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Commit8b51083

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Restructure plpgsql's caching of 'simple' expression evaluation trees
to be less dangerous, and often faster as well. ExprState trees arenot kept across transaction boundaries; this eliminates problems withresource leakage in failed transactions. But by keeping them in aper-transaction EState, we can safely arrange for a single ExprStateto be shared by all the expression evaluations done in a given plpgsqlfunction call. (Formerly it seemed necessary to create and destroy anExprState for each exec_eval_simple_expr() call.) This saves time inany scenario where a plpgsql function executes more than one expression.Seems to be about as fast as 7.3 for simple cases, and significantlyfaster for functions that do a lot of calculations.
1 parent8934790 commit8b51083

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3 files changed

+160
-80
lines changed

3 files changed

+160
-80
lines changed

‎src/pl/plpgsql/src/pl_exec.c

Lines changed: 145 additions & 71 deletions
Original file line numberDiff line numberDiff line change
@@ -3,7 +3,7 @@
33
* procedural language
44
*
55
* IDENTIFICATION
6-
* $Header: /cvsroot/pgsql/src/pl/plpgsql/src/pl_exec.c,v 1.91 2003/09/25 23:02:12 tgl Exp $
6+
* $Header: /cvsroot/pgsql/src/pl/plpgsql/src/pl_exec.c,v 1.92 2003/09/28 23:37:45 tgl Exp $
77
*
88
* This software is copyrighted by Jan Wieck - Hamburg.
99
*
@@ -57,6 +57,19 @@
5757

5858
staticconstchar*constraise_skip_msg="RAISE";
5959

60+
/*
61+
* All plpgsql function executions within a single transaction share
62+
* the same executor EState for evaluating "simple" expressions. Each
63+
* function call creates its own "eval_econtext" ExprContext within this
64+
* estate. We destroy the estate at transaction shutdown to ensure there
65+
* is no permanent leakage of memory (especially for xact abort case).
66+
*
67+
* If a simple PLpgSQL_expr has been used in the current xact, it is
68+
* linked into the active_simple_exprs list.
69+
*/
70+
staticEState*simple_eval_estate=NULL;
71+
staticPLpgSQL_expr*active_simple_exprs=NULL;
72+
6073
/************************************************************
6174
* Local function forward declarations
6275
************************************************************/
@@ -135,7 +148,7 @@ static void exec_eval_datum(PLpgSQL_execstate * estate,
135148
Oid*typeid,
136149
Datum*value,
137150
bool*isnull);
138-
staticintexec_eval_subscript(PLpgSQL_execstate*estate,
151+
staticintexec_eval_integer(PLpgSQL_execstate*estate,
139152
PLpgSQL_expr*expr,
140153
bool*isNull);
141154
staticDatumexec_eval_expr(PLpgSQL_execstate*estate,
@@ -381,6 +394,9 @@ plpgsql_exec_function(PLpgSQL_function * func, FunctionCallInfo fcinfo)
381394
}
382395

383396
/* Clean up any leftover temporary memory */
397+
if (estate.eval_econtext!=NULL)
398+
FreeExprContext(estate.eval_econtext);
399+
estate.eval_econtext=NULL;
384400
exec_eval_cleanup(&estate);
385401

386402
/*
@@ -653,6 +669,9 @@ plpgsql_exec_trigger(PLpgSQL_function * func,
653669
}
654670

655671
/* Clean up any leftover temporary memory */
672+
if (estate.eval_econtext!=NULL)
673+
FreeExprContext(estate.eval_econtext);
674+
estate.eval_econtext=NULL;
656675
exec_eval_cleanup(&estate);
657676

658677
/*
@@ -1915,10 +1934,9 @@ exec_eval_cleanup(PLpgSQL_execstate * estate)
19151934
SPI_freetuptable(estate->eval_tuptable);
19161935
estate->eval_tuptable=NULL;
19171936

1918-
/* Clear result of exec_eval_simple_expr */
1937+
/* Clear result of exec_eval_simple_expr(but keep the econtext)*/
19191938
if (estate->eval_econtext!=NULL)
1920-
FreeExprContext(estate->eval_econtext);
1921-
estate->eval_econtext=NULL;
1939+
ResetExprContext(estate->eval_econtext);
19221940
}
19231941

19241942

@@ -1962,7 +1980,7 @@ exec_prepare_plan(PLpgSQL_execstate * estate,
19621980
expr->plan=SPI_saveplan(plan);
19631981
spi_plan= (_SPI_plan*)expr->plan;
19641982
expr->plan_argtypes=spi_plan->argtypes;
1965-
expr->plan_simple_expr=NULL;
1983+
expr->expr_simple_expr=NULL;
19661984
exec_simple_check_plan(expr);
19671985

