---
sourceDocument: Yokohama IT Operations Management
sourceDocumentLink: https://servicenow-prod.fluidtopics.net/r/yokohama/it-operations-management

 Release :

    - yokohama

ft:locale :

    - en-US

ft:publication_title :

    - Yokohama IT Operations Management

ft:clusterId :

    - itom

bundleId :

    - itom

workflow :

    - Technology


---

# Rotate event tables and alert table cleanup

# Rotate event tables and alert table cleanup {#ariaid-title1}

* Release version: Yokohama
* 
* Updated January 30, 2025
* 
* ![](https://www.servicenow.com/docs/portal-asset/ico-clock) 1 minute to read

The growth of data tables impedes performance. Preserve instance performance by event
table rotation and alert table cleanup for status and alert history retention.

## Containing the growth of event tables {#rotate-tables-purge-data__section_p42_kkx_pz}

By default, the Event Management
event \[em_event\] table uses table rotation. The table rotation schedule ensures that new
data is written to one of the tables in the rotation group. According to the value of
Clean base rotation setting, the base table is deleted and then a
new round of writing the tables in a daily rotation commences. By default, this table
deletion occurs after seven rotations.

To back up events to a custom table, see [Event Management configuration preferences](https://servicenow-prod.fluidtopics.net/WX5uB5nhCpuS1TthTDtUZQ "Preferred settings of properties and general configuration.").

## Containing the growth of alert tables {#rotate-tables-purge-data__section_q42_kkx_pz}

By default, a scheduled job cleans out the alert \[em_alert\] table. Alert table cleanup is
recommended for status and alert history retention.
* **[Modify event table rotation](https://servicenow-prod.fluidtopics.net/9pHN0dMNUf08JsHz7Tt4jQ)**   
  Table rotation is used by Event Management, by default, to contain the growth of event \[em_event\] tables within the rotation table group.
* **[Purge impact status and alert history](https://servicenow-prod.fluidtopics.net/7umBMdiMZEd6bs3Yw4zwJg)**   
  Automatically cleans up outdated impact statuses and alert history from the database to free up space, improve system performance, and ensure only relevant data is retained.
* **[Alert table clean up](https://servicenow-prod.fluidtopics.net/UyRaO4w3xXqNsEX5ckV3Sg)**   
  The Scheduled Jobs feature runs a script to automatically close alerts in the Alerts \[em_alert\] table that meet specific conditions, helping reduce alert noise and keep the system clean and efficient.

**Related topics**   

* [Table rotation](https://www.servicenow.com/docs/access?context=c_TableRotation&version=yokohama&pubname=yokohama-platform-administration&ft:locale=en-US)