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Speed up plpgsql trigger startup by introducing "promises". 

Over the years we've accreted quite a few special variables that are
predefined in plpgsql trigger functions.  The cost of initializing these
variables to their defined values turns out to be a significant part of
the runtime of simple triggers; but, undoubtedly, most real-world triggers
never examine the values of most of these variables.

To improve matters, invent the notion of a variable that has a "promise"
attached to it, specifying which of the predetermined values should be
assigned to the variable if anything ever reads it.  This eliminates all
the unneeded startup overhead, in return for a small penalty on accesses
to these variables.

Tom Lane, reviewed by Pavel Stehule

Discussion: https://postgr.es/m/11986.1514407114@sss.pgh.pa.us
This commit is contained in:
Tom Lane 2018-02-13 19:20:37 -05:00
parent 40301c1c8b
commit fd333bc763
5 changed files with 306 additions and 142 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

50
src/pl/plpgsql/src/pl_comp.c
View File

@ -607,7 +607,9 @@ do_compile(FunctionCallInfo fcinfo,
-1,
InvalidOid),
true);
function->tg_name_varno = var->dno;
Assert(var->dtype == PLPGSQL_DTYPE_VAR);
var->dtype = PLPGSQL_DTYPE_PROMISE;
((PLpgSQL_var *) var)->promise = PLPGSQL_PROMISE_TG_NAME;
/* Add the variable tg_when */
var = plpgsql_build_variable("tg_when", 0,
@ -615,7 +617,9 @@ do_compile(FunctionCallInfo fcinfo,
-1,
function->fn_input_collation),
true);
function->tg_when_varno = var->dno;
Assert(var->dtype == PLPGSQL_DTYPE_VAR);
var->dtype = PLPGSQL_DTYPE_PROMISE;
((PLpgSQL_var *) var)->promise = PLPGSQL_PROMISE_TG_WHEN;
/* Add the variable tg_level */
var = plpgsql_build_variable("tg_level", 0,
@ -623,7 +627,9 @@ do_compile(FunctionCallInfo fcinfo,
-1,
function->fn_input_collation),
true);
function->tg_level_varno = var->dno;
Assert(var->dtype == PLPGSQL_DTYPE_VAR);
var->dtype = PLPGSQL_DTYPE_PROMISE;
((PLpgSQL_var *) var)->promise = PLPGSQL_PROMISE_TG_LEVEL;
/* Add the variable tg_op */
var = plpgsql_build_variable("tg_op", 0,
@ -631,7 +637,9 @@ do_compile(FunctionCallInfo fcinfo,
-1,
function->fn_input_collation),
true);
function->tg_op_varno = var->dno;
Assert(var->dtype == PLPGSQL_DTYPE_VAR);
var->dtype = PLPGSQL_DTYPE_PROMISE;
((PLpgSQL_var *) var)->promise = PLPGSQL_PROMISE_TG_OP;
/* Add the variable tg_relid */
var = plpgsql_build_variable("tg_relid", 0,
@ -639,7 +647,9 @@ do_compile(FunctionCallInfo fcinfo,
-1,
InvalidOid),
true);
function->tg_relid_varno = var->dno;
Assert(var->dtype == PLPGSQL_DTYPE_VAR);
var->dtype = PLPGSQL_DTYPE_PROMISE;
((PLpgSQL_var *) var)->promise = PLPGSQL_PROMISE_TG_RELID;
/* Add the variable tg_relname */
var = plpgsql_build_variable("tg_relname", 0,
@ -647,7 +657,9 @@ do_compile(FunctionCallInfo fcinfo,
-1,
InvalidOid),
true);
function->tg_relname_varno = var->dno;
Assert(var->dtype == PLPGSQL_DTYPE_VAR);
var->dtype = PLPGSQL_DTYPE_PROMISE;
((PLpgSQL_var *) var)->promise = PLPGSQL_PROMISE_TG_TABLE_NAME;
/* tg_table_name is now preferred to tg_relname */
var = plpgsql_build_variable("tg_table_name", 0,
@ -655,7 +667,9 @@ do_compile(FunctionCallInfo fcinfo,
