Release Notes for MariaDB MaxScale 2.5.21

Can Result in Crashes, Hangs, Stalls

• When Binlog Router (binlogrouter) is used, a race condition can cause MaxScale to crash. (MXS-4138)

• When the connection_keepalive parameter is 0, a memory leak can cause MaxScale to crash. (MXS-4100, MXS-4141)

• When Avrorouter replicates binary log events that reference sequencessequences, MaxScale can crash. (MXS-4120)

Can Result in Unexpected Behavior

• When the same query is executed multiple times, the size of the query classifier cache could incorrectly increase, even though the query was only cached once. (MXS-4194)

  • In earlier releases, repeatedly executing a query could cause the size of the query classifier cache to surpass the value of the query_classifier_cache_size parameter, which would cause the query classifier cache to be disabled.

  • Starting with this release, the size of the query classifier cache is updated correctly when the same query is executed multiple times.

• When TLS is enabled, MaxScale tries to generate 512-bit RSA keys, which are disabled when OpenSSL is running in FIPS mode. (MXS-4181)

  • In earlier releases, when this issue occurred on a system using OpenSSL 1.0.1 (such as some older CentOS 7 and RHEL 7 releases), the following error messages would be written to the MaxScale log:

    error  : (SERVER_NAME); 512-bit RSA key generation failed.
    error  : (SERVER_NAME); Unable to initialize SSL for server 'SERVER_NAME'
    error  : Failed to create a new server.
    

• When maxctrl show filters is executed, the output does not contain filter diagnostics. (MXS-4166)

• When the Cat Router (cat) is used, sessions are not always closed, which can trigger a debug assertion to fail. (MXS-4164)

• The max_slave_replication_lag parameter could not be set to a non-zero value with Galera Monitor (galeramon). (MXS-4160)

  • In earlier releases, when the max_slave_replication_lag parameter was set to a non-zero value with Galera Monitor (galeramon), the following error message would be written to the MaxScale log when Read/Write Split Router (readwritesplit) tried to route a query to a replica node:

    Could not find valid server for target type TARGET_SLAVE (COM_QUERY: QUERY_TEXT), closing connection.
    

• When Schema Router (schemarouter) is used and duplicate table checks are not disabled with the ignore_tables_regex parameter, the cost of performing the duplicate table check grows very quickly as the number of tables increases. (MXS-4151)

• When Schema Router (schemarouter) is used, query routing performance scales poorly as the number of tables increases. (MXS-4152)

• When the connection_keepalive parameter is non-zero, MaxScale sends pings to servers even if the client is idle. (MXS-4139)

• When MariaDB Monitor (mariadbmon) performs failover, MaxScale writes a CHANGE MASTER TO statementCHANGE MASTER TO statement containing the replication user's user name and password in plain text to the MaxScale Log. (MXS-4115)

  • Starting with this release, the user name and password are masked in the statement written to the MaxScale Log.

• When multiple servers are selected as Master with Read Connection Router (readconnroute), the rank parameter is ignored for all servers except the last one. (MXS-4132)

  • In earlier releases, this could impact query routing in some configurations. For example, let's say that two servers are selected as Master: the first has rank=primary, and the second has rank=secondary. When router_options=master is set, Read Connection Router (readconnroute) chooses the second server, because the rank of the first server is ignored.

• When a service uses the targets parameter to route queries to a second service, the second service is not shown as a target in the output of maxctrl list services. (MXS-4127)

• If the value of the query_classifier_cache_size parameter is set high, executing maxctrl show qc_cache can cause MaxCtrl to run out of memory. (MXS-4121)

• When Schema Router (schemarouter) is used, the sys schema is not automatically ignored for duplicate checks. (MXS-4110)

  • In earlier releases, the ignore_tables_regex parameter would have to be used to configure Schema Router (schemarouter) to ignore the sys schema when used with MariaDB Enterprise Server 10.6.

  • Starting with this release, Schema Router (schemarouter) will automatically ignore the sys schema for duplicate checks.

Install and Upgrade

• When the MaxScale package is installed, the /etc/maxscale.cnf.d/ directory is not automatically created. (MXS-4134)