This change history is a high level summary of selected changes that may impact applications and/or break backwards compatibility. See also the CHANGES file in the source distribution for a complete list of changes.

1.6.0-alpha Release date: TBD Motto/theme: Maintenance and initial MySQL Fabric support This is the current development series. All features are at an early stage. Changes may happen at any time without prior notice. Please, do not use this version in production environments. The documentation may not reflect all changes yet. Bug fixes Won't fix: #66616 R/W split fails: QOS with mysqlnd_get_last_gtid with built-in MySQL GTID This is not a bug in the plugins implementation but a server side feature limitation not considered and documented before. MySQL 5.6 built-in GTIDs cannot be used to ensure session consistency when reading from slaves in all cases. In the worst case the plugin will not consider using the slaves and fallback to using the master. There will be no wrong results but no benefit from doing GTID checks either. Fixed #66064 - Random once load balancer ignoring weights Due to a config parsing bug random load balancing has ignored node weights if, and only if, the sticky flag was set (random once). Fixed #65496 - Wrong check for slave delay The quality of service filter has erroneously ignored slaves that lag for zero (0) seconds if a any maximum lag had been set. Although a slave was not lagging behind, it was excluded from the load balancing list if a maximum age was set by the QoS filter. This was due to using the wrong comparison operator in the source of the filter. Fixed #65408 - Compile failure with -Werror=format-security Feature changes Introduced an internal connection pool. When using Fabric and switching from shard group A to shard group B, we are replacing the entire list of masters and slaves. This troubles the connections state alignment logic and some filters. Some filters cache information on the master and slave lists. The new internal connection pool abstraction allows us to inform the filters of changes, hence they can update their caches. Later on, the pool can also be used to reduce connection overhead. Assume you are switching from a shard group to another and back again. Whenever the switch is done, the pool's active server (and connection) lists are replaced. However, no longer used connections are not necessarily closed immediately but can be kept in the pool for later reuse. Please note, the connection pool is internalat this point. There are some new statistics to monitor it. However, you cannot yet configure pool size of behaviour. Added a basic distributed transaction abstraction. XA transactions can are supported ever since using standard SQL calls. This is inconvenient as XA participants must be managed manually. PECL/mysqlnd_ms introduces API calls to control XA transaction among MySQL servers. When using the new functions, PECL/mysqlnd_ms acts as a transaction coordinator. After starting a distributed transaction, the plugin tracks all servers involved until the transaction is ended and issues appropriate SQL statements on the XA participants. This is useful, for example, when using Fabric and sharding. When using Fabric the actual shard servers involved in a business transaction may not be known in advance. Thus, manually controlling a transaction that spawns multiple shards becomes difficult. Please, be warned about current limitations. Introduced automatic retry loop for transient errors and corresponding statistic to count the number of implicit retries. Some distributed database clusters use transient errors to hint a client to retry its operation in a bit. Most often, the client is then supposed to halt execution (sleep) for a short moment before retrying the desired operation. Immediately failing over to another node is not necessary in response to the error. Instead, a retry loop can be performed. Common situation when using MySQL Cluster. Introduced automatic retry loop for transient errors and corresponding statistic to count the number of implicit retries. Some distributed database clusters use transient errors to hint a client to retry its operation in a bit. Most often, the client is then supposed to halt execution (sleep) for a short moment before retrying the desired operation. Immediately failing over to another node is not necessary in response to the error. Instead, a retry loop can be performed. Common situation when using MySQL Cluster. Introduced most basic support for the MySQL Fabric High Availability and sharding framework. Please, consider this pre-alpha quality. Both the server side framework and the client side code is supposed to work flawless considering the MySQL Fabric quickstart examples only. However, testing has not been performed to the level of prior plugin alpha releases. Either sides are moving targets, API changes may happen at any time without prior warning. As this is work in progress, the manual may not yet reflect allow feature limitations and known bugs. New statistics to monitor the Fabric XML RPC call sharding.lookup_servers: fabric_sharding_lookup_servers_success, fabric_sharding_lookup_servers_failure, fabric_sharding_lookup_servers_time_total, fabric_sharding_lookup_servers_bytes_total, fabric_sharding_lookup_servers_xml_failure. New functions related to MySQL Fabric: mysqlnd_ms_fabric_select_shard, mysqlnd_ms_fabric_select_global, mysqlnd_ms_dump_servers.