-1,
InvalidOid),
true);
function->tg_table_name_varno = var->dno;
Assert(var->dtype == PLPGSQL_DTYPE_VAR);
var->dtype = PLPGSQL_DTYPE_PROMISE;
((PLpgSQL_var *) var)->promise = PLPGSQL_PROMISE_TG_TABLE_NAME;
/* add the variable tg_table_schema */
var = plpgsql_build_variable("tg_table_schema", 0,
@ -663,7 +677,9 @@ do_compile(FunctionCallInfo fcinfo,
-1,
InvalidOid),
true);
function->tg_table_schema_varno = var->dno;
Assert(var->dtype == PLPGSQL_DTYPE_VAR);
var->dtype = PLPGSQL_DTYPE_PROMISE;
((PLpgSQL_var *) var)->promise = PLPGSQL_PROMISE_TG_TABLE_SCHEMA;
/* Add the variable tg_nargs */
var = plpgsql_build_variable("tg_nargs", 0,
@ -671,7 +687,9 @@ do_compile(FunctionCallInfo fcinfo,
-1,
InvalidOid),
true);
function->tg_nargs_varno = var->dno;
Assert(var->dtype == PLPGSQL_DTYPE_VAR);
var->dtype = PLPGSQL_DTYPE_PROMISE;
((PLpgSQL_var *) var)->promise = PLPGSQL_PROMISE_TG_NARGS;
/* Add the variable tg_argv */
var = plpgsql_build_variable("tg_argv", 0,
@ -679,7 +697,9 @@ do_compile(FunctionCallInfo fcinfo,
-1,
function->fn_input_collation),
true);
function->tg_argv_varno = var->dno;
Assert(var->dtype == PLPGSQL_DTYPE_VAR);
var->dtype = PLPGSQL_DTYPE_PROMISE;
((PLpgSQL_var *) var)->promise = PLPGSQL_PROMISE_TG_ARGV;
break;
@ -701,7 +721,9 @@ do_compile(FunctionCallInfo fcinfo,
-1,
function->fn_input_collation),
true);
function->tg_event_varno = var->dno;
Assert(var->dtype == PLPGSQL_DTYPE_VAR);
var->dtype = PLPGSQL_DTYPE_PROMISE;
((PLpgSQL_var *) var)->promise = PLPGSQL_PROMISE_TG_EVENT;
/* Add the variable tg_tag */
var = plpgsql_build_variable("tg_tag", 0,
@ -709,7 +731,9 @@ do_compile(FunctionCallInfo fcinfo,
-1,
function->fn_input_collation),
true);
function->tg_tag_varno = var->dno;
Assert(var->dtype == PLPGSQL_DTYPE_VAR);
var->dtype = PLPGSQL_DTYPE_PROMISE;
((PLpgSQL_var *) var)->promise = PLPGSQL_PROMISE_TG_TAG;
break;
@ -1878,6 +1902,7 @@ build_row_from_vars(PLpgSQL_variable **vars, int numvars)
switch (var->dtype)
{
case PLPGSQL_DTYPE_VAR:
case PLPGSQL_DTYPE_PROMISE:
typoid = ((PLpgSQL_var *) var)->datatype->typoid;
typmod = ((PLpgSQL_var *) var)->datatype->atttypmod;
typcoll = ((PLpgSQL_var *) var)->datatype->collation;
@ -2196,6 +2221,7 @@ plpgsql_finish_datums(PLpgSQL_function *function)
switch (function->datums[i]->dtype)
{
case PLPGSQL_DTYPE_VAR:
case PLPGSQL_DTYPE_PROMISE:
copiable_size += MAXALIGN(sizeof(PLpgSQL_var));
break;
case PLPGSQL_DTYPE_REC:

334
src/pl/plpgsql/src/pl_exec.c
View File

@ -237,6 +237,8 @@ static void coerce_function_result_tuple(PLpgSQL_execstate *estate,
static void plpgsql_exec_error_callback(void *arg);
static void copy_plpgsql_datums(PLpgSQL_execstate *estate,
PLpgSQL_function *func);
static void plpgsql_fulfill_promise(PLpgSQL_execstate *estate,
PLpgSQL_var *var);
static MemoryContext get_stmt_mcontext(PLpgSQL_execstate *estate);
static void push_stmt_mcontext(PLpgSQL_execstate *estate);
static void pop_stmt_mcontext(PLpgSQL_execstate *estate);
@ -547,6 +549,7 @@ plpgsql_exec_function(PLpgSQL_function *func, FunctionCallInfo fcinfo,
break;
default:
/* Anything else should not be an argument variable */
elog(ERROR, "unrecognized dtype: %d", func->datums[i]->dtype);
}
}
