Re: BUG #2196: Useless RECHECK on RTREE index - Mailing list pgsql-bugs

From Tom Lane
Subject Re: BUG #2196: Useless RECHECK on RTREE index
Date
Msg-id 6743.1138037164@sss.pgh.pa.us
Whole thread Raw
In response to BUG #2196: Useless RECHECK on RTREE index  ("" <agattik@gmail.com>)
List pgsql-bugs
"" <agattik@gmail.com> writes:
>  Bitmap Heap Scan on tpoints  (cost=1.05..10.46 rows=10 width=8)
>    Recheck Cond: ('(1,1),(0,0)'::box && box(point((x)::double precision,
> (y)::double precision), point((x)::double precision, (y)::double
> precision)))
>    ->  Bitmap Index Scan on i_tpoints  (cost=0.00..1.05 rows=10 width=0)
>          Index Cond: ('(1,1),(0,0)'::box && box(point((x)::double precision,
> (y)::double precision), point((x)::double precision, (y)::double
> precision)))
> (4 rows)

> The RECHECK is necessary in case of polygons, but useless in case of box
> overlap.

You don't understand what a bitmap scan's recheck condition is for.
The above plan is correct.

            regards, tom lane

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