Re: optimizing SQL's w/ multiple (and variable) range based predicates against very wide table

Hello Chris,
pretty hard to say without knowing the exact queries, the object definitions and the covered ranges by the predicates but you might want to consider index joins or just plain btree/bitmap conversion incl. OR/AND BITMAP if the queries are very volatile and got different predicates all the time.

You can still support DMLs with a lot of btree indexes but have the advantage of bitmaps (of course with the overhead of more CPU usage due to on-the-fly conversion). However please be aware that the DMLs get slower with more btree indexes but based on your description that shouldn't be a big deal here.

Best Regards
Stefan Koehler

Independent Oracle performance consultant and researcher Website: http://www.soocs.de
Twitter: _at_OracleSK

> Chris Stephens <cstephens16_at_gmail.com> hat am 25. Januar 2019 um 17:10 geschrieben:
>
>
> Oracle 12.2.0.1 3 node RAC on Centos 7.
>  
> We have a very wide table (182 columns) with ~400 million rows and a single column surrogate PK. There is very little DML against the table if any.
>  
> Most of those columns are subject to range based predicates. It is sort of a discovery table open to ad hoc SQL which makes targeted optimization a -challenge-. As you can imagine response time isn't awesome for the vast majority of SQL.
>  
> The table is currently range partitioned and sub-partitioned on 2 columns frequently used in range based filters. There are tons of local indexes.
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> I'm not sure how frequently this partitioning/indexing strategy helps vs hurts (new database to me) but after looking at a few SQL's, i don't think this helps in vast majority of cases. 
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> I'm wondering if there are any general approaches to something like this.
>  
>
> I've only just begun to look at this but my first thought is to try and figure out groups of columns that often get filtered on together and create some partitioned "skinny" tables with those columns along with the surrogate key. I think that would allow us to optimize for up to 3 range based predicates (partition, subpartition, local index) against each table and join on key. Is that sane? 
>  
> What other options are there?
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> Would inMemory help w/ something like this (we aren't currently licensed)?
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> Any feedback is greatly appreciated!
>  
> Thanks,
> Chris
>

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