Variables on FromDual GmbH

MariaDB configuration analysis

oli.sennhauser@fromdual.com (Oli Sennhauser) — Tue, 30 Mar 2021 10:38:06 +0000

If we do customers database configuration analysis we check on one side if the most important MariaDB server system variables (innodb_buffer_pool_size, …) are set appropriately but also if some MariaDB server system variables are configured completely wrong.

MariaDB MaxScale Configuration Variables

oli.sennhauser@fromdual.com (Oli Sennhauser) — Wed, 04 Nov 2020 22:49:39 +0000

Global Options

Variable	Versions					Values	Default	Unit	Comment
threads	1.4		2.3	2.4	2.5	{ <n> \| auto }	1	thread
thread_stack_size		2.2				<n>			Ignored and deprecated in 2.3
rebalance_period					2.5	<n>	0	second
rebalance_threshold					2.5	<n>	20	delta load
rebalance_window					2.5	<n>	10	second
auth_connect_timeout	1.4	2.2	2.3	2.4		<n>	3	second
auth_read_timeout	1.4	2.2	2.3	2.4		<n>	1	second	Deprecated in 2.5
auth_write_timeout	1.4	2.2	2.3	2.4		<n>	2	second	Deprecated in 2.5
query_retries			2.3	2.4	2.5	<n>	1	time	Added in 2.1.10, disabled by default until 2.3.0
query_retry_timeout			2.3	2.4	2.5		5
passive			2.3	2.4	2.5		false
ms_timestamp	1.4		2.3	2.4	2.5	{ 0 \| 1 }	0	-
skip_permission_checks			2.3	2.4	2.5	{ 0 \| 1 }	0
syslog	1.4		2.3	2.4	2.5	{ 0 \| 1 }	1	-
maxlog	1.4		2.3	2.4	2.5	{ 0 \| 1 }	1	-
log_to_shm	1.4					{ 0 \| 1 }	0	-	Deprecated and ignored in 2.3.0 and newer
log_warning	1.4		2.3	2.4	2.5	{ 0 \| 1 }	1	-
log_notice	1.4		2.3	2.4	2.5	{ 0 \| 1 }	1	-
log_info	1.4		2.3	2.4	2.5	{ 0 \| 1 }	0	-
log_debug	1.4		2.3	2.4	2.5	{ 0 \| 1 }	0	-
log_warn_super_user					2.5		false
log_messages									Deprecated, use log_notice instead
log_trace									Deprecated, use log_info instead
log_augmentation	1.4		2.3	2.4	2.5	{ 0 \| 1 }	0	-
log_throttling			2.3	2.4	2.5	{ <n>, <n>, <n> }	10, 1000, 10000	time, millisecond, millisecond
logdir	1.4		2.3	2.4	2.5	<dirpath>	/tmp/	-
datadir	1.4		2.3	2.4	2.5	<dirpath>	/home/user/maxscale_data/	-
libdir	1.4		2.3	2.4	2.5	<dirpath>	/home/user/lib64/	-
cachedir	1.4		2.3	2.4	2.5	<dirpath>	/tmp/maxscale_cache/	-
piddir	1.4		2.3	2.4	2.5	<dirpath>	/tmp/maxscale_cache/	-
execdir	1.4		2.3	2.4	2.5	<dirpath>	/usr/local/bin/	-
connector_plugindir			2.3	2.4	2.5	<dirpath>	/usr/lib/plugin/
persistdir			2.3	2.4	2.5	<dirpath>	/var/lib/maxscale/maxscale.cnf.d/
module_configdir			2.3	2.4	2.5	<dirpath>	/var/lib/maxscale/
language	1.4		2.3	2.4	2.5	<dirpath>	/home/user/lang/	-
query_classifier			2.3	2.4	2.5	<classifier>	qc_sqlite
query_classifier_cache_size			2.3	2.4	2.5	<n>	15% of system Memory	byte
query_classifier_args			2.3	2.4	2.5
substitute_variables			2.3	2.4	2.5	{ true \| false }	false
sql_mode			2.3	2.4	2.5	{ default \| oracle }	default
local_address			2.3	2.4	2.5	<IP address>	*
users_refresh_time			2.3	2.4	2.5	<n>	30	second
user_refresh_interval				2.4	2.5	<n>	0	second
retain_last_statements			2.3	2.4	2.5	<n>	0	statement
dump_last_statements			2.3	2.4	2.5	{ on_error \| on_close \| never }	never	-
session_trace			2.3	2.4	2.5	<n>	0	statement
writeq_high_water			2.3	2.4	2.5
writeq_low_water			2.3	2.4	2.5
load_persisted_configs			2.3	2.4	2.5	{ 0 \| 1 }	1
max_auth_errors_until_block				2.4	2.5	<n>	10
debug					2.5
admin_host			2.3	2.4	2.5	<IP address>	127.0.0.1
admin_port			2.3	2.4	2.5	<n>	8989
admin_auth			2.3	2.4	2.5		1
admin_ssl_key			2.3	2.4	2.5
admin_ssl_cert			2.3	2.4	2.5
admin_ssl_ca_cert			2.3	2.4	2.5
admin_enabled			2.3	2.4	2.5	{ 0 \| 1 }
admin_gui					2.5		1
admin_secure_gui					2.5
admin_log_auth_failures				2.4	2.5	{ 0 \| 1 }	1
admin_pam_readwrite_service				2.4	2.5
admin_pam_readonly_service				2.4	2.5

