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Key Technical Parameters (GUC)

Domino v2 provides rich GUC parameters for fine-grained control of component behavior.

Kernel GUC

Parameters	Description
`mx_stream_default_version`	Default version, if set to 2, the default v2 stream is created.
`mx_stream_internal_modify`	Stream calculation is used internally. Controls whether writing data to the flow table is allowed.
`mx_stream_debug_snapshot`	Whether to print historical snapshot debug information.
`mx_stream_wal_keep_size`	Domino v1/v2 XLog log retains maximum value, if the value exceeds the stream (v1) or the decoder (v2) fails.
`mx_stream_enable_segment_set_launch`	Whether to start stream calculations only on the segment_set node.
`mx_enable_stream`	Domino v1 global switch.
`mx_stream_set_do_not_stream`	Used to control the changes generated by REFRESH STREAM do not participate in downstream flow calculations.
`mx_max_number_streams`	The maximum number of streams allowed by Domino v1.
`mx_stream_worker_launch_timeout`	How long does it take to start again after the Domino v1 stream calculation process error? The default is 1 minute.
`mx_stream_gc_period`	Domino v1 Checks and handles leak flow progress or slot period, defaults to 5 minutes, set to 0 to turn off.
`mx_stream_base_backup_timeout`	basebackup Wait for the flow calculation progress to catch up with startptr, and abandon basebackup after that time.
`mx_stream_message_level`	Domino v1 log level.
`logical_decoding_work_mem`	Controls how much memory is used to cache uncommitted transactions. After exceeding this value, select the transaction Spill that takes up the most memory until the total memory is lower than the GUC configuration. The unit is KB, and the default value is 65536, that is, 64MB.

Domino v1 GUC

Parameters	Description
`mxstream.debug_tuple_decoding`	Controls whether v1 prints decoded debug information.
`mxstream.enable_sharescan`	Controls whether sharescan is enabled by v1.
`mxstream.debug_plan`	Control v1 prints the explanation information of plan when creating a stream.
`mxstream.debug_plan_costs` / `mxstream.debug_plan_verbose`	Controls what information is included in the explanation information of v1 when printing the plan when creating a stream.
`mxstream.skip_decode`	Controls that the content written by the current session does not participate in stream calculations, both v1 and v2 are applicable.
`mxstream.scan_xlog_size_limit`	Controls how much decoded by v1 streaming calculation of XLog.
`mxstream.scan_tuples_limit`	Controls how many scans are performed by v1 at a time stream.
`mxstream.skip_valid_xlog`	Controls the CRC check for unrelated records skips when the v1 stream is calculated and decoded.

Domino v2 GUC

Parameters	Description
`domino.debug` / `domino.debug2`	Turn on/off the debug log.
`domino.decode_interval`	Controls the decoder decoding interval, valid only if the decoding delay is lower than this value, and decodes as soon as possible if the value has been exceeded.
`domino.enabled`	domino v2 global switch, controlling whether to start the domino ticker and scheduler processes. In version 6.3.X, it defaults to off and needs to be restarted to take effect.
`domino.max_number_decoders`	v2 The maximum number of decoders, each database uses one decoder, and supports up to so many databases.
`domino.max_workers`	Controls the number of domino v2 workers. If multiple databases have flow tables, the worker is shared by multiple databases.
`domino.max_streams`	Controls the upper limit of domino v2 streams, default 1024. Note that this is used to control shared memory and other sizes, and it is not recommended to create 1024 streams.
`domino.job_retry_timeout_ms`	Control how long to wait for retry after an error in flow operation. The default is 60s.
`domino.scan_limit`	How many ticks are scanned at a time. Valid values: -1 means no limit; 1 means 1 tick.
`domino.scan_interval`	The minimum interval between two scans is calculated, and it takes effect only if the stream delay is less than decode_interval + scan_interval.
`domino.ticker_interval_mb` / `domino.ticker_interval_ms`	ticker The interval for creating ticks, how long to wait or how much xlog increases.
`domino.tlog_keep_size (MB)`	Calculate how much TLog is reserved for the stream. If the stream calculation progress cannot keep up with the decoding progress, the TLog retention exceeds this value, the stream no longer retains TLog, and the stream will report an error "can not open tlog file..."
`domino.worker_timeout_ms`	How long does the stream calculation process work automatically restart.
`domino.streaming_leaf`	*Test Features* Controls whether the output of the last layer stream is decoded, it is turned off by default, and you can try to turn it on when the performance encounters a bottleneck. It is not recommended to open when creating a stream, because if it is opened when creating an upstream stream, it will be considered the last layer, and data will be missing when creating a downstream stream.