Re: Operator class group proposal

Tom Lane <tgl@sss.pgh.pa.us> writes:

> No, what you'll get is something like
> 
>     int4var::float8 float8eq float8var
> 
> which is perfectly mergejoinable ... however, it's not clear that the
> planner will make very good estimates about the value of the cast
> expression.  I'm not sure if it's worth introducing a pile more
> crosstype operators to change that situation --- improving
> the selectivity functions to handle casts better might be a wiser
> approach.

So the only reason we needed the cross-data-type operators was to get better
estimates? I thought without them you couldn't get an index-based plan at all.

--  Gregory Stark EnterpriseDB          http://www.enterprisedb.com