Service Options

Variable	Versions					Values	Default	Unit	Comment
type	1.4		2.3	2.4	2.5	service		-
router	1.4		2.3	2.4	2.5	{ readconnroute \| readwritesplit \| schemarouter \| binlogrouter }		-
router_option	1.4		2.3	2.4	2.5	{ slave \| master,slave }		-
filters	1.4		2.3	2.4	2.5	{ counter \| QLA }		-
targets					2.5	{ server \| service, ... }
servers	1.4		2.3	2.4	2.5	{ <server1>, <server2>, ... }		-
cluster				2.4	2.5	<name>
user	1.4		2.3	2.4	2.5	{ <username> }		-
passwd	1.4		2.3	2.4	2.5	{ <password> }		-
enable_root_user	1.4		2.3	2.4	2.5	{ 0 \| 1 }	0	-
localhost_match_wildcard_host	1.4		2.3	2.4		{ 0 \| 1 }	0		Deprecated and ignored.
version_string	1.4		2.3	2.4	2.5	<string>	5.5.5-10.0.0 MaxScale <MaxScale version>
weightby	1.4		2.3	2.4		<server_weight>			Deprecated in 2.3 and removed in 2.5, use rank instead
auth_all_servers	1.4		2.3	2.4	2.5	{ 0 \| 1 }	0
strip_db_esc	1.4		2.3	2.4	2.5	{ 0 \| 1 }	0
optimize_wildcard	1.4			2.4		{ 0 \| 1 }	0
retry_on_failure	1.4		2.3			{ 0 \| 1 }	1		Ignored by 2.4 and removed in the future.
log_auth_warnings	1.4		2.3	2.4	2.5	{ 0 \| 1 }	0
connection_timeout	1.4		2.3	2.4	2.5	<n>		second
max_connections			2.3	2.4	2.5	<n>		connection
max_retry_interval		2.2	2.3	2.4		<n>	3600	second
session_track_trx_state			2.3	2.4	2.5		false		Only supported by MariaDB 10.3 and newer
retain_last_statements			2.3	2.4	2.5
connection_keepalive					2.5	<n>	300
net_write_timeout				2.4	2.5		0	second

Routing Modules

ReadConnRoute

For (weighted) load balancing.

MySQL and MariaDB variables inflation

oli.sennhauser@fromdual.com (Oli Sennhauser) — Mon, 12 Dec 2016 21:43:42 +0000

MySQL is well known and widely spread because of its philosophy of Keep it Simple (KISS).

InnoDB Buffer Pool Instances is too small

oli.sennhauser@fromdual.com (Oli Sennhauser) — Thu, 16 Jul 2015 20:09:36 +0000

If you are using MariaDB/MySQL 5.5 and newer you should use several InnoDB Buffer Pool Instances for performance reasons.
Some rules to size InnoDB Buffer Pool instances are:

Binlog format MIXED with filtering

oli.sennhauser@fromdual.com (Oli Sennhauser) — Wed, 15 Jul 2015 06:11:36 +0000

Binlog format MIXED changes the binary log format (ROW or STATEMENT) depending on the queries (deterministic or not). This makes it impossible to define 100% correctly working binary log filter rules.

Flush time is set

oli.sennhauser@fromdual.com (Oli Sennhauser) — Wed, 15 Jul 2015 06:10:36 +0000

If the variable flush_time is set to a non-zero value, all tables are closed (and flushed) every flush_time seconds to disk. This can cause unnecessary and high I/O spikes.

Table open cache too small

oli.sennhauser@fromdual.com (Oli Sennhauser) — Wed, 15 Jul 2015 06:04:36 +0000

The Table Open Cache (table_open_cache or old name table_cache) is a cache to store file handles for all threads. The actual value of cache entries can be seen with the global status of open tables (Open_tables).
Increasing table_open_cache increases the number of file descriptors (open_files_limit) that MySQL requires.
You can check whether you need to increase the Table Open Cache by checking Open_tables and Opened_tables. If the value of Opened_tables is large and you do not use FLUSH TABLES often (which just forces all tables to be closed and reopened), then you should increase the value of the table_open_cache variable.

InnoDB Flush Method has changed

oli.sennhauser@fromdual.com (Oli Sennhauser) — Wed, 01 Jul 2015 10:34:36 +0000

The InnoDB Flush Method has changed. This can have an impact on InnoDB write Performance.

InnoDB variables and status explained

oli.sennhauser@fromdual.com (Oli Sennhauser) — Mon, 02 Jul 2012 17:07:32 +0000

InnoDB Buffer Pool

The InnoDB Buffer Pool is the memory area where the InnoDB Storage Engine caches its data and index blocks. Each InnoDB data and index block has a size of Innodb_page_size (16384 byte = 16 kbyte). The InnoDB Buffer Pool is configured in bytes with the innodb_buffer_pool_size variable. On a dedicated system the InnoDB Buffer Pool can be configured up to 80% of the systems physical RAM (free).