Skip to main content
Waters

Why does the Oracle Database not shrink when data is exported and deleted? - WKB230557

Article number: 230557

ENVIRONMENT

  • UNIFI
  • waters_connect

ANSWER

  • Oracle Databases consist of data files that increase in size as data is added.
  • Each data file is set with a quota, the maximum size to which it will grow.
  • When data is deleted the data file remains the same size, but space becomes available for new data.
  • For this reason, the space available cannot be viewed in Windows Explorer (for a workstation).

    Workstation example:
  • Up to 200 data files of 20GB are created as required (about 4TB).
  • If 1TB of data is exported to uep and folders deleted from a 4TB database, it will still have 200 data files, but there will be 1TB of free space for acquiring new data.

    Server example:
  • One large data file is stored in Oracle ASM and is typically set to grow to about 70% of the Full ASM Disk Group, typically 10TB.
  • So, if the database reaches 7TB, the max size or quota can be adjusted to a higher value, such as 9TB.
  • If the database then reaches 9TB, deleting 1TB of data will not reduce the size of the data file but will free 1TB of space for newly acquired data.

Note: It is important to understand that backup sizes are always based on the size of the datafile and that empty space is still backed up. For this reason it is not recommended to keep increasing the size of the database storage because backups will also need more storage and become unmanageable in terms of space and time taken to complete.

 

ADDITIONAL INFORMATION

 

id230557, SUPUNIFI, UNIFISVR, UNIFISW18, UNIFOPT, UNIFQLIC, UNIFSW17, UNIFSW18, UNIFSW19, UNIFWGLIC, UNIFWKLIC

Not able to find a solution? Click here to request help.