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Commit8abb3cd

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Use the typcache to cache constraints for domain types.
Previously, we cached domain constraints for the life of a query, orreally for the life of the FmgrInfo struct that was used to invokedomain_in() or domain_check(). But plpgsql (and probably other places)are set up to cache such FmgrInfos for the whole lifespan of a session,which meant they could be enforcing really stale sets of constraints.On the other hand, searching pg_constraint once per query gets kind ofexpensive too: testing says that as much as half the runtime of atrivial query such as "SELECT 0::domaintype" went into that.To fix this, delegate the responsibility for tracking a domain'sconstraints to the typcache, which has the infrastructure needed todetect syscache invalidation events that signal possible changes.This not only removes unnecessary repeat reads of pg_constraint,but ensures that we never apply stale constraint data: whatever weuse is the current data according to syscache rules.Unfortunately, the current configuration of the system catalogs meanswe have to flush cached domain-constraint data whenever either pg_typeor pg_constraint changes, which happens rather a lot (eg, creation ordeletion of a temp table will do it). It might be worth rearrangingthings to split pg_constraint into two catalogs, of which the domainconstraint one would probably be very low-traffic. That's a job foranother patch though, and in any case this patch should improve mattersmaterially even with that handicap.This patch makes use of the recently-added memory context reset callbackfeature to manage the lifespan of domain constraint caches, so that wedon't risk deleting a cache that might be in the midst of evaluation.Although this is a bug fix as well as a performance improvement, noback-patch. There haven't been many if any field complaints aboutstale domain constraint checks, so it doesn't seem worth taking therisk of modifying data structures as basic as MemoryContexts in backbranches.
1 parentb8a18ad commit8abb3cd

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10 files changed

+547
-181
lines changed

10 files changed

+547
-181
lines changed

‎src/backend/commands/tablecmds.c

Lines changed: 2 additions & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -4824,7 +4824,7 @@ ATExecAddColumn(List **wqueue, AlteredTableInfo *tab, Relation rel,
48244824
{
48254825
defval= (Expr*)build_column_default(rel,attribute.attnum);
48264826

4827-
if (!defval&&GetDomainConstraints(typeOid)!=NIL)
4827+
if (!defval&&DomainHasConstraints(typeOid))
48284828
{
48294829
OidbaseTypeId;
48304830
int32baseTypeMod;
@@ -7778,7 +7778,7 @@ ATColumnChangeRequiresRewrite(Node *expr, AttrNumber varattno)
77787778
{
77797779
CoerceToDomain*d= (CoerceToDomain*)expr;
77807780

7781-
if (GetDomainConstraints(d->resulttype)!=NIL)
7781+
if (DomainHasConstraints(d->resulttype))
77827782
return true;
77837783
expr= (Node*)d->arg;
77847784
}

‎src/backend/commands/typecmds.c

Lines changed: 0 additions & 127 deletions
Original file line numberDiff line numberDiff line change
@@ -31,15 +31,11 @@
3131
*/
3232
#include"postgres.h"
3333

34-
#include"access/genam.h"
35-
#include"access/heapam.h"
3634
#include"access/htup_details.h"
3735
#include"access/xact.h"
3836
#include"catalog/binary_upgrade.h"
3937
#include"catalog/catalog.h"
40-
#include"catalog/dependency.h"
4138
#include"catalog/heap.h"
42-
#include"catalog/indexing.h"
4339
#include"catalog/objectaccess.h"
4440
#include"catalog/pg_authid.h"
4541
#include"catalog/pg_collation.h"
@@ -59,14 +55,12 @@
5955
#include"executor/executor.h"
6056
#include"miscadmin.h"
6157
#include"nodes/makefuncs.h"
62-
#include"optimizer/planner.h"
6358
#include"optimizer/var.h"
6459
#include"parser/parse_coerce.h"
6560
#include"parser/parse_collate.h"
6661
#include"parser/parse_expr.h"
6762
#include"parser/parse_func.h"
6863
#include"parser/parse_type.h"
69-
#include"utils/acl.h"
7064
#include"utils/builtins.h"
7165
#include"utils/fmgroids.h"
7266
#include"utils/lsyscache.h"
@@ -75,7 +69,6 @@
7569
#include"utils/ruleutils.h"
7670
#include"utils/snapmgr.h"
7771
#include"utils/syscache.h"
78-
#include"utils/tqual.h"
7972