@ -834,10 +837,8 @@ plpgsql_exec_trigger(PLpgSQL_function *func,
{
PLpgSQL_execstate estate;
ErrorContextCallback plerrcontext;
int i;
int rc;
TupleDesc tupdesc;
PLpgSQL_var *var;
PLpgSQL_rec *rec_new,
*rec_old;
HeapTuple rettup;
@ -846,6 +847,7 @@ plpgsql_exec_trigger(PLpgSQL_function *func,
* Setup the execution state
*/
plpgsql_estate_setup(&estate, func, NULL, NULL);
estate.trigdata = trigdata;
/*
* Setup error traceback support for ereport()
@ -906,106 +908,6 @@ plpgsql_exec_trigger(PLpgSQL_function *func,
rc = SPI_register_trigger_data(trigdata);
Assert(rc >= 0);
/*
* Assign the special tg_ variables
*/
var = (PLpgSQL_var *) (estate.datums[func->tg_op_varno]);
if (TRIGGER_FIRED_BY_INSERT(trigdata->tg_event))
assign_text_var(&estate, var, "INSERT");
else if (TRIGGER_FIRED_BY_UPDATE(trigdata->tg_event))
assign_text_var(&estate, var, "UPDATE");
else if (TRIGGER_FIRED_BY_DELETE(trigdata->tg_event))
assign_text_var(&estate, var, "DELETE");
else if (TRIGGER_FIRED_BY_TRUNCATE(trigdata->tg_event))
assign_text_var(&estate, var, "TRUNCATE");
else
elog(ERROR, "unrecognized trigger action: not INSERT, DELETE, UPDATE, or TRUNCATE");
var = (PLpgSQL_var *) (estate.datums[func->tg_name_varno]);
assign_simple_var(&estate, var,
DirectFunctionCall1(namein,
CStringGetDatum(trigdata->tg_trigger->tgname)),
false, true);
var = (PLpgSQL_var *) (estate.datums[func->tg_when_varno]);
if (TRIGGER_FIRED_BEFORE(trigdata->tg_event))
assign_text_var(&estate, var, "BEFORE");
else if (TRIGGER_FIRED_AFTER(trigdata->tg_event))
assign_text_var(&estate, var, "AFTER");
else if (TRIGGER_FIRED_INSTEAD(trigdata->tg_event))
assign_text_var(&estate, var, "INSTEAD OF");
else
elog(ERROR, "unrecognized trigger execution time: not BEFORE, AFTER, or INSTEAD OF");
var = (PLpgSQL_var *) (estate.datums[func->tg_level_varno]);
if (TRIGGER_FIRED_FOR_ROW(trigdata->tg_event))
assign_text_var(&estate, var, "ROW");
else if (TRIGGER_FIRED_FOR_STATEMENT(trigdata->tg_event))
assign_text_var(&estate, var, "STATEMENT");
else
elog(ERROR, "unrecognized trigger event type: not ROW or STATEMENT");
var = (PLpgSQL_var *) (estate.datums[func->tg_relid_varno]);
assign_simple_var(&estate, var,
ObjectIdGetDatum(trigdata->tg_relation->rd_id),
false, false);
var = (PLpgSQL_var *) (estate.datums[func->tg_relname_varno]);
assign_simple_var(&estate, var,
DirectFunctionCall1(namein,
CStringGetDatum(RelationGetRelationName(trigdata->tg_relation))),
false, true);
var = (PLpgSQL_var *) (estate.datums[func->tg_table_name_varno]);
assign_simple_var(&estate, var,
DirectFunctionCall1(namein,
CStringGetDatum(RelationGetRelationName(trigdata->tg_relation))),
false, true);
var = (PLpgSQL_var *) (estate.datums[func->tg_table_schema_varno]);
assign_simple_var(&estate, var,
DirectFunctionCall1(namein,
CStringGetDatum(get_namespace_name(
RelationGetNamespace(
trigdata->tg_relation)))),
false, true);
var = (PLpgSQL_var *) (estate.datums[func->tg_nargs_varno]);
assign_simple_var(&estate, var,
Int16GetDatum(trigdata->tg_trigger->tgnargs),
false, false);
var = (PLpgSQL_var *) (estate.datums[func->tg_argv_varno]);
if (trigdata->tg_trigger->tgnargs > 0)
{
/*
* For historical reasons, tg_argv[] subscripts start at zero not one.