1.5.1-stable Release date: 06/2013 Motto/theme: Sharding support, improved transaction support This is the current stable series. Use this version in production environments. The documentation is complete. 1.5.0-alpha Release date: 03/2013 Motto/theme: Sharding support, improved transaction support Bug fixes Fixed #60605 PHP segmentation fault when mysqlnd_ms is enabled. Setting transaction stickiness disables all load balancing, including automatic failover, for the duration of a transaction. So far connection switches could have happened in the middle of a transaction in multi-master configurations and during automatic failover although transaction monitoring had detected transaction boundaries properly. BC break and bug fix. SQL hints enforcing the use of a specific kind of server (MYSQLND_MS_MASTER_SWITCH, MYSQLND_MS_SLAVE_SWITCH, MYSQLND_MS_LAST_USED_SWITCH) are ignored for the duration of a transaction of transaction stickiness is enabled and transaction boundaries have been detected properly. This is a change in behaviour. However, it is also a bug fix and a step to align behaviour. If, in previous versions, transaction stickiness, one of the above listed SQL hints and the quality of service filtering was combined it could happened that the SQL hints got ignored. In some case the SQL hints did work, in other cases they did not. The new behaviour is more consistent. SQL hints will always be ignore for the duration of a transaction, if transaction stickiness is enabled. Please note, transaction boundary detection continues to be based on API call monitoring. SQL commands controlling transactions are not monitored. BC break and bug fix. Calls to mysqlnd_ms_set_qos will fail when done in the middle of a transaction if transaction stickiness is enabled. Connection switches are not allowed for the duration of a transaction. Changing the quality of service likely results on a different set of servers qualifying for query execution, possibly making it necessary to switch connections. Thus, the call is not allowed in during an active transaction. The quality of server can, however, be changed in between transactions. Feature changes Introduced the node_group filter. The filter lets you organize servers (master and slaves) into groups. Queries can be directed to a certain group of servers by prefixing the query statement with a SQL hint/comment that contains the groups configured name. Grouping can be used for partitioning and sharding, and also to optimize for local caching. In the case of sharding, a group name can be thought of like a shard key. All queries for a given shard key will be executed on the configured shard. Note: both the client and server must support sharding for sharding to function with mysqlnd_ms. Extended configuration file validation during PHP startup (RINIT). An E_WARNING level error will be thrown if the configuration file can not be read (permissions), is empty, or the file (JSON) could not be parsed. Warnings may appear in log files, which depending on how PHP is configured. Distributions that aim to provide a pre-configured setup, including a configuration file stub, are asked to put {} into the configuration file to prevent this warning about an invalid configuration file. Further configuration file validation is done when parsing sections upon opening a connection. Please, note that there may still be situations when an invalid plugin configuration file does not lead to proper error messages but a failure to connect. As of PHP 5.5.0, improved support for transaction boundaries detection was added for mysqli. The mysqli extension has been modified to use the new C API calls of the mysqlnd library to begin, commit, and rollback a transaction or savepoint. If trx_stickiness is used to enable transaction aware load balancing, the mysqli_begin, mysqli_commit and mysqli_rollback functions will now be monitered by the plugin, to go along with the mysqli_autocommit function that was already supported. All SQL features to control transactions are also available through the improved mysqli transaction control related functions. This means that it is not required to issue SQL statements instead of using API calls. Applications using the appropriate API calls can be load balanced by PECL/mysqlnd_ms in a completely transaction-aware way. Please note, PDO_MySQL has not been updated yet to utilize the new mysqlnd API calls. Thus, transaction boundary detection with PDO_MySQL continues to be limited to the monitoring by passing in PDO::ATTR_AUTOCOMMIT to PDO::setAttribute. Introduced trx_stickiness=on. This trx_stickiness option differs from trx_stickiness=master as it tries to execute a read-only transaction on a slave, if quality of service (consistency level) allows the use of a slave. Read-only transactions were introduced in MySQL 5.6, and they offer performance gains. Query cache support is considered beta if used with the mysqli API. It should work fine with primary copy based clusters. For all other APIs, this feature continues to be called experimental. The code examples in the mysqlnd_ms source were updated.

