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Data management tools

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Data management tools

There are a number of tools that can help manage data within the instance.

Schema Map

The Schema Map displays the relationships between tables visually, helping to navigate through the database structure.

The Schema Map provides an interface for viewing the relationships between tables. The inter-table relationships it captures include many-to-many relationships, tables that extend other tables, and tables that reference other tables through reference fields.

Data Dictionary Tables

Data dictionary tables holds information that defines the database and can be accessed for information on the database schema.

These tables hold important information on the database and its structure:

  • Tables [sys_db_object]: contains a record for each table.
  • Dictionary Entries [sys_dictionary]: contains additional details for each table and the definition for every column on each table. Each row represents either a column on a table or a table.
  • Field Labels [sys_documentation]: contains the human-readable labels and language information.

Table Cleaner

Table cleaner automatically deletes records on certain tables to prevent data growing exponentially.

ServiceNow automatically deletes records from specific tables after a specific time to deletion. Deleting these records automatically prevents the tables from growing to an unmanageable size. The time before a record is deleted begins on the date and time value in the tracked field.

The Table Cleaner scheduled job runs the table cleaner every hour. To view the list of tables that are auto-cleaned, in the Navigator filter, type:

All records with [MatchField < (current_time - Age in seconds)] are deleted.
  • The MatchField field represents a Date/Time column in the table that you are trying to clean up.
  • The Age in seconds field represents a value in seconds.
You can set up multiple table cleaner entries for a particular table. Performance depends on the size of the table and the conditions used. For example, if you use a custom column in a very large table that has no index on, performance is severely degraded. Performance also depends on the number of rows to be deleted.
Table 1. Cleaned tables
Table Tracked field Time to deletion
sys_poll sys_created_on 1 day
cmdb_metric sys_created_on 2 days
ecc_agent_metric sys_created_on 30 days
v_transaction sys_created_on 1 day
wf_context ended 180 days
sys_cache_flush sys_created_on 1 hour
sys_replication_queue sys_created_on 1 day
sysevent sys_created_on 7 days
ecc_queue sys_created_on 30 days
syslog sys_created_on 90 days
sys_querystat sys_created_on 30 days
plan_execution sys_created_on 30 days
sys_user_session last_accessed 1 day
sys_user_preference sys_updated_on 1 day
sys_history_set sys_updated_on 30 days
label_history sys_created_on 30 days
ts_search_summary sys_created_on 30 days
sys_cluster_message sys_created_on 1 day
cmdb_tcp_connection sys_updated_on 30 days
cmdb_running_process sys_updated_on 30 days