Is it possible to calculate projected space gain after INDEX REBUILD?

  • Folks,

    From my experience, rebuilding indexes (while might require addition space to be done), frees up (sometimes a lot of) space after the procedure is completed.

    My question is: Is there a way to know exactly (or approximately) how much space will be regained after the REBUILD INDEX is done with [i.e. without performing the actual REBUILD INDEX]?

    Thanks a lot!

  • Did you try sp_spaceused before and after reindexing?

    I am not sure your statement of rebuildindex. Could you explain why the process release space?

    Many thanks in advance.

  • I meant that I did not rebuild the index yet. I would like to know (before rebuilding) what would be the gain in space if I actually do rebuild.

    The reason behind it is that I have a 30 GB table with a clustered index, which I would like to rebuild. However, I believe it would take a long time and there will a downtime. Therefore, before I go ahead with it, I want to know the projected space gain, so that I can weigh this against the down time and make the final decision.

    And the reason for wanting to gain space is that our backups have been growing (currently at 50GB) and we never rebuilt indexes, and I know we can free up much space if we do rebuild indexes.

    Thanks!

  • I can see one possiblility of releasing space while rebuilding indexes if there is some updtion(deletion) happen and data pages have free space or while rebuiling indexes fill factor is changes then space may be released .

  • Hmm ... maybe my question is not clear enough.

    I want to PREDICT how much space I can gain by rebuilding indexes.

    I don't want to do REBUILD them ... I want to know without (or before) REBUILDING them.

    Sorry for confusion.

    Thanks!

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