Re: Row estimates off by two orders of magnitude with hstore

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On 06/10/2015 11:32 AM, Merlin Moncure wrote:
> This is a fundamental issue with using 'database in a box' datatypes
> like hstore and jsonb.  They are opaque to the statistics gathering
> system and so are unable to give reasonable estimates beyond broad
> assumptions.  Speaking generally, the workarounds are too:
> 
> *) disable particular plan choices for this query
> (materialize/nestloop are common culprits)
> 
> *) create btree indexes around specific extraction clauses
> 
> *) refactor some of the query into set returning function with a
> custom ROWS clause
> 
> *) try alternate indexing strategy such as jsonb/jsquery
> 
> *) move out of hstore and into more standard relational strucure

You forgot:

*) Fund a PostgreSQL developer to add selectivity estimation and stats
to hstore.

-- 
Josh Berkus
PostgreSQL Experts Inc.
http://pgexperts.com


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