From 5c7a7998a97f180d86ab368eb81a8f15a3667ef1 Mon Sep 17 00:00:00 2001
From: Howard Chu <hyc@openldap.org>
Date: Tue, 27 Nov 2001 12:36:52 +0000
Subject: [PATCH] Set the id2entry database pagesize to BDB_ID2ENTRY_PAGESIZE
to avoid overflow/fragmentation. (This is now 16K vs default 4K.) It turns
out that the entries' on-disk format is quite space-inefficient, storing 4
bytes per pointer or integer when typically >50% of those bytes are zero. Oh
well. It's about a 2:1 space increase over ldbm now, vs 4:1 before when all
the entries were overflowing the 4K pages.
---
servers/slapd/back-bdb/back-bdb.h | 9 +++++++++
servers/slapd/back-bdb/init.c | 4 +++-
2 files changed, 12 insertions(+), 1 deletion(-)
diff --git a/servers/slapd/back-bdb/back-bdb.h b/servers/slapd/back-bdb/back-bdb.h
index 9932bfb8bb..ec71844477 100644
--- a/servers/slapd/back-bdb/back-bdb.h
+++ b/servers/slapd/back-bdb/back-bdb.h
@@ -44,6 +44,15 @@ LDAP_BEGIN_DECL
#define BDB_DN2ID 1
#define BDB_NDB 2
+/* The bdb on-disk entry format is pretty space-inefficient. Average
+ * sized user entries are 3-4K each. You need at least two entries to
+ * fit into a single database page, more is better. 64K is BDB's
+ * upper bound.
+ */
+#ifndef BDB_ID2ENTRY_PAGESIZE
+#define BDB_ID2ENTRY_PAGESIZE 16384
+#endif
+
#define BDB_INDICES 128
struct bdb_db_info {
diff --git a/servers/slapd/back-bdb/init.c b/servers/slapd/back-bdb/init.c
index ac97844cbe..8e5f5b51af 100644
--- a/servers/slapd/back-bdb/init.c
+++ b/servers/slapd/back-bdb/init.c
@@ -232,10 +232,12 @@ bdb_db_open( BackendDB *be )
if( i == BDB_ID2ENTRY ) {
rc = db->bdi_db->set_bt_compare( db->bdi_db,
bdb_bt_compare );
+ rc = db->bdi_db->set_pagesize( db->bdi_db,
+ BDB_ID2ENTRY_PAGESIZE );
}
rc = db->bdi_db->open( db->bdi_db,
bdbi_databases[i].file,
- bdbi_databases[i].name,
+ /* bdbi_databases[i].name, */ NULL,
bdbi_databases[i].type,
bdbi_databases[i].flags | flags,
bdb->bi_dbenv_mode );
--
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