* So we can't use construct_array().
*/
int nelems = trigdata->tg_trigger->tgnargs;
Datum *elems;
int dims[1];
int lbs[1];
elems = palloc(sizeof(Datum) * nelems);
for (i = 0; i < nelems; i++)
elems[i] = CStringGetTextDatum(trigdata->tg_trigger->tgargs[i]);
dims[0] = nelems;
lbs[0] = 0;
assign_simple_var(&estate, var,
PointerGetDatum(construct_md_array(elems, NULL,
1, dims, lbs,
TEXTOID,
-1, false, 'i')),
false, true);
}
else
{
assign_simple_var(&estate, var, (Datum) 0, true, false);
}
estate.err_text = gettext_noop("during function entry");
/*
@ -1153,12 +1055,12 @@ plpgsql_exec_event_trigger(PLpgSQL_function *func, EventTriggerData *trigdata)
PLpgSQL_execstate estate;
ErrorContextCallback plerrcontext;
int rc;
PLpgSQL_var *var;
/*
* Setup the execution state
*/
plpgsql_estate_setup(&estate, func, NULL, NULL);
estate.evtrigdata = trigdata;
/*
* Setup error traceback support for ereport()
@ -1174,15 +1076,6 @@ plpgsql_exec_event_trigger(PLpgSQL_function *func, EventTriggerData *trigdata)
estate.err_text = gettext_noop("during initialization of execution state");
copy_plpgsql_datums(&estate, func);
/*
* Assign the special tg_ variables
*/
var = (PLpgSQL_var *) (estate.datums[func->tg_event_varno]);
assign_text_var(&estate, var, trigdata->event);
var = (PLpgSQL_var *) (estate.datums[func->tg_tag_varno]);
assign_text_var(&estate, var, trigdata->tag);
/*
* Let the instrumentation plugin peek at this function
*/
@ -1321,6 +1214,7 @@ copy_plpgsql_datums(PLpgSQL_execstate *estate,
switch (indatum->dtype)
{
case PLPGSQL_DTYPE_VAR:
case PLPGSQL_DTYPE_PROMISE:
outdatum = (PLpgSQL_datum *) ws_next;
memcpy(outdatum, indatum, sizeof(PLpgSQL_var));
ws_next += MAXALIGN(sizeof(PLpgSQL_var));
@ -1356,6 +1250,166 @@ copy_plpgsql_datums(PLpgSQL_execstate *estate,
Assert(ws_next == workspace + func->copiable_size);
}
/*
* If the variable has an armed "promise", compute the promised value
* and assign it to the variable.
* The assignment automatically disarms the promise.
*/
static void
plpgsql_fulfill_promise(PLpgSQL_execstate *estate,
PLpgSQL_var *var)
{
MemoryContext oldcontext;
if (var->promise == PLPGSQL_PROMISE_NONE)
return; /* nothing to do */
/*
* This will typically be invoked in a short-lived context such as the
* mcontext. We must create variable values in the estate's datum
* context. This quick-and-dirty solution risks leaking some additional
* cruft there, but since any one promise is honored at most once per
* function call, it's probably not worth being more careful.
