Thanks Vlad, but this is too complicated to give as a guidance to our
customers. However, it sounds like rebuilding an index cannot require more
space that the database size itself, right?

On Fri, Jun 8, 2012 at 7:22 AM, hvlad <hvlad@...> wrote:

> **
>
>
>
>
> --- In firebird-support@yahoogroups.com, Alec Swan wrote:
>
> > My main question is how can we calculate the temp sort space required
> > to ALTER INDEX ACTIVE (on all indexes serially) given the size of the
> > database? Is twice the size of the database a good upper bound?
>
> Enumerate all fields in index, calculate summa of full size of every
> field (for [var]char(N) it is N * bytes_per_char, for ex.), add extra 8
> bytes (for record number) - this is sort record size.
> Multiply it by number of records and you'll get a lower estimate of
> temp space required. Substract value of TempCacheLimit and you'll get
> estimate of disk space required.
>
> Regards,
> Vlad
>
>
>


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