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Commita86c61c

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committed
Optimize SearchPathCache by saving the last entry.
Repeated lookups are common, so it's worth it to check the last entrybefore doing another hash lookup.Discussion:https://postgr.es/m/04c8592dbd694e4114a3ed87139a7a04e4363030.camel%40j-davis.com
1 parentb14b1eb commita86c61c

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1 file changed

+57
-31
lines changed

1 file changed

+57
-31
lines changed

‎src/backend/catalog/namespace.c

Lines changed: 57 additions & 31 deletions
Original file line numberDiff line numberDiff line change
@@ -241,7 +241,8 @@ static bool MatchNamedCall(HeapTuple proctup, int nargs, List *argnames,
241241
*
242242
* The search path cache is based on a wrapper around a simplehash hash table
243243
* (nsphash, defined below). The spcache wrapper deals with OOM while trying
244-
* to initialize a key, and also offers a more convenient API.
244+
* to initialize a key, optimizes repeated lookups of the same key, and also
245+
* offers a more convenient API.
245246
*/
246247

247248
staticinlineuint32
@@ -281,6 +282,7 @@ spcachekey_equal(SearchPathCacheKey a, SearchPathCacheKey b)
281282
#defineSPCACHE_RESET_THRESHOLD256
282283

283284
staticnsphash_hash*SearchPathCache=NULL;
285+
staticSearchPathCacheEntry*LastSearchPathCacheEntry=NULL;
284286

285287
/*
286288
* Create or reset search_path cache as necessary.
@@ -295,6 +297,7 @@ spcache_init(void)
295297
return;
296298

297299
MemoryContextReset(SearchPathCacheContext);
300+
LastSearchPathCacheEntry=NULL;
298301
/* arbitrary initial starting size of 16 elements */
299302
SearchPathCache=nsphash_create(SearchPathCacheContext,16,NULL);
300303
searchPathCacheValid= true;
@@ -307,12 +310,25 @@ spcache_init(void)
307310
staticSearchPathCacheEntry*
308311
spcache_lookup(constchar*searchPath,Oidroleid)
309312
{
310-
SearchPathCacheKeycachekey= {
311-
.searchPath=searchPath,
312-
.roleid=roleid
313-
};
313+
if (LastSearchPathCacheEntry&&
314+
LastSearchPathCacheEntry->key.roleid==roleid&&
315+
strcmp(LastSearchPathCacheEntry->key.searchPath,searchPath)==0)
316+
{
317+
returnLastSearchPathCacheEntry;
318+
}
319+
else
320+
{
321+
SearchPathCacheEntry*entry;
322+
SearchPathCacheKeycachekey= {
323+
.searchPath=searchPath,
324+
.roleid=roleid
325+
};
326+
327+
entry=nsphash_lookup(SearchPathCache,cachekey);
314328

315-
returnnsphash_lookup(SearchPathCache,cachekey);
329+
LastSearchPathCacheEntry=entry;
330+
returnentry;
331+
}
316332
}
317333

318334
/*
@@ -324,35 +340,45 @@ spcache_lookup(const char *searchPath, Oid roleid)
324340
staticSearchPathCacheEntry*
325341
spcache_insert(constchar*searchPath,Oidroleid)
326342
{
327-
SearchPathCacheEntry*entry;
328-
SearchPathCacheKeycachekey= {
329-
.searchPath=searchPath,
330-
.roleid=roleid
331-
};
332-
333-
/*
334-
* searchPath is not saved in SearchPathCacheContext. First perform a
335-
* lookup, and copy searchPath only if we need to create a new entry.
336-
*/
337-
entry=nsphash_lookup(SearchPathCache,cachekey);
338-
339-
if (!entry)
343+
if (LastSearchPathCacheEntry&&
344+
LastSearchPathCacheEntry->key.roleid==roleid&&
345+
strcmp(LastSearchPathCacheEntry->key.searchPath,searchPath)==0)
340346
{
341-
boolfound;
347+
returnLastSearchPathCacheEntry;
348+
}
349+
else
350+
{
351+
SearchPathCacheEntry*entry;
352+
SearchPathCacheKeycachekey= {
353+
.searchPath=searchPath,
354+
.roleid=roleid
355+
};
342356

343-
cachekey.searchPath=MemoryContextStrdup(SearchPathCacheContext,searchPath);
344-
entry=nsphash_insert(SearchPathCache,cachekey,&found);
345-
Assert(!found);
357+
/*
358+
* searchPath is not saved in SearchPathCacheContext. First perform a
359+
* lookup, and copy searchPath only if we need to create a new entry.
360+
*/
361+
entry=nsphash_lookup(SearchPathCache,cachekey);
346362

347-
entry->oidlist=NIL;
348-
entry->finalPath=NIL;
349-
entry->firstNS=InvalidOid;
350-
entry->temp_missing= false;
351-
entry->forceRecompute= false;
352-
/* do not touch entry->status, used by simplehash */
353-
}
363+
if (!entry)
364+
{
365+
boolfound;
366+
367+
cachekey.searchPath=MemoryContextStrdup(SearchPathCacheContext,searchPath);
368+
entry=nsphash_insert(SearchPathCache,cachekey,&found);
369+
Assert(!found);
370+
371+
entry->oidlist=NIL;
372+
entry->finalPath=NIL;
373+
entry->firstNS=InvalidOid;
374+
entry->temp_missing= false;
375+
entry->forceRecompute= false;
376+
/* do not touch entry->status, used by simplehash */
377+
}
354378

355-
returnentry;
379+
LastSearchPathCacheEntry=entry;
380+
returnentry;
381+
}
356382
}
357383

358384
/*

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