From b2c4071299e02ed96d48d3c8e776de2fab36f88c Mon Sep 17 00:00:00 2001 From: Tom Lane Date: Mon, 13 Sep 2004 20:10:13 +0000 Subject: Redesign query-snapshot timing so that volatile functions in READ COMMITTED mode see a fresh snapshot for each command in the function, rather than using the latest interactive command's snapshot. Also, suppress fresh snapshots as well as CommandCounterIncrement inside STABLE and IMMUTABLE functions, instead using the snapshot taken for the most closely nested regular query. (This behavior is only sane for read-only functions, so the patch also enforces that such functions contain only SELECT commands.) As per my proposal of 6-Sep-2004; I note that I floated essentially the same proposal on 19-Jun-2002, but that discussion tailed off without any action. Since 8.0 seems like the right place to be taking possibly nontrivial backwards compatibility hits, let's get it done now. --- src/pl/plpython/plpython.c | 50 ++++++++++++++++++++++++++++++---------------- 1 file changed, 33 insertions(+), 17 deletions(-) (limited to 'src/pl/plpython/plpython.c') diff --git a/src/pl/plpython/plpython.c b/src/pl/plpython/plpython.c index ecbf2dbce8a..dd4ef3e455a 100644 --- a/src/pl/plpython/plpython.c +++ b/src/pl/plpython/plpython.c @@ -29,7 +29,7 @@ * MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS. * * IDENTIFICATION - * $PostgreSQL: pgsql/src/pl/plpython/plpython.c,v 1.55 2004/08/30 02:54:42 momjian Exp $ + * $PostgreSQL: pgsql/src/pl/plpython/plpython.c,v 1.56 2004/09/13 20:09:30 tgl Exp $ * ********************************************************************* */ @@ -131,6 +131,7 @@ typedef struct PLyProcedure char *pyname; /* Python name of procedure */ TransactionId fn_xmin; CommandId fn_cmin; + bool fn_readonly; PLyTypeInfo result; /* also used to store info for trigger * tuple type */ PLyTypeInfo args[FUNC_MAX_ARGS]; @@ -257,11 +258,9 @@ static PyObject *PLyString_FromString(const char *); static int PLy_first_call = 1; /* - * Last function called by postgres backend - * - * XXX replace this with errcontext mechanism + * Currently active plpython function */ -static PLyProcedure *PLy_last_procedure = NULL; +static PLyProcedure *PLy_curr_procedure = NULL; /* * When a callback from Python into PG incurs an error, we temporarily store @@ -322,6 +321,7 @@ Datum plpython_call_handler(PG_FUNCTION_ARGS) { Datum retval; + PLyProcedure *save_curr_proc; PLyProcedure *volatile proc = NULL; PLy_init_all(); @@ -329,6 +329,8 @@ plpython_call_handler(PG_FUNCTION_ARGS) if (SPI_connect() != SPI_OK_CONNECT) elog(ERROR, "could not connect to SPI manager"); + save_curr_proc = PLy_curr_procedure; + PG_TRY(); { if (CALLED_AS_TRIGGER(fcinfo)) @@ -338,17 +340,20 @@ plpython_call_handler(PG_FUNCTION_ARGS) proc = PLy_procedure_get(fcinfo, RelationGetRelid(tdata->tg_relation)); + PLy_curr_procedure = proc; trv = PLy_trigger_handler(fcinfo, proc); retval = PointerGetDatum(trv); } else { proc = PLy_procedure_get(fcinfo, InvalidOid); + PLy_curr_procedure = proc; retval = PLy_function_handler(fcinfo, proc); } } PG_CATCH(); { + PLy_curr_procedure = save_curr_proc; if (proc) { /* note: Py_DECREF needs braces around it, as of 2003/08 */ @@ -359,6 +364,8 @@ plpython_call_handler(PG_FUNCTION_ARGS) } PG_END_TRY(); + PLy_curr_procedure = save_curr_proc; + Py_DECREF(proc->me); return retval; @@ -795,14 +802,10 @@ static