[sqlite] explain query plan showing SEARCH instead of SCAN for min/max operations

[Clemens Ladisch]

Isaac Goldberg wrote:
> I'm seeing that EXPLAIN QUERY PLAN returns SEARCH instead of SCAN when
> using min() or max(). For example:
>
> sqlite> create table t(a int, b int);
> sqlite> explain query plan select min(b) from t;
> 0|0|0|SEARCH TABLE t
>
> Why is this a SEARCH instead of a SCAN? Furthermore, is it expected that
> sometimes SEARCH can be returned with no specified index like this?

This is a side effect of the MIN/MAX optimization:
<http://www.sqlite.org/optoverview.html#minmax>

The query planner has noticed that the query itself would be eligible
for that optimization, but this is done before checking whether
a suitable index actually exists.


Regards,
Clemens