proxysql global_variables 翻譯

• at runtime, using the admin interface (preferred)
• • at startup, using the dedicated section in the configuration file

Also, there are 2 types of global variables, depending on which part of ProxySQL they control:

• admin variables, which control the behaviour of the admin interface. Their names begin with the token "admin-"
• mysql variables, which control the MySQL functionality of the proxy. Their names begin with the token "mysql-"

To change the value of a global variable either use an UPDATE statement:

UPDATE global_variables SET variable_value=1900 WHERE variable_name='admin-refresh_interval'; 

or the shorter SET statement, similar to MySQL's:

SET admin-refresh_interval = 1700;
SET admin-version = '1.1.1beta8'; 

Next, we're going to explain each type of variable in detail.

Admin Variables

admin-admin_credentials

Default value: false

admin-refresh_interval 統計狀態的時間間隔 預設兩秒 不修改

The refresh interval (in microseconds) for updates to the query rules statistics and commands counters statistics. Be careful about tweaking this to a value that is:

• too low, because it might affect the overall performance of the proxy
• too high, because it might affect the correctness of the results

Default value: 2000 (microseconds)

admin-telnet_admin_ifaces

Not currently used (planned usage in a future version).

admin-telnet_stats_ifaces

Not currently used (planned usage in a future version).

admin-version

This variable displays ProxySQL version. This variable is read only.

MySQL Variables

mysql-client_found_rows

When set to true, client flag CLIENT_FOUND_ROWS is set when connecting to MySQL backends.

Default value: true

mysql-commands_stats

Enable per-command MySQL query statistics. A command is a type of SQL query that is being executed. Some examples are: SELECT, INSERT or ALTER TABLE. See the stats_mysql_commands_counters section in the admin tables documentation in order to see more details about what kind of statistics are gathered.

Default value: true

mysql-connect_retries_delay

The delay (in milliseconds) before trying to reconnect after a failed attempt to a backend MySQL server. Failed attempts can take place due to numerous reasons: too busy, timed out for the current attempt, etc. This will be retried for mysql-connect_retries_on_failure times.

Default value: 1 (milliseconds)

Be careful about tweaking this parameter - a value that is too high can significantly increase the latency which with an unresponsive 反應遲鈍的 hostgroup is reported to the MySQL client.

Default value: 5 (reconnect times)

mysql-connect_timeout_server

The timeout for a single attempt at connecting to a backend server from the proxy. If this fails, according to the other parameters, the attempt will be retried until too many errors per second are generated (and the server is automatically shunned) or until the final cut-off is reached and an error is returned to the client (see mysql-connect_timeout_server_max).

Default value: 1000 (miliseconds, the equivalent of 1 second)

mysql-connect_timeout_server_max

The timeout for connecting to a backend server from the proxy. When this timeout is reached, an error is returned to the client with code #28000 and the message "Max connect timeout reached while reaching hostgroup...".

Default value: 10000 (miliseconds, the equivalent of 10 seconds)

mysql-connection_max_age_ms

When mysql-connection_max_age_ms is set to a value greater than 0, inactive connections in the connection pool (therefore not currently used by any session) are closed if they were created more than mysql-connection_max_age_ms milliseconds ago. By default, connections aren't closed based on their age.

Default value: 0 (milliseconds)

mysql-default_charset

The default server charset to be used in the communication with the MySQL clients. Note that this is the defult for client connections, not for backend connections.

Default value: utf8

mysql-default_max_latency_ms

ProxySQL uses a mechanism to automatically ignore hosts if their latency is excessive. Note that hosts are not disabled, but only ignored: in other words, ProxySQL will prefer hosts with a smaller latency. It is possible to configure the maximum latency for each backend from mysql_users table, column max_latency_ms. If mysql_users.max_latency_ms is 0, the default valuemysql-default_max_latency_ms applies.

Default: 1000 (millisecond)

mysql-default_query_delay

Simple throttling mechanism for queries to the backends. Setting this variable to a non-zero value (in miliseconds) will delay the execution of all queries, globally. There is a more fine-grained throttling mechanism in the admin table mysql_query_rules, where for each rule there can be one delay that is applied to all queries matching the rule. That extra delay is added on top of the default, global one.

Default value: 0 (miliseconds)

mysql-default_query_timeout

Mechanism for specifying the maximal duration of queries to the backend MySQL servers until ProxySQL should return an error to the MySQL client. Whenever ProxySQL detects that a query has timed out, it will spawn 引起 a separate thread that runs a KILL query against the specific MySQL backend in order to stop the query from running in the backend. Because the query is killed, an error will be returned to the MySQL client.

Default value: 86400000 (miliseconds - the equivalent of 1 day = 24 hours)

mysql-default_reconnect

Not used for now.

mysql-default_schema

The default schema to be used for incoming MySQL client connections which do not specify a schema name. This is required because ProxySQL doesn't allow connection without a schema.