PyObject * PLy_procedure_call(PLyProcedure * proc, char *kargs, PyObject * vargs) { PyObject *rv; - PLyProcedure *current; - current = PLy_last_procedure; - PLy_last_procedure = proc; PyDict_SetItemString(proc->globals, kargs, vargs); rv = PyEval_EvalCode((PyCodeObject *) proc->code, proc->globals, proc->globals); - PLy_last_procedure = current; /* * If there was an error in a PG callback, propagate that no matter @@ -1005,6 +1008,9 @@ PLy_procedure_create(FunctionCallInfo fcinfo, Oid tgreloid, strcpy(proc->pyname, procName); proc->fn_xmin = HeapTupleHeaderGetXmin(procTup->t_data); proc->fn_cmin = HeapTupleHeaderGetCmin(procTup->t_data); + /* Remember if function is STABLE/IMMUTABLE */ + proc->fn_readonly = + (procStruct->provolatile != PROVOLATILE_VOLATILE); PLy_typeinfo_init(&proc->result); for (i = 0; i < FUNC_MAX_ARGS; i++) PLy_typeinfo_init(&proc->args[i]); @@ -1935,7 +1941,8 @@ PLy_spi_prepare(PyObject * self, PyObject * args) PyErr_SetString(PLy_exc_spi_error, "Unknown error in PLy_spi_prepare"); /* XXX this oughta be replaced with errcontext mechanism */ - PLy_elog(WARNING, "in function %s:", PLy_procedure_name(PLy_last_procedure)); + PLy_elog(WARNING, "in function %s:", + PLy_procedure_name(PLy_curr_procedure)); return NULL; } PG_END_TRY(); @@ -2054,7 +2061,8 @@ PLy_spi_execute_plan(PyObject * ob, PyObject * list, int limit) } } - rv = SPI_execp(plan->plan, plan->values, nulls, limit); + rv = SPI_execute_plan(plan->plan, plan->values, nulls, + PLy_curr_procedure->fn_readonly, limit); pfree(nulls); } @@ -2080,7 +2088,9 @@ PLy_spi_execute_plan(PyObject * ob, PyObject * list, int limit) if (!PyErr_Occurred()) PyErr_SetString(PLy_exc_error, "Unknown error in PLy_spi_execute_plan"); - PLy_elog(WARNING, "in function %s:", PLy_procedure_name(PLy_last_procedure)); + /* XXX this oughta be replaced with errcontext mechanism */ + PLy_elog(WARNING, "in function %s:", + PLy_procedure_name(PLy_curr_procedure)); return NULL; } PG_END_TRY(); @@ -2098,7 +2108,7 @@ PLy_spi_execute_plan(PyObject * ob, PyObject * list, int limit) if (rv < 0) { PLy_exception_set(PLy_exc_spi_error, - "SPI_execp failed: %s", + "SPI_execute_plan failed: %s", SPI_result_code_string(rv)); return NULL; } @@ -2114,7 +2124,9 @@ PLy_spi_execute_query(char *query, int limit) oldcontext = CurrentMemoryContext; PG_TRY(); - rv = SPI_exec(query, limit); + { + rv = SPI_execute(query, PLy_curr_procedure->fn_readonly, limit); + } PG_CATCH(); { MemoryContextSwitchTo(oldcontext); @@ -2123,7 +2135,9 @@ PLy_spi_execute_query(char *query, int limit) if (!PyErr_Occurred()) PyErr_SetString(PLy_exc_spi_error, "Unknown error in PLy_spi_execute_query"); - PLy_elog(WARNING, "in function %s:", PLy_procedure_name(PLy_last_procedure)); + /* XXX this oughta be replaced with errcontext mechanism */ + PLy_elog(WARNING, "in function %s:", + PLy_procedure_name(PLy_curr_procedure)); return NULL; } PG_END_TRY(); @@ -2131,7 +2145,7 @@ PLy_spi_execute_query(char *query, int limit) if (rv < 0) { PLy_exception_set(PLy_exc_spi_error, - "SPI_exec failed: %s", + "SPI_execute failed: %s", SPI_result_code_string(rv)); return NULL; } @@ -2375,7 +2389,9 @@ PLy_output(volatile int level, PyObject * self, PyObject * args) oldcontext = CurrentMemoryContext; PG_TRY(); - elog(level, "%s", sv); + { + elog(level, "%s", sv); + } PG_CATCH(); { MemoryContextSwitchTo(oldcontext); -- cgit v1.2.3