Firebird-5-Release-Notes | Configuration Additions And Changes

New configuration parameters:

Parameters for Parallel Operations

MaxParallelWorkers

Limits the total number of parallel workers that can be created within a single Firebird process for each attached database.Integer values in the range between 1 (no parallelism) and 64 are allowed.All other values are silently ignored and the default value of 1 is used.

Note	Workers are accounted for each attached database independently.

ParallelWorkers

Specifies the default number of parallel workers for a single task.Integer values in the range between 1 (no parallelism) and MaxParallelWorkers (see above) are allowed.All other values are silently ignored and the default value of 1 is used.

Other Parameters

MaxStatementCacheSize

Defines the maximum amount of memory used to cache unused DSQL compiled statements.A value of zero (‘0’) means no statement caching is used.Default value is 2 megabytes.

OnDisconnectTriggerTimeout

Configures a timeout (in seconds) that is applied to the ON DISCONNECT trigger execution.The trigger will be automatically cancelled by the engine after the specified time has passed.A value of zero (‘0’) means no timeout is set.Default value is 180 seconds.

DefaultProfilerPlugin

Specifies the default profiler plugin used to profile connections using the RDB$PROFILER package.

OptimizeForFirstRows

Defines whether queries should be optimized to retrieve the first records as soon as possible rather than returning the whole dataset as soon as possible.By default, retrieval of all rows is implied by the optimizer.

OuterJoinConversion

Defines whether OUTER joins can be converted into INNER joins by the optimizer, provided that such a transformation is possible from the query result perspective.

Enabled by default.Can be disabled to simplify the migration path if OUTER joins are used intentionally in SQL queries (e.g. as optimizer hints) even if they are known to be semantically equivalent to INNER joins.

SubQueryConversion

Defines whether IN/ANY/EXISTS sub-queries can be unnested and merged with the outer query using the semi-join algorithm, provided that such a transformation is possible.

Caution

Being en experimental feature, it’s disabled by default.

It can be enabled to benefit from a possibly better performance due to sub-query being evaluated just once and then cached.However, it may also lead to a worse performance in some cases, e.g. when the sub-query returns many rows.Please test with real-world use cases before enabling this conversion in a production environment.

Changed configuration parameters

WireCryptPlugin

A new variant of the ChaCha#20 plugin was added.It uses a 64-bit internal counter rather than 32-bit.The new default value of this parameter is now ChaCha64, ChaCha, Arc4.

Replication Configuration Additions and Changes

cascade_replication

Specifies whether changes applied to the replica database will be also subject of further replication (if any configured).Default value is false (cascading is disabled).

Allow macros in replication.conf

Configuration file macros are now also supported in replication.conf.

Removed configuration parameters

RemotePipeName

This parameter was removed along with the removal of WNET (aka named pipes) protocol support for Windows.

TcpLoopbackFastPath

This parameter was removed because Microsoft discourages using the SIO_LOOPBACK_FAST_PATH socket option.

Configuration Additions And Changes

Configuration Additions and Changes