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postgresql/src/include/executor/spi.h
Peter Eisentraut 8561e4840c Transaction control in PL procedures 
In each of the supplied procedural languages (PL/pgSQL, PL/Perl,
PL/Python, PL/Tcl), add language-specific commit and rollback
functions/commands to control transactions in procedures in that
language.  Add similar underlying functions to SPI.  Some additional
cleanup so that transaction commit or abort doesn't blow away data
structures still used by the procedure call.  Add execution context
tracking to CALL and DO statements so that transaction control commands
can only be issued in top-level procedure and block calls, not function
calls or other procedure or block calls.

- SPI

Add a new function SPI_connect_ext() that is like SPI_connect() but
allows passing option flags.  The only option flag right now is
SPI_OPT_NONATOMIC.  A nonatomic SPI connection can execute transaction
control commands, otherwise it's not allowed.  This is meant to be
passed down from CALL and DO statements which themselves know in which
context they are called.  A nonatomic SPI connection uses different
memory management.  A normal SPI connection allocates its memory in
TopTransactionContext.  For nonatomic connections we use PortalContext
instead.  As the comment in SPI_connect_ext() (previously SPI_connect())
indicates, one could potentially use PortalContext in all cases, but it
seems safest to leave the existing uses alone, because this stuff is
complicated enough already.

SPI also gets new functions SPI_start_transaction(), SPI_commit(), and
SPI_rollback(), which can be used by PLs to implement their transaction
control logic.

- portalmem.c

Some adjustments were made in the code that cleans up portals at
transaction abort.  The portal code could already handle a command
*committing* a transaction and continuing (e.g., VACUUM), but it was not
quite prepared for a command *aborting* a transaction and continuing.

In AtAbort_Portals(), remove the code that marks an active portal as
failed.  As the comment there already predicted, this doesn't work if
the running command wants to keep running after transaction abort.  And
it's actually not necessary, because pquery.c is careful to run all
portal code in a PG_TRY block and explicitly runs MarkPortalFailed() if
there is an exception.  So the code in AtAbort_Portals() is never used
anyway.

In AtAbort_Portals() and AtCleanup_Portals(), we need to be careful not
to clean up active portals too much.  This mirrors similar code in
PreCommit_Portals().

- PL/Perl

Gets new functions spi_commit() and spi_rollback()

- PL/pgSQL

Gets new commands COMMIT and ROLLBACK.

Update the PL/SQL porting example in the documentation to reflect that
transactions are now possible in procedures.

- PL/Python

Gets new functions plpy.commit and plpy.rollback.

- PL/Tcl

Gets new commands commit and rollback.

Reviewed-by: Andrew Dunstan <andrew.dunstan@2ndquadrant.com>
2018-01-22 08:43:06 -05:00