*/
oldcontext = MemoryContextSwitchTo(estate->datum_context);
switch (var->promise)
{
case PLPGSQL_PROMISE_TG_NAME:
if (estate->trigdata == NULL)
elog(ERROR, "trigger promise is not in a trigger function");
assign_simple_var(estate, var,
DirectFunctionCall1(namein,
CStringGetDatum(estate->trigdata->tg_trigger->tgname)),
false, true);
break;
case PLPGSQL_PROMISE_TG_WHEN:
if (estate->trigdata == NULL)
elog(ERROR, "trigger promise is not in a trigger function");
if (TRIGGER_FIRED_BEFORE(estate->trigdata->tg_event))
assign_text_var(estate, var, "BEFORE");
else if (TRIGGER_FIRED_AFTER(estate->trigdata->tg_event))
assign_text_var(estate, var, "AFTER");
else if (TRIGGER_FIRED_INSTEAD(estate->trigdata->tg_event))
assign_text_var(estate, var, "INSTEAD OF");
else
elog(ERROR, "unrecognized trigger execution time: not BEFORE, AFTER, or INSTEAD OF");
break;
case PLPGSQL_PROMISE_TG_LEVEL:
if (estate->trigdata == NULL)
elog(ERROR, "trigger promise is not in a trigger function");
if (TRIGGER_FIRED_FOR_ROW(estate->trigdata->tg_event))
assign_text_var(estate, var, "ROW");
else if (TRIGGER_FIRED_FOR_STATEMENT(estate->trigdata->tg_event))
assign_text_var(estate, var, "STATEMENT");
else
elog(ERROR, "unrecognized trigger event type: not ROW or STATEMENT");
break;
case PLPGSQL_PROMISE_TG_OP:
if (estate->trigdata == NULL)
elog(ERROR, "trigger promise is not in a trigger function");
if (TRIGGER_FIRED_BY_INSERT(estate->trigdata->tg_event))
assign_text_var(estate, var, "INSERT");
else if (TRIGGER_FIRED_BY_UPDATE(estate->trigdata->tg_event))
assign_text_var(estate, var, "UPDATE");
else if (TRIGGER_FIRED_BY_DELETE(estate->trigdata->tg_event))
assign_text_var(estate, var, "DELETE");
else if (TRIGGER_FIRED_BY_TRUNCATE(estate->trigdata->tg_event))
assign_text_var(estate, var, "TRUNCATE");
else
elog(ERROR, "unrecognized trigger action: not INSERT, DELETE, UPDATE, or TRUNCATE");
break;
case PLPGSQL_PROMISE_TG_RELID:
if (estate->trigdata == NULL)
elog(ERROR, "trigger promise is not in a trigger function");
assign_simple_var(estate, var,
ObjectIdGetDatum(estate->trigdata->tg_relation->rd_id),
false, false);
break;
case PLPGSQL_PROMISE_TG_TABLE_NAME:
if (estate->trigdata == NULL)
elog(ERROR, "trigger promise is not in a trigger function");
assign_simple_var(estate, var,
DirectFunctionCall1(namein,
CStringGetDatum(RelationGetRelationName(estate->trigdata->tg_relation))),
false, true);
break;
case PLPGSQL_PROMISE_TG_TABLE_SCHEMA:
if (estate->trigdata == NULL)
elog(ERROR, "trigger promise is not in a trigger function");
assign_simple_var(estate, var,
DirectFunctionCall1(namein,
CStringGetDatum(get_namespace_name(RelationGetNamespace(estate->trigdata->tg_relation)))),
false, true);
break;
case PLPGSQL_PROMISE_TG_NARGS:
if (estate->trigdata == NULL)
elog(ERROR, "trigger promise is not in a trigger function");
assign_simple_var(estate, var,
Int16GetDatum(estate->trigdata->tg_trigger->tgnargs),
false, false);
break;
case PLPGSQL_PROMISE_TG_ARGV:
if (estate->trigdata == NULL)
elog(ERROR, "trigger promise is not in a trigger function");
if (estate->trigdata->tg_trigger->tgnargs > 0)
{
/*
* For historical reasons, tg_argv[] subscripts start at zero
* not one. So we can't use construct_array().
*/
int nelems = estate->trigdata->tg_trigger->tgnargs;
Datum *elems;
int dims[1];
int lbs[1];
int i;
elems = palloc(sizeof(Datum) * nelems);
for (i = 0; i < nelems; i++)
elems[i] = CStringGetTextDatum(estate->trigdata->tg_trigger->tgargs[i]);
dims[0] = nelems;
lbs[0] = 0;
assign_simple_var(estate, var,
PointerGetDatum(construct_md_array(elems, NULL,
1, dims, lbs,
TEXTOID,
-1, false, 'i')),
false, true);
}
else
{
assign_simple_var(estate, var, (Datum) 0, true, false);
}
break;
case PLPGSQL_PROMISE_TG_EVENT:
if (estate->evtrigdata == NULL)
elog(ERROR, "event trigger promise is not in an event trigger function");
assign_text_var(estate, var, estate->evtrigdata->event);
break;
case PLPGSQL_PROMISE_TG_TAG:
if (estate->evtrigdata == NULL)
elog(ERROR, "event trigger promise is not in an event trigger function");
assign_text_var(estate, var, estate->evtrigdata->tag);
break;
default:
elog(ERROR, "unrecognized promise type: %d", var->promise);
}
MemoryContextSwitchTo(oldcontext);
}
/*
* Create a memory context for statement-lifespan variables, if we don't
* have one already. It will be a child of stmt_mcontext_parent, which is
@ -1464,6 +1518,10 @@ exec_stmt_block(PLpgSQL_execstate *estate, PLpgSQL_stmt_block *block)
/*
* The set of dtypes handled here must match plpgsql_add_initdatums().