8073

8174
/* result structure for get_rels_with_domain() */
@@ -3081,126 +3074,6 @@ domainAddConstraint(Oid domainOid, Oid domainNamespace, Oid baseTypeOid,
30813074
returnccbin;
30823075
}
30833076

3084-
/*
3085-
* GetDomainConstraints - get a list of the current constraints of domain
3086-
*
3087-
* Returns a possibly-empty list of DomainConstraintState nodes.
3088-
*
3089-
* This is called by the executor during plan startup for a CoerceToDomain
3090-
* expression node. The given constraints will be checked for each value
3091-
* passed through the node.
3092-
*
3093-
* We allow this to be called for non-domain types, in which case the result
3094-
* is always NIL.
3095-
*/
3096-
List*
3097-
GetDomainConstraints(OidtypeOid)
3098-
{
3099-
List*result=NIL;
3100-
boolnotNull= false;
3101-
RelationconRel;
3102-
3103-
conRel=heap_open(ConstraintRelationId,AccessShareLock);
3104-
3105-
for (;;)
3106-
{
3107-
HeapTupletup;
3108-
HeapTupleconTup;
3109-
Form_pg_typetypTup;
3110-
ScanKeyDatakey[1];
3111-
SysScanDescscan;
3112-
3113-
tup=SearchSysCache1(TYPEOID,ObjectIdGetDatum(typeOid));
3114-
if (!HeapTupleIsValid(tup))
3115-
elog(ERROR,"cache lookup failed for type %u",typeOid);
3116-
typTup= (Form_pg_type)GETSTRUCT(tup);
3117-
3118-
if (typTup->typtype!=TYPTYPE_DOMAIN)
3119-
{
3120-
/* Not a domain, so done */
3121-
ReleaseSysCache(tup);
3122-
break;
3123-
}
3124-
3125-
/* Test for NOT NULL Constraint */
3126-
if (typTup->typnotnull)
3127-
notNull= true;
3128-
3129-
/* Look for CHECK Constraints on this domain */
3130-
ScanKeyInit(&key[0],
3131-
Anum_pg_constraint_contypid,
3132-
BTEqualStrategyNumber,F_OIDEQ,
3133-
ObjectIdGetDatum(typeOid));
3134-
3135-
scan=systable_beginscan(conRel,ConstraintTypidIndexId, true,
3136-
NULL,1,key);
3137-
3138-
while (HeapTupleIsValid(conTup=systable_getnext(scan)))
3139-
{
3140-
Form_pg_constraintc= (Form_pg_constraint)GETSTRUCT(conTup);
3141-
Datumval;
3142-
boolisNull;
3143-
Expr*check_expr;
3144-
DomainConstraintState*r;
3145-
3146-
/* Ignore non-CHECK constraints (presently, shouldn't be any) */
3147-
if (c->contype!=CONSTRAINT_CHECK)
3148-
continue;
3149-
3150-
/*
3151-
* Not expecting conbin to be NULL, but we'll test for it anyway
3152-
*/
3153-
val=fastgetattr(conTup,Anum_pg_constraint_conbin,
3154-
conRel->rd_att,&isNull);
3155-
if (isNull)
3156-
elog(ERROR,"domain \"%s\" constraint \"%s\" has NULL conbin",
3157-
NameStr(typTup->typname),NameStr(c->conname));
3158-
3159-
check_expr= (Expr*)stringToNode(TextDatumGetCString(val));
3160-
3161-
/* ExecInitExpr assumes we've planned the expression */
3162-
check_expr=expression_planner(check_expr);
3163-
3164-
r=makeNode(DomainConstraintState);
3165-
r->constrainttype=DOM_CONSTRAINT_CHECK;
3166-
r->name=pstrdup(NameStr(c->conname));
3167-
r->check_expr=ExecInitExpr(check_expr,NULL);
3168-
3169-
/*
3170-
* use lcons() here because constraints of lower domains should be
3171-
* applied earlier.
3172-
*/
3173-
result=lcons(r,result);
3174-
}
3175-
3176-
systable_endscan(scan);
3177-
3178-
/* loop to next domain in stack */
3179-
typeOid=typTup->typbasetype;
3180-
ReleaseSysCache(tup);
3181-
}
3182-
3183-
heap_close(conRel,AccessShareLock);
3184-
3185-
/*
3186-
* Only need to add one NOT NULL check regardless of how many domains in
3187-
* the stack request it.
3188-
*/
3189-
if (notNull)
3190-
{
3191-
DomainConstraintState*r=makeNode(DomainConstraintState);
3192-
3193-
r->constrainttype=DOM_CONSTRAINT_NOTNULL;
3194-
r->name=pstrdup("NOT NULL");
3195-
r->check_expr=NULL;
3196-
3197-
/* lcons to apply the nullness check FIRST */
3198-
result=lcons(r,result);
3199-
}
3200-
3201-
returnresult;
3202-
}
3203-
32043077

