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From "Alex O'Ree" <alexo...@apache.org>
Subject Re: Database maintenance routines
Date Tue, 05 Nov 2019 21:18:05 GMT
Perfect, thanks

On Tue, Nov 5, 2019 at 8:57 AM Rick Hillegas <rick.hillegas@gmail.com>
wrote:

> On 11/5/19 4:03 AM, Alex O'Ree wrote:
> > I have a use case where by I add a bunch of rows, export then in an
> > archive, then delete all the rows and repeat for weeks or months on end.
> > Are there any maintenance procedures I should be running after each
> purge?
> >
> > Postgres and mssql has some functions to tell it to recover disk space
> and
> > compact itself, or to notify that there was a large change in row volume.
> > Is there anything like this in derby?
> >
> I would recommend using TRUNCATE TABLE to delete all the rows of the
> table. This should be fast and it will re-initialize the table with an
> empty backing file.
>
> In general, you can use the SYSCS_UTIL.SYSCS_COMPRESS_TABLE system
> procedure to squeeze unused space out of a table. You can use
> SYSCS_UTIL.SYSCS_UPDATE_STATISTICS to regenerate the histograms which
> the optimizer uses in order to calculate optimal query plans.
>
> See the Derby Reference Manual for information on these commands.
>
> Hope this helps,
> -Rick
>
>

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