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authorMarko Mäkelä <marko.makela@mariadb.com>2019-10-23 17:43:31 +0300
committerMarko Mäkelä <marko.makela@mariadb.com>2019-10-23 17:43:31 +0300
commit88cdfc5c7d4764e5267c87eadeb8c3f95faa73d0 (patch)
tree98c65ca953c1c2a6475c95c9cd2eb6c31ddb77f2 /extra
parent18a44b4b4b2fdf4aefc9ae2712678fc54ae42dfc (diff)
downloadmariadb-git-88cdfc5c7d4764e5267c87eadeb8c3f95faa73d0.tar.gz
MDEV-20487 Set innodb_adaptive_hash_index=OFF by default
Based on the performance testing that was conducted in MDEV-17492, the InnoDB adaptive hash index could only help performance in specific, almost-read-only workloads. It could slow down all kinds of workloads (especially DROP TABLE, TRUNCATE TABLE, ALTER TABLE, or DROP INDEX operations), and it can become corrupted, causing crashes (such as MDEV-18815, MDEV-20203) and possibly data corruption. Furthermore, the adaptive hash index consumes space from the InnoDB buffer pool, which could hurt performance when the working set would almost fit in the buffer pool. Given all this, it is best to disable the adaptive hash index by default.
Diffstat (limited to 'extra')
-rw-r--r--extra/mariabackup/xtrabackup.cc5
1 files changed, 2 insertions, 3 deletions
diff --git a/extra/mariabackup/xtrabackup.cc b/extra/mariabackup/xtrabackup.cc
index 7924791f0e9..0046d62d25e 100644
--- a/extra/mariabackup/xtrabackup.cc
+++ b/extra/mariabackup/xtrabackup.cc
@@ -1239,11 +1239,10 @@ struct my_option xb_server_options[] =
GET_STR, OPT_ARG, 0, 0, 0, 0, 0, 0},
#ifdef BTR_CUR_HASH_ADAPT
{"innodb_adaptive_hash_index", OPT_INNODB_ADAPTIVE_HASH_INDEX,
- "Enable InnoDB adaptive hash index (enabled by default). "
- "Disable with --skip-innodb-adaptive-hash-index.",
+ "Enable InnoDB adaptive hash index (disabled by default).",
&btr_search_enabled,
&btr_search_enabled,
- 0, GET_BOOL, NO_ARG, 1, 0, 0, 0, 0, 0},
+ 0, GET_BOOL, NO_ARG, 0, 0, 0, 0, 0, 0},
#endif /* BTR_CUR_HASH_ADAPT */
{"innodb_autoextend_increment", OPT_INNODB_AUTOEXTEND_INCREMENT,
"Data file autoextend increment in megabytes",