32053078
/*
32063079
* Execute ALTER TYPE RENAME

‎src/backend/executor/execQual.c

Lines changed: 10 additions & 3 deletions
Original file line numberDiff line numberDiff line change
@@ -41,7 +41,6 @@
4141
#include"access/tupconvert.h"
4242
#include"catalog/objectaccess.h"
4343
#include"catalog/pg_type.h"
44-
#include"commands/typecmds.h"
4544
#include"executor/execdebug.h"
4645
#include"executor/nodeSubplan.h"
4746
#include"funcapi.h"
@@ -3929,7 +3928,10 @@ ExecEvalCoerceToDomain(CoerceToDomainState *cstate, ExprContext *econtext,
39293928
if (isDone&&*isDone==ExprEndResult)
39303929
returnresult;/* nothing to check */
39313930

3932-
foreach(l,cstate->constraints)
3931+
/* Make sure we have up-to-date constraints */
3932+
UpdateDomainConstraintRef(cstate->constraint_ref);
3933+
3934+
foreach(l,cstate->constraint_ref->constraints)
39333935
{
39343936
DomainConstraintState*con= (DomainConstraintState*)lfirst(l);
39353937

@@ -5050,7 +5052,12 @@ ExecInitExpr(Expr *node, PlanState *parent)
50505052

50515053
cstate->xprstate.evalfunc= (ExprStateEvalFunc)ExecEvalCoerceToDomain;
50525054
cstate->arg=ExecInitExpr(ctest->arg,parent);
5053-
cstate->constraints=GetDomainConstraints(ctest->resulttype);
5055+
/* We spend an extra palloc to reduce header inclusions */
5056+
cstate->constraint_ref= (DomainConstraintRef*)
5057+
palloc(sizeof(DomainConstraintRef));
5058+
InitDomainConstraintRef(ctest->resulttype,
5059+
cstate->constraint_ref,
5060+
CurrentMemoryContext);
50545061
state= (ExprState*)cstate;
50555062
}
50565063
break;