19681986
SPI_freeplan(plan);
@@ -2931,9 +2949,9 @@ exec_assign_value(PLpgSQL_execstate * estate,
29312949
boolsubisnull;
29322950

29332951
subscriptvals[i]=
2934-
exec_eval_subscript(estate,
2935-
subscripts[nsubscripts-1-i],
2936-
&subisnull);
2952+
exec_eval_integer(estate,
2953+
subscripts[nsubscripts-1-i],
2954+
&subisnull);
29372955
havenullsubscript |=subisnull;
29382956
}
29392957

@@ -3065,7 +3083,7 @@ exec_eval_datum(PLpgSQL_execstate * estate,
30653083
casePLPGSQL_DTYPE_TRIGARG:
30663084
trigarg= (PLpgSQL_trigarg*)datum;
30673085
*typeid=TEXTOID;
3068-
tgargno=exec_eval_subscript(estate,trigarg->argnum,isnull);
3086+
tgargno=exec_eval_integer(estate,trigarg->argnum,isnull);
30693087
if (*isnull||tgargno<0||tgargno >=estate->trig_nargs)
30703088
{
30713089
*value= (Datum)0;
@@ -3089,33 +3107,28 @@ exec_eval_datum(PLpgSQL_execstate * estate,
30893107
}
30903108

30913109
/* ----------
3092-
*exec_eval_subscriptHack to allow subscripting ofresultvariables.
3110+
*exec_eval_integerEvaluate an expression, coerceresultto int4
30933111
*
3094-
* The caller may already have an open eval_econtext, which we have to
3095-
* save and restore around the call of exec_eval_expr.
3112+
* Note we do not do exec_eval_cleanup here; the caller must do it at
3113+
* some later point. (We do this because the caller may be holding the
3114+
* results of other, pass-by-reference, expression evaluations, such as
3115+
* an array value to be subscripted. Also see notes in exec_eval_simple_expr
3116+
* about allocation of the parameter array.)
30963117
* ----------
30973118
*/
30983119
staticint
3099-
exec_eval_subscript(PLpgSQL_execstate*estate,
3100-
PLpgSQL_expr*expr,
3101-
bool*isNull)
3120+
exec_eval_integer(PLpgSQL_execstate*estate,
3121+
PLpgSQL_expr*expr,
3122+
bool*isNull)
31023123
{
3103-
ExprContext*save_econtext;
3104-
Datumsubscriptdatum;
3105-
Oidsubscripttypeid;
3106-
intresult;
3124+
Datumexprdatum;
3125+
Oidexprtypeid;
31073126

3108-
save_econtext=estate->eval_econtext;
3109-
estate->eval_econtext=NULL;
3110-
subscriptdatum=exec_eval_expr(estate,expr,isNull,&subscripttypeid);
3111-
subscriptdatum=exec_simple_cast_value(subscriptdatum,
3112-
subscripttypeid,
3113-
INT4OID,-1,
3114-
isNull);
3115-
result=DatumGetInt32(subscriptdatum);
3116-
exec_eval_cleanup(estate);
3117-
estate->eval_econtext=save_econtext;
3118-
returnresult;
3127+
exprdatum=exec_eval_expr(estate,expr,isNull,&exprtypeid);
3128+
exprdatum=exec_simple_cast_value(exprdatum,exprtypeid,
3129+
INT4OID,-1,
3130+
isNull);
3131+
returnDatumGetInt32(exprdatum);
31193132
}
31203133

31213134
/* ----------
@@ -3143,7 +3156,7 @@ exec_eval_expr(PLpgSQL_execstate * estate,
31433156
* If this is a simple expression, bypass SPI and use the executor
31443157
* directly
31453158
*/
3146-
if (expr->plan_simple_expr!=NULL)
3159+
if (expr->expr_simple_expr!=NULL)
31473160
returnexec_eval_simple_expr(estate,expr,isNull,rettype);
31483161