Default value: information_schema

ProxySQL tracks the status of autocommit as specified by the client, and ensures that autocommit is set correct on backend connections. This implementation is problematic 有問題的 if a client starts a transaction using autocommit, and read/write split is implemented via query rules. In fact, if a read is sent to a slave and ProxySQL sets autocommit=0 on slave, this will result in 2 transactions (one on master and one on slave). To prevent this to happen, if mysql-enforce_autocommit_on_reads=false (the default), ProxySQL won't change the value of autocommit on backend connections for SELECT stataments.

Default value: false

If this variable is set, ProxySQL will log all traffic to the specified filename. Note that the log file is not a text file, but a binary log with encodided traffic.

Default value: empty string, not set

mysql-eventslog_filesize proxusql日誌檔案的大小限制

This variable specifies the maximum size of files created by ProxySQL logger as specified in mysql-eventslog_filename. When the maximum size is reached, the file is rotated.

Default value: 104857600 (100MB)

mysql-free_connections_pct proxysql提供連線池到後臺的mysql 這個引數控制其中空閒的查詢的佔比

ProxySQL uses a connection pool to connect to backend servers. As part of this, it sometimes decides to keep some connections open and ready to use for future queries. It does this by pinging them once in a while. This variable controls the percentage of open idle connections from the total maximal number of connections open to that server.

A connection is idle if it hasn't used since the last round of pings. The time interval between two such rounds of pings for idle connections is controlled by the variable mysql-processing_idles.

Default value: 10 (percent)

mysql-have_compress

Currently unused.

mysql-interfaces

The TCP interfaces on which ProxySQL should listen for incoming MySQL traffic. As is obvious from the default value, this also supports UNIX sockets for faster local traffic.

Default value: 0.0.0.0:6033;/tmp/proxysql.sock

mysql-long_query_time

Threshold for counting queries passing through the proxy as 'slow'. The total number of slow queries can be found in thestats_mysql_global table, in the variable named Slow_queries (each row in that table represents one variable).

Default value: 1000 (ms)

mysql-max_connections

The maximal number of TCP connections that the proxy can handle. After this number is reached, new connections will be rejected with the #HY000 error, and the error message Too many connections.

Default value: 10000 (connections)

mysql-max_transaction_time

mysql-monitor_connect_interval

The interval at which the Monitor module of the proxy will try to connect to all the MySQL servers in order to check whether they are available or not.

Default value: 120000 (miliseconds - the equivalent of 2 minutes) 2分鐘對mysql servers 做一次檢測

mysql-monitor_connect_timeout

Default value: 200 (miliseconds)

mysql-monitor_enabled

It enables or disables MySQL Monitor.

Defaut value: true

mysql-monitor_history

The duration for which the events for the checks made by the Monitor module are kept. Such events include connecting to backend servers (to check for connectivity issues), querying them with a simple query (in order to check that they are running correctly) or checking their replication lag. These logs are kept in the following admin tables:

• mysql_server_connect_log
• mysql_server_ping_log
• mysql_server_replication_lag_log

Default value: 600000 (miliseconds - the equivalent of 100 seconds)

mysql-monitor_username, mysql-monitor_password

The (username, password) combination with which the Monitor module will connect to the backend servers in order to check their health. Note that ProxySQL does not make any automated decisions based on these checks, but the data can be used in external scripts.

It is also very important to note that mysql-monitor_username must not be a user in mysql_users table. Although, ProxySQL does not enforce this restriction.

Default values: monitor / monitor

mysql-monitor_ping_interval

The interval at which the Monitor module should ping the backend servers by using the mysql_ping API.

Default value: 60000 (miliseconds, the equivalent of 1 minute)

mysql-monitor_ping_timeout

Currently unused.

Default value: 100 (miliseconds)

mysql-monitor_query_interval

Currently unused. Will be used by the Monitor module in order to collect data about the global status of the backend servers.

Default value: 60000 (miliseconds, the equivalent of 1 minute)

mysql-monitor_query_status

Currently unused. Will be used by the Monitor module in order to collect data about the global status of the backend servers.

Default value: SELECT * FROM INFORMATION_SCHEMA.GLOBAL_STATUS

mysql-monitor_query_timeout

Currently unused. Will be used by the Monitor module in order to collect data about the global status of the backend servers.

Default value: 100 (miliseconds)

mysql-monitor_query_variables

Currently unused. Will be used by the Monitor module in order to collect data about the global status of the backend servers.

Default value: SELECT * FROM INFORMATION_SCHEMA.GLOBAL_VARIABLES

mysql-monitor_replication_lag_interval

The interval at which the proxy should connect to the backend servers in order to monitor the replication lag between those that are slaves and their masters. Slaves can be temporarily shunned if the replication lag is too large. This setting is controlled by themysql_servers.max_replication_lag column in the admin interface, at a per-hostgroup level.

Default value: 10000 (miliseconds, the equivalent of 10 seconds)

mysql-monitor_replication_lag_timeout

Currently unused.

Default value: 1000 (miliseconds)

mysql-monitor_timer_cached

This variable controls whether ProxySQL should use a cached (and less accurate) value of wall clock time, or not. The actual API used for this is described here.

Default value: true

mysql-ping_interval_server_msec

The interval at which the proxy should ping backend connections in order to maintain them alive, even though there is no outgoing traffic. The purpose here is to keep some connections alive in order to reduce the latency of new queries towards a less frequently used destination backend server.

