diff options
Diffstat (limited to 'src/backend/utils/cache/catcache.c')
| -rw-r--r-- | src/backend/utils/cache/catcache.c | 52 |
1 files changed, 48 insertions, 4 deletions
diff --git a/src/backend/utils/cache/catcache.c b/src/backend/utils/cache/catcache.c index cca0572a5dc..c467f11ac8b 100644 --- a/src/backend/utils/cache/catcache.c +++ b/src/backend/utils/cache/catcache.c @@ -734,9 +734,8 @@ InitCatCache(int id, int i; /* - * nbuckets is the number of hash buckets to use in this catcache. - * Currently we just use a hard-wired estimate of an appropriate size for - * each cache; maybe later make them dynamically resizable? + * nbuckets is the initial number of hash buckets to use in this catcache. + * It will be enlarged later if it becomes too full. * * nbuckets must be a power of two. We check this via Assert rather than * a full runtime check because the values will be coming from constant @@ -775,7 +774,8 @@ InitCatCache(int id, * * Note: we rely on zeroing to initialize all the dlist headers correctly */ - cp = (CatCache *) palloc0(sizeof(CatCache) + nbuckets * sizeof(dlist_head)); + cp = (CatCache *) palloc0(sizeof(CatCache)); + cp->cc_bucket = palloc0(nbuckets * sizeof(dlist_head)); /* * initialize the cache's relation information for the relation @@ -814,6 +814,43 @@ InitCatCache(int id, } /* + * Enlarge a catcache, doubling the number of buckets. + */ +static void +RehashCatCache(CatCache *cp) +{ + dlist_head *newbucket; + int newnbuckets; + int i; + + elog(DEBUG1, "rehashing catalog cache id %d for %s; %d tups, %d buckets", + cp->id, cp->cc_relname, cp->cc_ntup, cp->cc_nbuckets); + + /* Allocate a new, larger, hash table. */ + newnbuckets = cp->cc_nbuckets * 2; + newbucket = (dlist_head *) MemoryContextAllocZero(CacheMemoryContext, newnbuckets * sizeof(dlist_head)); + + /* Move all entries from old hash table to new. */ + for (i = 0; i < cp->cc_nbuckets; i++) + { + dlist_mutable_iter iter; + dlist_foreach_modify(iter, &cp->cc_bucket[i]) + { + CatCTup *ct = dlist_container(CatCTup, cache_elem, iter.cur); + int hashIndex = HASH_INDEX(ct->hash_value, newnbuckets); + + dlist_delete(iter.cur); + dlist_push_head(&newbucket[hashIndex], &ct->cache_elem); + } + } + + /* Switch to the new array. */ + pfree(cp->cc_bucket); + cp->cc_nbuckets = newnbuckets; + cp->cc_bucket = newbucket; +} + +/* * CatalogCacheInitializeCache * * This function does final initialization of a catcache: obtain the tuple @@ -1684,6 +1721,13 @@ CatalogCacheCreateEntry(CatCache *cache, HeapTuple ntp, cache->cc_ntup++; CacheHdr->ch_ntup++; + /* + * If the hash table has become too full, enlarge the buckets array. + * Quite arbitrarily, we enlarge when fill factor > 2. + */ + if (cache->cc_ntup > cache->cc_nbuckets * 2) + RehashCatCache(cache); + return ct; } |