31493162
rc=exec_run_select(estate,expr,2,NULL);
@@ -3262,6 +3275,10 @@ exec_run_select(PLpgSQL_execstate * estate,
32623275
/* ----------
32633276
* exec_eval_simple_expr -Evaluate a simple expression returning
32643277
*a Datum by directly calling ExecEvalExpr().
3278+
*
3279+
* Note: if pass-by-reference, the result is in the eval_econtext's
3280+
* temporary memory context. It will be freed when exec_eval_cleanup
3281+
* is done.
32653282
* ----------
32663283
*/
32673284
staticDatum
@@ -3271,64 +3288,97 @@ exec_eval_simple_expr(PLpgSQL_execstate * estate,
32713288
Oid*rettype)
32723289
{
32733290
Datumretval;
3274-
inti;
32753291
ExprContext*econtext;
32763292
ParamListInfoparamLI;
3293+
inti;
3294+
3295+
/*
3296+
* Pass back previously-determined result type.
3297+
*/
3298+
*rettype=expr->expr_simple_type;
3299+
3300+
/*
3301+
* Create an EState for evaluation of simple expressions, if there's
3302+
* not one already in the current transaction. The EState is made a
3303+
* child of TopTransactionContext so it will have the right lifespan.
3304+
*/
3305+
if (simple_eval_estate==NULL)
3306+
{
3307+
MemoryContextoldcontext;
3308+
3309+
oldcontext=MemoryContextSwitchTo(TopTransactionContext);
3310+
simple_eval_estate=CreateExecutorState();
3311+
MemoryContextSwitchTo(oldcontext);
3312+
}
3313+
3314+
/*
3315+
* Prepare the expression for execution, if it's not been done already
3316+
* in the current transaction.
3317+
*/
3318+
if (expr->expr_simple_state==NULL)
3319+
{
3320+
expr->expr_simple_state=ExecPrepareExpr(expr->expr_simple_expr,
3321+
simple_eval_estate);
3322+
/* Add it to list for cleanup */
3323+
expr->expr_simple_next=active_simple_exprs;
3324+
active_simple_exprs=expr;
3325+
}
32773326

32783327
/*
3279-
* Create an expression contextto hold the arguments and the result
3280-
*of this expression evaluation. This must be a child of the EState
3281-
*we created in the SPI plan's context.
3328+
* Create an expression contextfor simple expressions, if there's
3329+
*not one already in the current function call. This must be a
3330+
*child of simple_eval_estate.
32823331
*/
3283-
econtext=CreateExprContext(expr->plan_simple_estate);
3332+
econtext=estate->eval_econtext;
3333+
if (econtext==NULL)
3334+
{
3335+
econtext=CreateExprContext(simple_eval_estate);
3336+
estate->eval_econtext=econtext;
3337+
}
32843338

32853339
/*
32863340
* Param list can live in econtext's temporary memory context.
3341+
*
3342+
* XXX think about avoiding repeated palloc's for param lists?
3343+
* Beware however that this routine is re-entrant: exec_eval_datum()
3344+
* can call it back for subscript evaluation, and so there can be a
3345+
* need to have more than one active param list.
32873346
*/
32883347
paramLI= (ParamListInfo)
32893348
MemoryContextAlloc(econtext->ecxt_per_tuple_memory,
32903349
(expr->nparams+1)*sizeof(ParamListInfoData));
3291-
econtext->ecxt_param_list_info=paramLI;
32923350

32933351
/*
3294-
* Put the parameter values into the parameter list info of the
3295-
* expression context.
3352+
* Put the parameter values into the parameter list entries.
32963353
*/
3297-
for (i=0;i<expr->nparams;i++,paramLI++)
3354+
for (i=0;i<expr->nparams;i++)
32983355
{
32993356
PLpgSQL_datum*datum=estate->datums[expr->params[i]];
33003357
Oidparamtypeid;
33013358

3302-
paramLI->kind=PARAM_NUM;
3303-
paramLI->id=i+1;
3359+
paramLI[i].kind=PARAM_NUM;
3360+
paramLI[i].id=i+1;
33043361
exec_eval_datum(estate,datum,expr->plan_argtypes[i],
3305-
&paramtypeid,&paramLI->value,&paramLI->isnull);
3362+
&paramtypeid,
3363+
&paramLI[i].value,&paramLI[i].isnull);
33063364
}
3307-
paramLI->kind=PARAM_INVALID;
3365+
paramLI[i].kind=PARAM_INVALID;
33083366

33093367
/*
3310-
*Initialize things
3368+
*Now we can safely make the econtext point to the param list.
33113369
*/
3312-
*rettype=expr->plan_simple_type;
3370+
econtext->ecxt_param_list_info=paramLI;
33133371

33143372
/*
33153373
* Now call the executor to evaluate the expression
33163374
*/
33173375
SPI_push();
3318-
retval=ExecEvalExprSwitchContext(expr->plan_simple_expr,
3376+
retval=ExecEvalExprSwitchContext(expr->expr_simple_state,
33193377
econtext,
33203378
isNull,
33213379
NULL);
33223380
SPI_pop();
33233381

