Skip to content


Instance tables

A framework is provided to perform housekeeping on in-memory tables to prevent them from growing unbounded and bloating the process memory.

Tables can be specified for clean-up by adding parameters to the enhanced instance parameter override. The supported values are in the table below.

parameter type default description
.px.cln.startTime time 00:00:00.0 Time to run instance table clean-up (UTC)
.px.cln.frequency int 24 Interval between clean-up runs (hours)
.px.cln.table string Specifies the tables, number of hours to keep and min number of rows before cleanup (format is table,hours,rows)

The .px.cln.table format specifies the table name, number of hours to keep and the row threshold for housekeeping (optional). If the number of rows is below the threshold, houskeeping will not run.


The target table must have a time column of type timestamp or datettime

  • Cleanup the .pm.accesslog table if it exceeds 10,000 rows and keep the last 24 hours - .pm.accesslog,24,10000
  • Cleanup the .pm.querylog table and only keep the last 24 hours (no row limit) - .pm.accesslog,24,

The .px.cln.table field can be repeating to perform housekeeping for multiple tables.


Instance parameters

Control housekeeping

There are several housekeeping tasks that run on Control, performing various actions:

  • dc_housekeeping_auto_export.1 - exports any packages listed as autoExportPackage in DC_EXPORT:DEFAULT config parameter
  • dc_housekeeping_dc_checkpoint.1 - runs a Control checkpoint
  • dc_housekeeping_garbage_collection.1 - runs garbage collection on Control process to free-up memory
  • dc_housekeeping_qsrc_archive.1 - makes a backup of the qsrc folder to the qsrcarchive directory
  • dc_housekeeping_tdir_archive.1 - makes a backup of the tdir folder to the tdirarchive directory
  • dc_housekeeping_tdir_checkpoint.1 - runs a tdir checkpoint and clears the transaction log
  • dc_housekeeping_tdir_historise.1 - archives old data for audit tables to disk. Controlled by the housekeeping:<DEFAULT> configuration

These tasks run on default schedules. This can be changed by editing the tasks in KX Control. The tasks can also be run manually from KX Control. The default schedules are shown below

housekeeping tasks default schedule
dc_housekeeping_auto_export.1 not scheduled
dc_housekeeping_dc_checkpoint.1 every Monday at 0000
dc_housekeeping_garbage_collection.1 not scheduled
dc_housekeeping_qsrc_archive.1 every 12 hours
dc_housekeeping_tdir_archive.1 every 12 hours
dc_housekeeping_tdir_checkpoint.1 every hour
dc_housekeeping_tdir_historise.1 every day at 0000

The ${DELTADATA_HOME}/DeltaControlData directory contains persisted Control data, files and backups:


  • tdir - persistence of in-memory Control data
  • tdirarchive - contains archives of previous versions of tdir
  • qsrc - contains process template files
  • qsrcarchive - contains archives of previous versions of qsrc
  • localRepo - contains Control workspace data used for KX Control
  • tdirhist - location of historised data

See Persistence for more information.

tdir_historise task

The dc_housekeeping_tdir_historise.1 task will run every day by default. It archives data from Control tables to disk in the directory ${DELTADATA_HOME}/DeltaControlData/tdirhist. The tables to archive and how many days data to keep in Control memory is configured using the housekeeping:<DEFAULT> parameter.


For example, any data older than 5 days will be removed from the .pm.querylog table in Control and archived to ${DELTADATA_HOME}/DeltaControlData/tdirhist when the dc_housekeeping_tdir_historise.1 task runs.

AXSTATE and revision housekeeping

dc_housekeeping_tdir_historise.1 can also be used to clean out entity revisions older than a certain number of days from ${DELTADATA_HOME}/DeltaControlData/localRepo/AXSTATE. To enable this, add AXSTATE to the housekeeping:<DEFAULT> param.

When dc_housekeeping_tdir_historise.1 runs on schedule, entity revisions older than the configured number of days will be dropped, excluding the active revision, which will be kept regardless of age.

AXSTATE compression

Setting the environment variable AXSTATE_COMPRESSION to 'yes' will compress new AXSTATE tables.

By default, compression will use the settings 17 2 6, which are the blockSize, algorithm (gzip), and zip levels respectively.

Optionally setting AXSTATE_COMPRESSION_SETTINGS to a list of 3 integers will set the compression options as supported by set


To compress an existing table, use the internal function -19! to backup and write down each column as compressed.

See Also: Archiving files

Back to top