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Key Technical Parameters (GUC)

Domino v2 provides a rich set of GUC parameters to finely control component behavior.

Kernel GUC

Parameter	Description
`mx_stream_default_version`	Default version. Set to 2 to create v2 streams by default.
`mx_stream_internal_modify`	Used internally by stream processing. Controls whether data can be written to stream tables.
`mx_stream_debug_snapshot`	Enables printing of debug information for historical snapshots.
`mx_stream_wal_keep_size`	Maximum retention size for Domino v1/v2 XLog. Exceeding this value disables the stream (v1) or decoder (v2).
`mx_stream_enable_segment_set_launch`	Whether to start stream processing only on nodes within the segment_set.
`mx_enable_stream`	Global toggle for Domino v1.
`mx_stream_set_do_not_stream`	Prevents changes generated by REFRESH STREAM from participating in downstream stream computations.
`mx_max_number_streams`	Maximum number of streams allowed in Domino v1.
`mx_stream_worker_launch_timeout`	Wait time before restarting a failed Domino v1 stream processing process. Default is 1 minute.
`mx_stream_gc_period`	Interval for checking and handling leaked stream progress or slots in Domino v1. Default is 5 minutes; set to 0 to disable.
`mx_stream_base_backup_timeout`	Timeout for basebackup to wait for stream processing to catch up to startptr. Basebackup is aborted if this duration is exceeded.
`mx_stream_message_level`	Log level for Domino v1.
`logical_decoding_work_mem`	Controls memory used by logical decoding to cache uncommitted transactions. When exceeded, the largest transaction is spilled until total memory falls below this value. Unit is KB. Default is 65536 (64 MB).

Domino v1 GUC

Parameter	Description
`mxstream.debug_tuple_decoding`	Enables debug logging for v1 decoding.
`mxstream.enable_sharescan`	Enables sharescan for v1.
`mxstream.debug_plan`	Enables printing of plan explain information when creating a stream in v1.
`mxstream.debug_plan_costs` / `mxstream.debug_plan_verbose`	Controls what information is included in the plan explain output when creating a stream in v1.
`mxstream.skip_decode`	Prevents current session writes from participating in stream computation. Applies to both v1 and v2.
`mxstream.scan_xlog_size_limit`	Controls how much XLog is decoded per stream computation cycle in v1.
`mxstream.scan_tuples_limit`	Controls how many tuples are scanned per stream computation cycle in v1.
`mxstream.skip_valid_xlog`	Skips CRC checks on irrelevant records during v1 stream decoding.

Domino v2 GUC

Parameter	Description
`domino.debug` / `domino.debug2`	Enables/disables debug logging.
`domino.decode_interval`	Controls decoder interval. Only effective when decode delay is below this value; otherwise, decoding proceeds as fast as possible.
`domino.enabled`	Global toggle for Domino v2. Controls whether the Domino ticker and scheduler processes are started. Default is off in version 6.3.X. Requires restart to take effect.
`domino.max_number_decoders`	Maximum number of decoders for v2. Each database uses one decoder; this limits the number of supported databases.
`domino.max_workers`	Controls the number of Domino v2 workers. Workers are shared across databases that have stream tables.
`domino.max_streams`	Maximum number of streams for Domino v2. Default is 1024. This setting controls shared memory allocation and is not a recommendation to create 1024 streams.
`domino.job_retry_timeout_ms`	Retry interval after a stream fails. Default is 60 seconds.
`domino.scan_limit`	Number of ticks to scan at once. Valid values: -1 (no limit), 1 (one tick).
`domino.scan_interval`	Minimum interval between two stream scans. Only takes effect when stream latency is less than decode_interval + scan_interval.
`domino.ticker_interval_mb` / `domino.ticker_interval_ms`	Interval for ticker to create ticks, based on time elapsed or XLog growth.
`domino.tlog_keep_size (MB)`	Number of TLogs retained for stream processing. If stream progress lags behind decoding and retained TLogs exceed this value, TLog retention stops and the stream fails with "could not open tlog file ...".
`domino.worker_timeout_ms`	Automatic restart interval for stream processing processes.
`domino.streaming_leaf`	*Experimental feature* Controls whether output from the last-layer stream is decoded. Default is off. Can be enabled to address performance bottlenecks. Not recommended during stream creation, as enabling it while creating an upstream stream may cause missing data when downstream streams are added.

Function practice