Re: Index Skip Scan

Hi Floris,

On 6/1/19 12:10 AM, Floris Van Nee wrote:
> Given a table definition of (market text, feedcode text, updated_at timestamptz, value float8) and an index on
(market,feedcode, updated_at desc) (note that this table slightly deviates from what I described in my previous mail)
andfilling it with data.
 
> 
> 
> The following query uses an index skip scan and returns just 1 row (incorrect!)
> 
> select distinct on (market, feedcode) market, feedcode
> from streams.base_price
> where market='TEST'
> 
> The following query still uses the regular index scan and returns many more rows (correct)
> select distinct on (market, feedcode) *
> from streams.base_price
> where market='TEST'
> 
> 
> It seems that partially filtering on one of the distinct columns triggers incorrect behavior where too many rows in
theindex are skipped.
 
> 
> 

Thanks for taking a look at the patch, and your feedback on it.

I'll def look into this once I'm back from my travels.

Best regards,
  Jesper