1.4.2-stable Release date: 08/2012 Motto/theme: Tweaking based on user feedback 1.4.1-beta Release date: 08/2012 Motto/theme: Tweaking based on user feedback Bug fixes Fixed build with PHP 5.5 1.4.0-alpha Release date: 07/2012 Motto/theme: Tweaking based on user feedback Feature changes BC break: Renamed plugin configuration setting ini_file to config_file. In early versions the plugin configuration file used ini style. Back then the configuration setting was named accordingly. It has now been renamed to reflect the newer file format and to distinguish it from PHP's own ini file (configuration directives file). Introduced new default charset setting server_charset to allow proper escaping before a connection is opened. This is most useful when using lazy connections, which are a default. Introduced wait_for_gtid_timeout setting to throttle slave reads that need session consistency. If global transaction identifier are used and the service level is set to session consistency, the plugin tries to find up-to-date slaves. The slave status check is done by a SQL statement. If nothing else is set, the slave status is checked only one can the search for more up-to-date slaves continues immediately thereafter. Setting wait_for_gtid_timeout instructs the plugin to poll a slaves status for wait_for_gtid_timeout seconds if the first execution of the SQL statement has shown that the slave is not up-to-date yet. The poll will be done once per second. This way, the plugin will wait for slaves to catch up and throttle the client. New failover strategy loop_before_master. By default the plugin does no failover. It is possible to enable automatic failover if a connection attempt fails. Upto version 1.3 only master strategy existed to failover to a master if a slave connection fails. loop_before_master is similar but tries all other slaves before attempting to connect to the master if a slave connection fails. The number of attempts can be limited using the max_retries option. Failed hosts can be remembered and skipped in load balancing for the rest of the web request. max_retries and remember_failed are considered experimental although decent stability is given. Syntax and semantics may change in the future without prior notice.

1.3.2-stable Release date: 04/2012 Motto/theme: see 1.3.0-alpha Bug fixes Fixed problem with multi-master where although in a transaction the queries to the master weren't sticky and were spread all over the masters (RR). Still not sticky for Random. Random_once is not affected. 1.3.1-beta Release date: 04/2012 Motto/theme: see 1.3.0-alpha Bug fixes Fixed problem with building together with QC. 1.3.0-alpha Release date: 04/2012 Motto/theme: Query caching through quality-of-service concept The 1.3 series aims to improve the performance of applications and the overall load of an asynchronous MySQL cluster, for example, a MySQL cluster using MySQL Replication. This is done by transparently replacing a slave access with a local cache access, if the application allows it by setting an appropriate quality of service flag. When using MySQL replication a slave can serve stale data. An application using MySQL replication must continue to work correctly with stale data. Given that the application is know to work correctly with stale data, the slave access can transparently be replace with a local cache access. PECL/mysqlnd_qc serves as a cache backend. PECL/mysqlnd_qc supports use of various storage locations, among others main memory, APC and MEMCACHE. Feature changes Added cache option to quality-of-service (QoS) filter. New configure option enable-mysqlnd-ms-cache-support New constant MYSQLND_MS_HAVE_CACHE_SUPPORT. New constant MYSQLND_MS_QOS_OPTION_CACHE to be used with mysqlnd_ms_set_qos. Support for built-in global transaction identifier feature of MySQL 5.6.5-m8 or newer.

