* Portions Copyright (c) 1994, Regents of the University of California
*
* IDENTIFICATION
- * $PostgreSQL: pgsql/src/backend/storage/freespace/freespace.c,v 1.34 2004/08/29 05:06:47 momjian Exp $
+ * $PostgreSQL: pgsql/src/backend/storage/freespace/freespace.c,v 1.35 2004/09/28 20:46:27 tgl Exp $
*
*
* NOTES:
info.hash = tag_hash;
FreeSpaceMapRelHash = ShmemInitHash("Free Space Map Hash",
- MaxFSMRelations / 10,
- MaxFSMRelations,
+ MaxFSMRelations + 1,
+ MaxFSMRelations + 1,
&info,
(HASH_ELEM | HASH_FUNCTION));
*
*
* IDENTIFICATION
- * $PostgreSQL: pgsql/src/backend/storage/ipc/shmem.c,v 1.80 2004/08/29 05:06:48 momjian Exp $
+ * $PostgreSQL: pgsql/src/backend/storage/ipc/shmem.c,v 1.81 2004/09/28 20:46:29 tgl Exp $
*
*-------------------------------------------------------------------------
*/
* shared memory hash table.
*
* We assume caller is doing some kind of synchronization
- * so that two people dont try to create/initialize the
+ * so that two people don't try to create/initialize the
* table at once.
+ *
+ * max_size is the estimated maximum number of hashtable entries. This is
+ * not a hard limit, but the access efficiency will degrade if it is
+ * exceeded substantially (since it's used to compute directory size and
+ * the hash table buckets will get overfull).
+ *
+ * init_size is the number of hashtable entries to preallocate. For a table
+ * whose maximum size is certain, this should be equal to max_size; that
+ * ensures that no run-time out-of-shared-memory failures can occur.
*/
HTAB *
ShmemInitHash(const char *name, /* table string name for shmem index */
*
*
* IDENTIFICATION
- * $PostgreSQL: pgsql/src/backend/storage/lmgr/lock.c,v 1.140 2004/09/12 18:30:50 tgl Exp $
+ * $PostgreSQL: pgsql/src/backend/storage/lmgr/lock.c,v 1.141 2004/09/28 20:46:32 tgl Exp $
*
* NOTES
* Outside modules can create a lock table and acquire/release
/* Compute init/max size to request for lock hashtables */
max_table_size = NLOCKENTS(maxBackends);
- init_table_size = max_table_size / 10;
+ init_table_size = max_table_size / 2;
/* Allocate a string for the shmem index table lookups. */
/* This is just temp space in this routine, so palloc is OK. */
*
*
* IDENTIFICATION
- * $PostgreSQL: pgsql/src/backend/utils/hash/dynahash.c,v 1.53 2004/08/29 05:06:50 momjian Exp $
+ * $PostgreSQL: pgsql/src/backend/utils/hash/dynahash.c,v 1.54 2004/09/28 20:46:34 tgl Exp $
*
*-------------------------------------------------------------------------
*/
*/
static void *DynaHashAlloc(Size size);
static HASHSEGMENT seg_alloc(HTAB *hashp);
-static bool element_alloc(HTAB *hashp);
+static bool element_alloc(HTAB *hashp, int nelem);
static bool dir_realloc(HTAB *hashp);
static bool expand_table(HTAB *hashp);
static bool hdefault(HTAB *hashp);
CurrentDynaHashCxt = hashp->hcxt;
}
+ /* Build the hash directory structure */
if (!init_htab(hashp, nelem))
{
hash_destroy(hashp);
return NULL;
}
+
+ /*
+ * For a shared hash table, preallocate the requested number of elements.
+ * This reduces problems with run-time out-of-shared-memory conditions.
+ */
+ if (flags & HASH_SHARED_MEM)
+ {
+ if (!element_alloc(hashp, (int) nelem))
+ {
+ hash_destroy(hashp);
+ return NULL;
+ }
+ }
+
return hashp;
}
if (currBucket == NULL)
{
/* no free elements. allocate another chunk of buckets */
- if (!element_alloc(hashp))
+ if (!element_alloc(hashp, HASHELEMENT_ALLOC_INCR))
return NULL; /* out of memory */
currBucket = hctl->freeList;
Assert(currBucket != NULL);
* allocate some new elements and link them into the free list
*/
static bool
-element_alloc(HTAB *hashp)
+element_alloc(HTAB *hashp, int nelem)
{
HASHHDR *hctl = hashp->hctl;
Size elementSize;
CurrentDynaHashCxt = hashp->hcxt;
tmpElement = (HASHELEMENT *)
- hashp->alloc(HASHELEMENT_ALLOC_INCR * elementSize);
+ hashp->alloc(nelem * elementSize);
if (!tmpElement)
return false;
/* link all the new entries into the freelist */
- for (i = 0; i < HASHELEMENT_ALLOC_INCR; i++)
+ for (i = 0; i < nelem; i++)
{
tmpElement->link = hctl->freeList;
hctl->freeList = tmpElement;
* Portions Copyright (c) 1996-2004, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
- * $PostgreSQL: pgsql/src/include/storage/shmem.h,v 1.42 2004/08/29 04:13:10 momjian Exp $
+ * $PostgreSQL: pgsql/src/include/storage/shmem.h,v 1.43 2004/09/28 20:46:35 tgl Exp $
*
*-------------------------------------------------------------------------
*/
/* size constants for the shmem index table */
/* max size of data structure string name */
#define SHMEM_INDEX_KEYSIZE (48)
- /* maximum size of the shmem index table */
-#define SHMEM_INDEX_SIZE (100)
+ /* max size of the shmem index table (not a hard limit) */
+#define SHMEM_INDEX_SIZE (32)
/* this is a hash bucket in the shmem index table */
typedef struct
* Portions Copyright (c) 1996-2004, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
- * $PostgreSQL: pgsql/src/include/utils/hsearch.h,v 1.32 2004/08/29 05:06:59 momjian Exp $
+ * $PostgreSQL: pgsql/src/include/utils/hsearch.h,v 1.33 2004/09/28 20:46:37 tgl Exp $
*
*-------------------------------------------------------------------------
*/
#define HASH_FFACTOR 0x008 /* Set fill factor */
#define HASH_FUNCTION 0x010 /* Set user defined hash function */
#define HASH_ELEM 0x020 /* Set key/entry size */
-#define HASH_SHARED_MEM 0x040 /* Set shared mem const */
+#define HASH_SHARED_MEM 0x040 /* Hashtable is in shared memory */
#define HASH_ATTACH 0x080 /* Do not initialize hctl */
#define HASH_ALLOC 0x100 /* Set memory allocator */
#define HASH_CONTEXT 0x200 /* Set explicit memory context */
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