*
* Note that we currently don't support promise datums within blocks,
* only at a function's outermost scope, so we needn't handle those
* here.
*/
switch (datum->dtype)
{
@ -2778,6 +2836,12 @@ exec_stmt_return(PLpgSQL_execstate *estate, PLpgSQL_stmt_return *stmt)
switch (retvar->dtype)
{
case PLPGSQL_DTYPE_PROMISE:
/* fulfill promise if needed, then handle like regular var */
plpgsql_fulfill_promise(estate, (PLpgSQL_var *) retvar);
/* FALL THRU */
case PLPGSQL_DTYPE_VAR:
{
PLpgSQL_var *var = (PLpgSQL_var *) retvar;
@ -2917,6 +2981,12 @@ exec_stmt_return_next(PLpgSQL_execstate *estate,
switch (retvar->dtype)
{
case PLPGSQL_DTYPE_PROMISE:
/* fulfill promise if needed, then handle like regular var */
plpgsql_fulfill_promise(estate, (PLpgSQL_var *) retvar);
/* FALL THRU */
case PLPGSQL_DTYPE_VAR:
{
PLpgSQL_var *var = (PLpgSQL_var *) retvar;
@ -3487,6 +3557,8 @@ plpgsql_estate_setup(PLpgSQL_execstate *estate,
func->cur_estate = estate;
estate->func = func;
estate->trigdata = NULL;
estate->evtrigdata = NULL;
estate->retval = (Datum) 0;
estate->retisnull = true;
@ -4542,6 +4614,7 @@ exec_assign_value(PLpgSQL_execstate *estate,
switch (target->dtype)
{
case PLPGSQL_DTYPE_VAR:
case PLPGSQL_DTYPE_PROMISE:
{
/*
* Target is a variable
@ -4604,10 +4677,16 @@ exec_assign_value(PLpgSQL_execstate *estate,
* cannot reliably be made any earlier; we have to be looking
* at the object's standard R/W pointer to be sure pointer
* equality is meaningful.
*
* Also, if it's a promise variable, we should disarm the
* promise in any case --- otherwise, assigning null to an
* armed promise variable would fail to disarm the promise.
*/
if (var->value != newvalue || var->isnull || isNull)
assign_simple_var(estate, var, newvalue, isNull,
(!var->datatype->typbyval && !isNull));
else
var->promise = PLPGSQL_PROMISE_NONE;
break;
}
@ -4951,6 +5030,12 @@ exec_eval_datum(PLpgSQL_execstate *estate,
switch (datum->dtype)
{
case PLPGSQL_DTYPE_PROMISE:
/* fulfill promise if needed, then handle like regular var */
plpgsql_fulfill_promise(estate, (PLpgSQL_var *) datum);
/* FALL THRU */
case PLPGSQL_DTYPE_VAR:
{
PLpgSQL_var *var = (PLpgSQL_var *) datum;
@ -5093,6 +5178,7 @@ plpgsql_exec_get_datum_type(PLpgSQL_execstate *estate,
switch (datum->dtype)
{
case PLPGSQL_DTYPE_VAR:
case PLPGSQL_DTYPE_PROMISE:
{
PLpgSQL_var *var = (PLpgSQL_var *) datum;
@ -5176,6 +5262,7 @@ plpgsql_exec_get_datum_type_info(PLpgSQL_execstate *estate,
switch (datum->dtype)
{
case PLPGSQL_DTYPE_VAR:
case PLPGSQL_DTYPE_PROMISE:
{
PLpgSQL_var *var = (PLpgSQL_var *) datum;
@ -5874,6 +5961,7 @@ plpgsql_param_fetch(ParamListInfo params,
switch (datum->dtype)
{
case PLPGSQL_DTYPE_VAR:
case PLPGSQL_DTYPE_PROMISE:
/* always safe */
break;
@ -5989,8 +6077,8 @@ plpgsql_param_compile(ParamListInfo params, Param *param,
* Select appropriate eval function. It seems worth special-casing
* DTYPE_VAR and DTYPE_RECFIELD for performance. Also, we can determine
* in advance whether MakeExpandedObjectReadOnly() will be required.