1.2.1-beta Release date: 01/2012 Motto/theme: see 1.2.0-alpha Minor test changes. 1.2.0-alpha Release date: 11/2011 Motto/theme: Global Transaction ID injection and quality-of-service concept In version 1.2 the focus continues to be on supporting MySQL database clusters with asynchronous replication. The plugin tries to make using the cluster introducing a quality-of-service filter which applications can use to define what service quality they need from the cluster. Service levels provided are eventual consistency with optional maximum age/slave slag, session consistency and strong consistency. Additionally the plugin can do client-side global transaction id injection to make manual master failover easier. Feature changes Introduced quality-of-service (QoS) filter. Service levels provided by QoS filter: eventual consistency, optional option slave lag session consistency, optional option GTID strong consistency Added the mysqlnd_ms_set_qos function to set the required connection quality at runtime. The new constants related to mysqlnd_ms_set_qos are: MYSQLND_MS_QOS_CONSISTENCY_STRONG MYSQLND_MS_QOS_CONSISTENCY_SESSION MYSQLND_MS_QOS_CONSISTENCY_EVENTUAL MYSQLND_MS_QOS_OPTION_GTID MYSQLND_MS_QOS_OPTION_AGE Added client-side global transaction id injection (GTID). New statistics related to GTID: gtid_autocommit_injections_success gtid_autocommit_injections_failure gtid_commit_injections_success gtid_commit_injections_failure gtid_implicit_commit_injections_success gtid_implicit_commit_injections_failure Added mysqlnd_ms_get_last_gtid to fetch the last global transaction id. Enabled support for multi master without slaves.

1.1.0 Release date: 09/2011 Motto/theme: Cover replication basics with production quality The 1.1 and 1.0 series expose a similar feature set. Internally, the 1.1 series has been refactored to plan for future feature additions. A new configuration file format has been introduced, and limitations have been lifted. And the code quality and quality assurance has been improved. Feature changes Added the (chainable) filter concept: BC break: mysqlnd_ms_set_user_pick_server has been removed. Thehttp://svn.php.net/viewvc/pecl/mysqlnd_ms/trunk/ user filter has been introduced to replace it. The filter offers similar functionality, but see below for an explanation of the differences. New powerful JSON based configuration syntax. Lazy connections improved: security relevant, and state changing commands are covered. Support for (native) prepared statements. New statistics: use_master_guess, use_slave_guess. BC break: Semantics of statistics changed for use_slave, use_master. Future changes are likely. Please see, mysqlnd_ms_get_stats. List of broadcasted messages extended by ssl_set. Library calls now monitored to remember settings for lazy connections: change_user, select_db, set_charset, set_autocommit. Introduced mysqlnd_ms.disable_rw_split. The configuration setting allows using the load balancing and lazy connection functionality independently of read write splitting. Bug fixes Fixed PECL #22724 - Server switching (mysqlnd_ms_query_is_select() case sensitive) Fixed PECL #22784 - Using mysql_connect and mysql_select_db did not work Fixed PECL #59982 - Unusable extension with --enable-mysqlnd-ms-table-filter. Use of the option is NOT supported. You must not used it. Added note to m4. Fixed Bug #60119 - host="localhost" lost in mysqlnd_ms_get_last_used_connection() The mysqlnd_ms_set_user_pick_server function was removed, and replaced in favor of a new user filter. You can no longer set a callback function using mysqlnd_ms_set_user_pick_server at runtime, but instead have to configure it in the plugins configuration file. The user filter will pass the same arguments to the callback as before. Therefore, you can continue to use the same procedural function as a callback.callback It is no longer possible to use static class methods, or class methods of an object instance, as a callback. Doing so will cause the function executing a statement handled by the plugin to emit an E_RECOVERABLE_ERROR level error, which might look like: "(mysqlnd_ms) Specified callback (picker) is not a valid callback." Note: this may halt your application.

1.0.1-alpha Release date: 04/2011 Motto/theme: bug fix release 1.0.0-alpha Release date: 04/2011 Motto/theme: Cover replication basics to test user feedback The first release of practical use. It features basic automatic read-write splitting, SQL hints to overrule automatic redirection, load balancing of slave requests, lazy connections, and optional, automatic use of the master after the first write. The public feature set is close to that of the 1.1 release. 1.0.0-pre-alpha Release date: 09/2010 Motto/theme: Proof of concept Initial check-in. Essentially a demo of the mysqlnd plugin API.