Re: How does Oracle determine how much to extend autoextend datafiles?

On 2019/03/14 12:40, Chris Taylor wrote:

> I just thought the extent management in Oracle in LMT - depending on the size of the segment, Oracle auto determines the next extent size when using automatic space management.
>
> So depending on the size of the segments involved (table, indexes, lobs(?) ) those next extents might have been large.
>
> I think I saw an Oracle support document on the extent size thresholds (based of segment_size) but I can't lay my hands on it at the moment.

I'd agree that the algorithm might make the next extent "large", but the new extent(s) totaled less than 2GB. Which is why I'm curious what was going on that the TS grew by exactly 31GB.

After verifying the top used block in each datafile, I resized them. Sure enough, I got back about 28GB of unused/unallocated space. The ERP that uses this DB doesn't add/drop segments on-the-fly or anything like that. The only event that I can see where the datafiles would autoextend is segment growth. And there's a 28+GB difference between how much the segment(s) grew and how much the TS grew. Weird.

Thanks for the feedback, Chris!

Rich

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