3324-
/*
3325-
* Note: if pass-by-reference, the result is in the econtext's
3326-
* temporary memory context. It will be freed when exec_eval_cleanup
3327-
* is done.
3328-
*/
3329-
Assert(estate->eval_econtext==NULL);
3330-
estate->eval_econtext=econtext;
3331-
33323382
/*
33333383
* That's it.
33343384
*/
@@ -3795,9 +3845,8 @@ exec_simple_check_plan(PLpgSQL_expr * expr)
37953845
_SPI_plan*spi_plan= (_SPI_plan*)expr->plan;
37963846
Plan*plan;
37973847
TargetEntry*tle;
3798-
MemoryContextoldcontext;
37993848

3800-
expr->plan_simple_expr=NULL;
3849+
expr->expr_simple_expr=NULL;
38013850

38023851
/*
38033852
* 1. We can only evaluate queries that resulted in one single
@@ -3842,21 +3891,14 @@ exec_simple_check_plan(PLpgSQL_expr * expr)
38423891
return;
38433892

38443893
/*
3845-
* Yes - this is a simple expression. Prepare to execute it. We need
3846-
* an EState and an expression state tree, which we'll put into the
3847-
* plan context so they will have appropriate lifespan.
3894+
* Yes - this is a simple expression. Mark it as such, and initialize
3895+
* state to "not executing".
38483896
*/
3849-
oldcontext=MemoryContextSwitchTo(spi_plan->plancxt);
3850-
3851-
expr->plan_simple_estate=CreateExecutorState();
3852-
3853-
expr->plan_simple_expr=ExecPrepareExpr(tle->expr,
3854-
expr->plan_simple_estate);
3855-
3856-
MemoryContextSwitchTo(oldcontext);
3857-
3897+
expr->expr_simple_expr=tle->expr;
3898+
expr->expr_simple_state=NULL;
3899+
expr->expr_simple_next=NULL;
38583900
/* Also stash away the expression result type */
3859-
expr->plan_simple_type=exprType((Node*)tle->expr);
3901+
expr->expr_simple_type=exprType((Node*)tle->expr);
38603902
}
38613903

38623904
/*
@@ -3893,3 +3935,35 @@ exec_set_found(PLpgSQL_execstate * estate, bool state)
38933935
var->value= (Datum)state;
38943936
var->isnull= false;
38953937
}
3938+
3939+
/*
3940+
* plpgsql_eoxact --- post-transaction-commit-or-abort cleanup
3941+
*
3942+
* If a simple_eval_estate was created in the current transaction,
3943+
* it has to be cleaned up, and we have to mark all active PLpgSQL_expr
3944+
* structs that are using it as no longer active.
3945+
*/
3946+
void
3947+
plpgsql_eoxact(boolisCommit,void*arg)
3948+
{
3949+
PLpgSQL_expr*expr;
3950+
PLpgSQL_expr*enext;
3951+
3952+
/* Mark all active exprs as inactive */
3953+
for (expr=active_simple_exprs;expr;expr=enext)
3954+
{
3955+
enext=expr->expr_simple_next;
3956+
expr->expr_simple_state=NULL;
3957+
expr->expr_simple_next=NULL;
3958+
}
3959+
active_simple_exprs=NULL;
3960+
/*
3961+
* If we are doing a clean transaction shutdown, free the EState
3962+
* (so that any remaining resources will be released correctly).
3963+
* In an abort, we expect the regular abort recovery procedures to
3964+
* release everything of interest.
3965+
*/
3966+
if (isCommit&&simple_eval_estate)
3967+
FreeExecutorState(simple_eval_estate);
3968+
simple_eval_estate=NULL;
3969+
}

‎src/pl/plpgsql/src/pl_handler.c

Lines changed: 3 additions & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -3,7 +3,7 @@
33
* procedural language
44
*
55
* IDENTIFICATION
6-
* $Header: /cvsroot/pgsql/src/pl/plpgsql/src/pl_handler.c,v 1.17 2003/08/04 00:43:33 momjian Exp $
6+
* $Header: /cvsroot/pgsql/src/pl/plpgsql/src/pl_handler.c,v 1.18 2003/09/28 23:37:45 tgl Exp $
77
*
88
* This software is copyrighted by Jan Wieck - Hamburg.
99
*
@@ -46,7 +46,6 @@
4646

4747
staticintplpgsql_firstcall=1;
4848

49-
voidplpgsql_init(void);
5049
staticvoidplpgsql_init_all(void);
5150

5251

@@ -64,6 +63,8 @@ plpgsql_init(void)
6463

6564
plpgsql_HashTableInit();
6665

66+
RegisterEOXactCallback(plpgsql_eoxact,NULL);
67+
6768
plpgsql_firstcall=0;
6869
}
6970

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