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From Rick Hillegas <rick.hille...@gmail.com>
Subject Re: Database maintenance routines
Date Tue, 05 Nov 2019 13:57:00 GMT
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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