Merge branch '2.2' into 2.2-mrm

Documentation/About/Limitations.md

@@ -78,16 +78,13 @@ transaction or change the autocommit mode using a prepared statement.
 
 * Compression is not included in the MySQL server handshake.
 
-* MariaDB MaxScale will intercept `KILL <thread_id>` statements which are of the
-form `KILL 3`, `KILL CONNECTION 321` and `KILL QUERY 8`. These queries are not
-routed to backends because the `<thread_id>` sent by the client does not equal a
-backend id. MaxScale reacts to a thread kill command by killing the session with
-the given id if the user and host of the issuing session and the target session
-match. Query kill command is not supported and results in an error message. For
-MaxScale to recognize the *KILL* statement, the statement must start right after
-the command byte, have no comments and have minimal whitespace. These
-limitations are in place to limit the parsing MaxScale needs to do to every
-query.
+* MariaDB MaxScale does not support `KILL QUERY ID <query_id>` type
+  statements. If a query by a query ID is to be killed, it needs to be done
+  directly on the backend databases.
+
+* The `KILL` commands are executed asynchronously and the results are
+  ignored. Due to this, they will always appear to succeed even if the user is
+  lacking the permissions.
 
 ## Authenticator limitations
 

Documentation/Getting-Started/Configuration-Guide.md

@@ -196,6 +196,24 @@ write or modify the data in the backend server. The default is 2 seconds.
 auth_write_timeout=10
 ```
 
+#### `query_retries`
+
+The number of times an interrupted query will be retried. This feature was added
+in MaxScale 2.1.10 and is disabled by default.
+
+An interrupted query is any query that is interrupted by a network
+error. Connection timeouts are included in network errors and thus is it
+advisable to make sure that the value of `query_retry_timeout` is set to an
+adequate value.
+
+#### `query_retry_timeout`
+
+The total timeout in seconds for any retried queries. The default value is 5
+seconds.
+
+An interrupted query is retried for either the configured amount of attempts or
+until the configured timeout is reached.
+
 #### `passive`
 
 Controls whether MaxScale is a passive node in a cluster of multiple MaxScale

Documentation/Release-Notes/MaxScale-2.1.10-Release-Notes.md

@@ -22,6 +22,20 @@ release notes:
 For any problems you encounter, please consider submitting a bug report at
 [Jira](https://jira.mariadb.org).
 
+## Changed Features
+
+### Internal Query Retries
+
+The internal SQL queries that MaxScale executes to load database users as well
+as monitor the database itself can now be automatically retried if they are
+interrupted. The new global parameter, `query_retries` controls the number of
+retry attempts each query will receive if it fails due to a network problem.
+The `query_retry_timeout` global parameter controls the total timeout for the
+retries.
+
+To enable this functionality, add `query_retries=<number-of-retries>` under the
+`[maxscale]` section where _<number-of-retries>_ is a positive integer.
+
 ## Bug fixes
 
 [Here is a list of bugs fixed in MaxScale 2.1.10.](https://jira.mariadb.org/issues/?jql=project%20%3D%20MXS%20AND%20issuetype%20%3D%20Bug%20AND%20status%20%3D%20Closed%20AND%20fixVersion%20%3D%202.1.10)

Documentation/Release-Notes/MaxScale-2.2.0-Release-Notes.md

@@ -197,10 +197,14 @@ to the server. For more information, see the server section in the
 
 ### KILL command support
 
-The MySQL client protocol now detects `KILL <thread_id>` statements (binary and
-query forms) and kills the MaxScale session with the given id. This feature has
-some limitations, see [Limitations](../About/Limitations.md) for more
-information.
+The MySQL client protocol now supports execution of `KILL` statements through
+MaxScale. The connection IDs in these queries will be transformed into the
+correct ones by MaxScale.
+
+`KILL QUERY ID <query_id>` is not supported by MaxScale and it needs to be
+executed directly on the relevant backend server. In addition to this, there are
+minor limitations to the `KILL` command handling. See
+[Limitations](../About/Limitations.md) for more information.
 
 ### New `uses_function` rule for dbfwfilter