* Currently, only VAR and REC datums could contain read/write expanded
* objects.
* Currently, only VAR/PROMISE and REC datums could contain read/write
* expanded objects.
*/
if (datum->dtype == PLPGSQL_DTYPE_VAR)
{
@ -6002,6 +6090,14 @@ plpgsql_param_compile(ParamListInfo params, Param *param,
}
else if (datum->dtype == PLPGSQL_DTYPE_RECFIELD)
scratch.d.cparam.paramfunc = plpgsql_param_eval_recfield;
else if (datum->dtype == PLPGSQL_DTYPE_PROMISE)
{
if (dno != expr->rwparam &&
((PLpgSQL_var *) datum)->datatype->typlen == -1)
scratch.d.cparam.paramfunc = plpgsql_param_eval_generic_ro;
else
scratch.d.cparam.paramfunc = plpgsql_param_eval_generic;
}
else if (datum->dtype == PLPGSQL_DTYPE_REC &&
dno != expr->rwparam)
scratch.d.cparam.paramfunc = plpgsql_param_eval_generic_ro;
@ -7680,7 +7776,8 @@ static void
assign_simple_var(PLpgSQL_execstate *estate, PLpgSQL_var *var,
Datum newvalue, bool isnull, bool freeable)
{
Assert(var->dtype == PLPGSQL_DTYPE_VAR);
Assert(var->dtype == PLPGSQL_DTYPE_VAR ||
var->dtype == PLPGSQL_DTYPE_PROMISE);
/* Free the old value if needed */
if (var->freeval)
{
@ -7695,6 +7792,13 @@ assign_simple_var(PLpgSQL_execstate *estate, PLpgSQL_var *var,
var->value = newvalue;
var->isnull = isnull;
var->freeval = freeable;
/*
* If it's a promise variable, then either we just assigned the promised
* value, or the user explicitly assigned an overriding value. Either
* way, cancel the promise.
*/
var->promise = PLPGSQL_PROMISE_NONE;
}
/*

5
src/pl/plpgsql/src/pl_funcs.c
View File

@ -729,6 +729,7 @@ plpgsql_free_function_memory(PLpgSQL_function *func)
switch (d->dtype)
{
case PLPGSQL_DTYPE_VAR:
case PLPGSQL_DTYPE_PROMISE:
{
PLpgSQL_var *var = (PLpgSQL_var *) d;
@ -1582,6 +1583,7 @@ plpgsql_dumptree(PLpgSQL_function *func)
switch (d->dtype)
{
case PLPGSQL_DTYPE_VAR:
case PLPGSQL_DTYPE_PROMISE:
{
PLpgSQL_var *var = (PLpgSQL_var *) d;
@ -1608,6 +1610,9 @@ plpgsql_dumptree(PLpgSQL_function *func)
dump_expr(var->cursor_explicit_expr);
printf("\n");
}
if (var->promise != PLPGSQL_PROMISE_NONE)
printf(" PROMISE %d\n",
(int) var->promise);
}
break;
case PLPGSQL_DTYPE_ROW:

3
src/pl/plpgsql/src/pl_gram.y
View File

@ -3170,6 +3170,7 @@ make_return_stmt(int location)
if (tok == T_DATUM && plpgsql_peek() == ';' &&
(yylval.wdatum.datum->dtype == PLPGSQL_DTYPE_VAR ||
yylval.wdatum.datum->dtype == PLPGSQL_DTYPE_PROMISE ||
yylval.wdatum.datum->dtype == PLPGSQL_DTYPE_ROW ||
yylval.wdatum.datum->dtype == PLPGSQL_DTYPE_REC))
{
@ -3231,6 +3232,7 @@ make_return_next_stmt(int location)
if (tok == T_DATUM && plpgsql_peek() == ';' &&
(yylval.wdatum.datum->dtype == PLPGSQL_DTYPE_VAR ||
yylval.wdatum.datum->dtype == PLPGSQL_DTYPE_PROMISE ||
yylval.wdatum.datum->dtype == PLPGSQL_DTYPE_ROW ||
yylval.wdatum.datum->dtype == PLPGSQL_DTYPE_REC))
