Re: in-memory option

On Wednesday, June 11, 2014 1:15:46 AM UTC-4, vsevolod afanassiev wrote:
> Not much new info in the presentation by Larry Ellison compared with the Open World presentation. It would be nice to know:
>
> - how much the In-Memory Option will cost - I assume it will be separately licensed option like Partitioning
>
> - how to estimate size of a table in compressed columnar format
>
> - what happens if a table grows and no longer fits in memory?
>
> - how long it takes to populate the in-memory columnar tables after database restart
>
> - the columnar in-memory store - is it going to be re-sized by automatic shared memory management? or it will remain static?
>
> - in all the 'real-life' examples - did they compare performance on the server with the same amount of memory? Or they added memory for the In-Memory Option?

Disclaimer: I don't work for Oracle; so I can't answer questions like cost, licensing and if a specific feature will work exactly that way when the production version comes. Please consider my responses with that background.

> - how to estimate size of a table in compressed columnar format

Exact space depends on the types of compression. There is an estimate function available to estimate the space usage, very similar to the space usage in Hybrid Columnar Compression.  

> - what happens if a table grows and no longer fits in memory?

No worries. Remember, this is an *additional* cache; not a replacement. The table will be subject to the same approach as in a non-InMem option database. Besides, you may not want to put all the tables in InMem store. Those not in there will be subjet to the old behavior.

> - how long it takes to populate the in-memory columnar tables after database restart

Depends on the table size. You will be able to see the amount loaded and percentage remaining. In my tests I saw a 1 TB column store getting loaded in 1 hour. YMMV.

> - the columnar in-memory store - is it going to be re-sized by automatic shared memory management? or it will remain static?

No; it's different from ASMM.

> - in all the 'real-life' examples - did they compare performance on the server with the same amount of memory? Or they added memory for the In-Memory Option?

I did not add memory; I removed it from the buffer cache to give it to the InMem cache.

Thanks.

Arup Nanda
_at_ArupNanda
arup.blogspot.com Received on Wed Jun 11 2014 - 18:50:09 CEST