‎src/backend/utils/adt/domains.c

Lines changed: 36 additions & 42 deletions
Original file line numberDiff line numberDiff line change
@@ -12,10 +12,9 @@
1212
* The overhead required for constraint checking can be high, since examining
1313
* the catalogs to discover the constraints for a given domain is not cheap.
1414
* We have three mechanisms for minimizing this cost:
15-
*1. In a nest of domains, we flatten the checking of all the levels
16-
*into just one operation.
17-
*2. We cache the list of constraint items in the FmgrInfo struct
18-
*passed by the caller.
15+
*1. We rely on the typcache to keep up-to-date copies of the constraints.
16+
*2. In a nest of domains, we flatten the checking of all the levels
17+
*into just one operation (the typcache does this for us).
1918
*3. If there are CHECK constraints, we cache a standalone ExprContext
2019
*to evaluate them in.
2120
*
@@ -33,12 +32,12 @@
3332

3433
#include"access/htup_details.h"
3534
#include"catalog/pg_type.h"
36-
#include"commands/typecmds.h"
3735
#include"executor/executor.h"
3836
#include"lib/stringinfo.h"
3937
#include"utils/builtins.h"
4038
#include"utils/lsyscache.h"
4139
#include"utils/syscache.h"
40+
#include"utils/typcache.h"
4241

4342

4443
/*
@@ -52,8 +51,8 @@ typedef struct DomainIOData
5251
Oidtypioparam;
5352
int32typtypmod;
5453
FmgrInfoproc;
55-
/*List of constraint items to check */
56-
List*constraint_list;
54+
/*Reference to cached list of constraint items to check */
55+
DomainConstraintRefconstraint_ref;
5756
/* Context for evaluating CHECK constraints in */
5857
ExprContext*econtext;
5958
/* Memory context this cache is in */
@@ -63,16 +62,19 @@ typedef struct DomainIOData
6362

6463
/*
6564
* domain_state_setup - initialize the cache for a new domain type.
65+
*
66+
* Note: we can't re-use the same cache struct for a new domain type,
67+
* since there's no provision for releasing the DomainConstraintRef.
68+
* If a call site needs to deal with a new domain type, we just leak
69+
* the old struct for the duration of the query.
6670
*/
67-
staticvoid
68-
domain_state_setup(DomainIOData*my_extra,OiddomainType,boolbinary,
69-
MemoryContextmcxt)
71+
staticDomainIOData*
72+
domain_state_setup(OiddomainType,boolbinary,MemoryContextmcxt)
7073
{
74+
DomainIOData*my_extra;
7175
OidbaseType;
72-
MemoryContextoldcontext;
7376

74-
/* Mark cache invalid */
75-
my_extra->domain_type=InvalidOid;
77+
my_extra= (DomainIOData*)MemoryContextAlloc(mcxt,sizeof(DomainIOData));
7678

7779
/* Find out the base type */
7880
my_extra->typtypmod=-1;
@@ -95,16 +97,16 @@ domain_state_setup(DomainIOData *my_extra, Oid domainType, bool binary,
9597
fmgr_info_cxt(my_extra->typiofunc,&my_extra->proc,mcxt);
9698

9799
/* Look up constraints for domain */
98-
oldcontext=MemoryContextSwitchTo(mcxt);
99-
my_extra->constraint_list=GetDomainConstraints(domainType);
100-
MemoryContextSwitchTo(oldcontext);
100+
InitDomainConstraintRef(domainType,&my_extra->constraint_ref,mcxt);
101101

102102
/* We don't make an ExprContext until needed */
103103
my_extra->econtext=NULL;
104104
my_extra->mcxt=mcxt;
105105

106106
/* Mark cache valid */
107107
my_extra->domain_type=domainType;
108+
109+
returnmy_extra;
108110
}
109111

110112
/*
@@ -118,7 +120,10 @@ domain_check_input(Datum value, bool isnull, DomainIOData *my_extra)
118120
ExprContext*econtext=my_extra->econtext;
119121
ListCell*l;
120122

121-
foreach(l,my_extra->constraint_list)
123+
/* Make sure we have up-to-date constraints */
124+
UpdateDomainConstraintRef(&my_extra->constraint_ref);
125+
126+
foreach(l,my_extra->constraint_ref.constraints)
122127
{
123128
DomainConstraintState*con= (DomainConstraintState*)lfirst(l);
124129

