */
extern void PrepareQuery(PrepareStmt *stmt);
extern void ExecuteQuery(ExecuteStmt *stmt, ParamListInfo params,
extern void PrepareQuery(PrepareStmt *stmt, const char *queryString);
extern void ExecuteQuery(ExecuteStmt *stmt, const char *queryString,
ParamListInfo params,
DestReceiver *dest, char *completionTag);
extern void DeallocateQuery(DeallocateStmt *stmt);
extern void ExplainExecuteQuery(ExplainStmt *stmt, ParamListInfo params,
TupOutputState *tstate);
extern void ExplainExecuteQuery(ExecuteStmt *execstmt, ExplainStmt *stmt,
const char *queryString,
ParamListInfo params, TupOutputState *tstate);
/* Low-level access to stored prepared statements */
extern void StorePreparedStatement(const char *stmt_name,
Node *raw_parse_tree,
const char *query_string,
const char *commandTag,
Oid *param_types,
int num_params,
List *stmt_list,
List *argtype_list,
bool fully_planned,
bool from_sql);
extern PreparedStatement *FetchPreparedStatement(const char *stmt_name,
bool throwError);
extern void DropPreparedStatement(const char *stmt_name, bool showError);
extern List *FetchPreparedStatementParams(const char *stmt_name);
extern TupleDesc FetchPreparedStatementResultDesc(PreparedStatement *stmt);
extern bool PreparedStatementReturnsTuples(PreparedStatement *stmt);
extern List *FetchPreparedStatementTargetList(PreparedStatement *stmt);
#endif /* PREPARE_H */