Default value: 10000 (miliseconds, the equivalent of 10 seconds)

mysql-ping_timeout_server

The proxy internally pings the connections it has opened in order to keep them alive. This elliminates 消除 the cost of opening a new connection towards a hostgroup when a query needs to be routed, at the cost of additional memory footprint inside the proxy and some extra traffic. This is the timeout allowed for those pings to succeed.

Default value: 200 (miliseconds)

mysql-poll_timeout

The minimal timeout used by the proxy in order to detect incoming/outgoing traffic via the poll() system call. If the proxy determines that it should stick to a higher timeout because of its internal computations, it will use that one, but it will never use a value less than this one.

Default value: 2000 (miliseconds, the equivalent of 2 seconds)

mysql-poll_timeout_on_failure

The timeout used in order to detect incoming/outgoing traffic after a connection error has occured. The proxy automatically tweaks its timeout to a lower value in such an event in order to be able to quickly respond with a valid connection.

Default value: 100 (miliseconds)

mysql-query_digests

When this variable is set to true, the proxy analyzes the queries passing through it and divides them into classes of queries having different values for the same parameters. It computes a couple of metrics for these classes of queries, all found in thestats_mysql_query_digest table. For more details, please refer to the admin tables documentation.

Default value: true (query digests are enabled)

mysql-server_capabilities

The bitmask 位掩碼 of MySQL capabilities (encoded as bits) with which the proxy will respond to clients connecting to it. This is useful in order to prevent certain features from being used. The default capabilities are:

server_capabilities = CLIENT_FOUND_ROWS | CLIENT_PROTOCOL_41 | CLIENT_IGNORE_SIGPIPE | CLIENT_TRANSACTIONS | CLIENT_SECURE_CONNECTION | CLIENT_CONNECT_WITH_DB | CLIENT_SSL;

More details about server capabilities in the official documentation.

Default value: 47626

mysql-server_version

The server version with which the proxy will respond to the clients. Note that regardless of the versions of the backend servers, the proxy will respond with this.

Default value: 5.5.30

mysql-servers_stats

Currently unused. Will be removed in a future version.

Default value: true

mysql-session_debug

Currently unused. Will be removed in a future version.

Default value: true

mysql-sessions_sort

Sessions are conversations 對話 between a MySQL client and a backend server in the proxy. Sessions are generally processed in a stable order but in certain scenarios (like using a transaction workload, which makes sessions bind to certain MySQL connections from the pool), processing them in the same order leads to starvation 飢餓.

This variable controls whether sessions should be processed in the order of waiting time, in order to have a more balanced distribution of traffic among sessions.

Default value: true

mysql-shun_on_failures

The number of connection errors tolerated to the same server within an interval of 1 second until it is automatically shunned temporarily. For now, this can not be disabled by setting it to a special value, so if you want to do that, you can increase it to a very large value.

Default value: 5

mysql-shun_recovery_time

A backend server that has been automatically shunned will be recovered after at least this amount of time. Note that there is no actual hard guarantee of the exact timing, but in practice it shouldn't exceed this value by more than a couple of seconds.

Default value: 10 (seconds)

mysql-stacksize

The stack size to be used with the background threads that the proxy uses to handle MySQL traffic and connect to the backends. Note that changing this value has no effect at runtime, if you need to change it you have to restart the proxy.

Default value: 1048576 (bytes, the equivalent of 1 MB)

mysql-threads

The number of background threads that ProxySQL uses in order to process MySQL traffic. Note that there are other "administrative" threads on top of these, such as:

• the admin interface thread
• the monitoring module threads that interact with the backend servers (one for monitoring connectivity, one for pinging the servers and one for monitoring the replication lag)
• occasional temporary threads created in order to kill long running queries that have become unresponsive
• background threads used by the libmariadbclient library in order to make certain interactions with MySQL servers async

Note that changing this value has no effect at runtime, if you need to change it you have to restart the proxy.

Default value: 4 (background threads to process MySQL traffic)

mysql-threshold_query_length

The maximal size of an incoming SQL query to the proxy that will mark the background MySQL connection as non-reusable. This will force the proxy to open a new connection to the backend server, in order to make sure that the memory footprint of the server stays within reasonable limits.

More details about it here: https://dev.mysql.com/doc/refman/5.6/en/memory-use.html

Relevant quote from the mysqld documentation: "The connection buffer and result buffer each begin with a size equal to net_buffer_length bytes, but are dynamically enlarged up to max_allowed_packet bytes as needed. The result buffer shrinks to net_buffer_length bytes after each SQL statement."

Default value: 524288 (bytes, the equivalent of 0.5 MB)

mysql-threshold_resultset_size

If a resultset returned by a backend server is bigger than this, proxysql will start sending the result to the MySQL client that was requesting the result in order to limit its memory footprint.

Default value: 4194304 (bytes, the equivalent of 4 MB)

mysql-wait_timeout

If a proxy session (which is a conversation between a MySQL client and a backend MySQL server) has been idle for more than this threshold, the proxy will kill the session.