@@ -215,20 +220,16 @@ domain_in(PG_FUNCTION_ARGS)
215220

216221
/*
217222
* We arrange to look up the needed info just once per series of calls,
218-
* assuming the domain type doesn't change underneath us.
223+
* assuming the domain type doesn't change underneath us (which really
224+
* shouldn't happen, but cope if it does).
219225
*/
220226
my_extra= (DomainIOData*)fcinfo->flinfo->fn_extra;
221-
if (my_extra==NULL)
227+
if (my_extra==NULL||my_extra->domain_type!=domainType)
222228
{
223-
my_extra= (DomainIOData*)MemoryContextAlloc(fcinfo->flinfo->fn_mcxt,
224-
sizeof(DomainIOData));
225-
domain_state_setup(my_extra,domainType, false,
226-
fcinfo->flinfo->fn_mcxt);
229+
my_extra=domain_state_setup(domainType, false,
230+
fcinfo->flinfo->fn_mcxt);
227231
fcinfo->flinfo->fn_extra= (void*)my_extra;
228232
}
229-
elseif (my_extra->domain_type!=domainType)
230-
domain_state_setup(my_extra,domainType, false,
231-
fcinfo->flinfo->fn_mcxt);
232233

233234
/*
234235
* Invoke the base type's typinput procedure to convert the data.
@@ -275,20 +276,16 @@ domain_recv(PG_FUNCTION_ARGS)
275276

276277
/*
277278
* We arrange to look up the needed info just once per series of calls,
278-
* assuming the domain type doesn't change underneath us.
279+
* assuming the domain type doesn't change underneath us (which really
280+
* shouldn't happen, but cope if it does).
279281
*/
280282
my_extra= (DomainIOData*)fcinfo->flinfo->fn_extra;
281-
if (my_extra==NULL)
283+
if (my_extra==NULL||my_extra->domain_type!=domainType)
282284
{
283-
my_extra= (DomainIOData*)MemoryContextAlloc(fcinfo->flinfo->fn_mcxt,
284-
sizeof(DomainIOData));
285-
domain_state_setup(my_extra,domainType, true,
286-
fcinfo->flinfo->fn_mcxt);
285+
my_extra=domain_state_setup(domainType, true,
286+
fcinfo->flinfo->fn_mcxt);
287287
fcinfo->flinfo->fn_extra= (void*)my_extra;
288288
}
289-
elseif (my_extra->domain_type!=domainType)
290-
domain_state_setup(my_extra,domainType, true,
291-
fcinfo->flinfo->fn_mcxt);
292289

293290
/*
294291
* Invoke the base type's typreceive procedure to convert the data.
@@ -326,20 +323,17 @@ domain_check(Datum value, bool isnull, Oid domainType,
326323

327324
/*
328325
* We arrange to look up the needed info just once per series of calls,
329-
* assuming the domain type doesn't change underneath us.
326+
* assuming the domain type doesn't change underneath us (which really
327+
* shouldn't happen, but cope if it does).
330328
*/
331329
if (extra)
332330
my_extra= (DomainIOData*)*extra;
333-
if (my_extra==NULL)
331+
if (my_extra==NULL||my_extra->domain_type!=domainType)
334332
{
335-
my_extra= (DomainIOData*)MemoryContextAlloc(mcxt,
336-
sizeof(DomainIOData));
337-
domain_state_setup(my_extra,domainType, true,mcxt);
333+
my_extra=domain_state_setup(domainType, true,mcxt);
338334
if (extra)
339335
*extra= (void*)my_extra;
340336
}
341-
elseif (my_extra->domain_type!=domainType)
342-
domain_state_setup(my_extra,domainType, true,mcxt);
343337

344338
/*
345339
* Do the necessary checks to ensure it's a valid domain value.

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