170 lines
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/*-------------------------------------------------------------------------
*
* spi.h
* Server Programming Interface public declarations
*
* Portions Copyright (c) 1996-2018, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
* src/include/executor/spi.h
*
*-------------------------------------------------------------------------
*/
#ifndef SPI_H
#define SPI_H
#include "commands/trigger.h"
#include "lib/ilist.h"
#include "nodes/parsenodes.h"
#include "utils/portal.h"
typedef struct SPITupleTable
{
MemoryContext tuptabcxt; /* memory context of result table */
uint64 alloced; /* # of alloced vals */
uint64 free; /* # of free vals */
TupleDesc tupdesc; /* tuple descriptor */
HeapTuple *vals; /* tuples */
slist_node next; /* link for internal bookkeeping */
SubTransactionId subid; /* subxact in which tuptable was created */
} SPITupleTable;
/* Plans are opaque structs for standard users of SPI */
typedef struct _SPI_plan *SPIPlanPtr;
#define SPI_ERROR_CONNECT (-1)
#define SPI_ERROR_COPY (-2)
#define SPI_ERROR_OPUNKNOWN (-3)
#define SPI_ERROR_UNCONNECTED (-4)
#define SPI_ERROR_CURSOR (-5) /* not used anymore */
#define SPI_ERROR_ARGUMENT (-6)
#define SPI_ERROR_PARAM (-7)
#define SPI_ERROR_TRANSACTION (-8)
#define SPI_ERROR_NOATTRIBUTE (-9)
#define SPI_ERROR_NOOUTFUNC (-10)
#define SPI_ERROR_TYPUNKNOWN (-11)
#define SPI_ERROR_REL_DUPLICATE (-12)
#define SPI_ERROR_REL_NOT_FOUND (-13)
#define SPI_OK_CONNECT 1
#define SPI_OK_FINISH 2
#define SPI_OK_FETCH 3
#define SPI_OK_UTILITY 4
#define SPI_OK_SELECT 5
#define SPI_OK_SELINTO 6
#define SPI_OK_INSERT 7
#define SPI_OK_DELETE 8
#define SPI_OK_UPDATE 9
#define SPI_OK_CURSOR 10
#define SPI_OK_INSERT_RETURNING 11
#define SPI_OK_DELETE_RETURNING 12
#define SPI_OK_UPDATE_RETURNING 13
#define SPI_OK_REWRITTEN 14
#define SPI_OK_REL_REGISTER 15
#define SPI_OK_REL_UNREGISTER 16
#define SPI_OK_TD_REGISTER 17
#define SPI_OPT_NONATOMIC (1 << 0)
/* These used to be functions, now just no-ops for backwards compatibility */
#define SPI_push() ((void) 0)
#define SPI_pop() ((void) 0)
#define SPI_push_conditional() false
#define SPI_pop_conditional(pushed) ((void) 0)
#define SPI_restore_connection() ((void) 0)
extern PGDLLIMPORT uint64 SPI_processed;
extern PGDLLIMPORT Oid SPI_lastoid;
extern PGDLLIMPORT SPITupleTable *SPI_tuptable;
extern PGDLLIMPORT int SPI_result;
extern int SPI_connect(void);
extern int SPI_connect_ext(int options);
extern int SPI_finish(void);
extern int SPI_execute(const char *src, bool read_only, long tcount);
extern int SPI_execute_plan(SPIPlanPtr plan, Datum *Values, const char *Nulls,
bool read_only, long tcount);
extern int SPI_execute_plan_with_paramlist(SPIPlanPtr plan,
ParamListInfo params,
bool read_only, long tcount);
extern int SPI_exec(const char *src, long tcount);
extern int SPI_execp(SPIPlanPtr plan, Datum *Values, const char *Nulls,
long tcount);
extern int SPI_execute_snapshot(SPIPlanPtr plan,
Datum *Values, const char *Nulls,
Snapshot snapshot,
Snapshot crosscheck_snapshot,
bool read_only, bool fire_triggers, long tcount);
extern int SPI_execute_with_args(const char *src,
int nargs, Oid *argtypes,
Datum *Values, const char *Nulls,
bool read_only, long tcount);
extern SPIPlanPtr SPI_prepare(const char *src, int nargs, Oid *argtypes);
extern SPIPlanPtr SPI_prepare_cursor(const char *src, int nargs, Oid *argtypes,
int cursorOptions);
extern SPIPlanPtr SPI_prepare_params(const char *src,
ParserSetupHook parserSetup,
void *parserSetupArg,
int cursorOptions);
extern int SPI_keepplan(SPIPlanPtr plan);
extern SPIPlanPtr SPI_saveplan(SPIPlanPtr plan);
extern int SPI_freeplan(SPIPlanPtr plan);
extern Oid SPI_getargtypeid(SPIPlanPtr plan, int argIndex);
extern int SPI_getargcount(SPIPlanPtr plan);
extern bool SPI_is_cursor_plan(SPIPlanPtr plan);
extern bool SPI_plan_is_valid(SPIPlanPtr plan);
extern const char *SPI_result_code_string(int code);
extern List *SPI_plan_get_plan_sources(SPIPlanPtr plan);
extern CachedPlan *SPI_plan_get_cached_plan(SPIPlanPtr plan);
extern HeapTuple SPI_copytuple(HeapTuple tuple);
extern HeapTupleHeader SPI_returntuple(HeapTuple tuple, TupleDesc tupdesc);
extern HeapTuple SPI_modifytuple(Relation rel, HeapTuple tuple, int natts,
int *attnum, Datum *Values, const char *Nulls);
extern int SPI_fnumber(TupleDesc tupdesc, const char *fname);
extern char *SPI_fname(TupleDesc tupdesc, int fnumber);
extern char *SPI_getvalue(HeapTuple tuple, TupleDesc tupdesc, int fnumber);
extern Datum SPI_getbinval(HeapTuple tuple, TupleDesc tupdesc, int fnumber, bool *isnull);
extern char *SPI_gettype(TupleDesc tupdesc, int fnumber);
extern Oid SPI_gettypeid(TupleDesc tupdesc, int fnumber);
extern char *SPI_getrelname(Relation rel);
extern char *SPI_getnspname(Relation rel);
extern void *SPI_palloc(Size size);
extern void *SPI_repalloc(void *pointer, Size size);
extern void SPI_pfree(void *pointer);
extern Datum SPI_datumTransfer(Datum value, bool typByVal, int typLen);
extern void SPI_freetuple(HeapTuple pointer);
extern void SPI_freetuptable(SPITupleTable *tuptable);
extern Portal SPI_cursor_open(const char *name, SPIPlanPtr plan,
Datum *Values, const char *Nulls, bool read_only);
extern Portal SPI_cursor_open_with_args(const char *name,
const char *src,
int nargs, Oid *argtypes,
Datum *Values, const char *Nulls,
bool read_only, int cursorOptions);
extern Portal SPI_cursor_open_with_paramlist(const char *name, SPIPlanPtr plan,
ParamListInfo params, bool read_only);
extern Portal SPI_cursor_find(const char *name);
extern void SPI_cursor_fetch(Portal portal, bool forward, long count);
extern void SPI_cursor_move(Portal portal, bool forward, long count);
extern void SPI_scroll_cursor_fetch(Portal, FetchDirection direction, long count);
extern void SPI_scroll_cursor_move(Portal, FetchDirection direction, long count);
extern void SPI_cursor_close(Portal portal);
extern int SPI_register_relation(EphemeralNamedRelation enr);
extern int SPI_unregister_relation(const char *name);
extern int SPI_register_trigger_data(TriggerData *tdata);
extern void SPI_start_transaction(void);
extern void SPI_commit(void);
extern void SPI_rollback(void);
extern void AtEOXact_SPI(bool isCommit);
extern void AtEOSubXact_SPI(bool isCommit, SubTransactionId mySubid);
#endif /* SPI_H */
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