{
@ -3318,6 +3320,7 @@ check_assignable(PLpgSQL_datum *datum, int location)
switch (datum->dtype)
{
case PLPGSQL_DTYPE_VAR:
case PLPGSQL_DTYPE_PROMISE:
if (((PLpgSQL_var *) datum)->isconst)
ereport(ERROR,
(errcode(ERRCODE_ERROR_IN_ASSIGNMENT),

56
src/pl/plpgsql/src/plpgsql.h
View File

@ -63,9 +63,29 @@ typedef enum PLpgSQL_datum_type
PLPGSQL_DTYPE_ROW,
PLPGSQL_DTYPE_REC,
PLPGSQL_DTYPE_RECFIELD,
PLPGSQL_DTYPE_ARRAYELEM
PLPGSQL_DTYPE_ARRAYELEM,
PLPGSQL_DTYPE_PROMISE
} PLpgSQL_datum_type;
/*
* DTYPE_PROMISE datums have these possible ways of computing the promise
*/
typedef enum PLpgSQL_promise_type
{
PLPGSQL_PROMISE_NONE = 0, /* not a promise, or promise satisfied */
PLPGSQL_PROMISE_TG_NAME,
PLPGSQL_PROMISE_TG_WHEN,
PLPGSQL_PROMISE_TG_LEVEL,
PLPGSQL_PROMISE_TG_OP,
PLPGSQL_PROMISE_TG_RELID,
PLPGSQL_PROMISE_TG_TABLE_NAME,
PLPGSQL_PROMISE_TG_TABLE_SCHEMA,
PLPGSQL_PROMISE_TG_NARGS,
PLPGSQL_PROMISE_TG_ARGV,
PLPGSQL_PROMISE_TG_EVENT,
PLPGSQL_PROMISE_TG_TAG
} PLpgSQL_promise_type;
/*
* Variants distinguished in PLpgSQL_type structs
*/
@ -248,6 +268,14 @@ typedef struct PLpgSQL_variable
/*
* Scalar variable
*
* DTYPE_VAR and DTYPE_PROMISE datums both use this struct type.
* A PROMISE datum works exactly like a VAR datum for most purposes,
* but if it is read without having previously been assigned to, then
* a special "promised" value is computed and assigned to the datum
* before the read is performed. This technique avoids the overhead of
* computing the variable's value in cases where we expect that many
* functions will never read it.
*/
typedef struct PLpgSQL_var
{
@ -271,9 +299,18 @@ typedef struct PLpgSQL_var
int cursor_explicit_argrow;
int cursor_options;
/* Fields below here can change at runtime */
Datum value;
bool isnull;
bool freeval;
/*
* The promise field records which "promised" value to assign if the
* promise must be honored. If it's a normal variable, or the promise has
* been fulfilled, this is PLPGSQL_PROMISE_NONE.
*/
PLpgSQL_promise_type promise;
} PLpgSQL_var;
/*
@ -869,20 +906,6 @@ typedef struct PLpgSQL_function
int found_varno;
int new_varno;
int old_varno;
int tg_name_varno;
int tg_when_varno;
int tg_level_varno;
int tg_op_varno;
int tg_relid_varno;
int tg_relname_varno;
int tg_table_name_varno;
int tg_table_schema_varno;
int tg_nargs_varno;
int tg_argv_varno;
/* for event triggers */
int tg_event_varno;
int tg_tag_varno;
PLpgSQL_resolve_option resolve_option;
@ -912,6 +935,9 @@ typedef struct PLpgSQL_execstate
{
PLpgSQL_function *func; /* function being executed */
TriggerData *trigdata; /* if regular trigger, data about firing */
EventTriggerData *evtrigdata; /* if event trigger, data about firing */
Datum retval;
bool retisnull;
Oid rettype; /* type of current retval */