Re: [HACKERS] seq scan only when function not in subquery (bug?)

Brett McCormick wrote:
>
> sas=> explain update user set usrid = 'aaaaaaaa'
> where usrseqid=usrseqid('zlb');
>
> NOTICE:  QUERY PLAN:
>
> Seq Scan on user  (cost=344.07 size=658 width=154)

...

> as you can see, it uses the index when the RHS of the comparison
> in the where clause is a subquery, but a sequential scan when it
> isn't.  is this a bug?

Yes, and very old :)

This is from my recent posting:
---
Another issue - handling of functions with constant args
in queries - for query

select * from T where A = upper ('bbb')

function upper ('bbb') will be executed for each tuple in T!
More of that - if there is index on T(A) then this index will
not be used for this query!
Obviously, upper ('bbb') should be executed (by Executor, not
parser/planner) once: new Param type (PARAM_EXEC) implemented
for subselects could help here too...
---

Actually, this is easy to fix...

Vadim