Re: WHERE clause OR vs IN

["Medi Montaseri" <montaseri@xxxxxxxxx>]

Thanks...is'nt the run time latency more visiable with lorge input sets (big tables) as well as how long the OR-ed _expression_ chain is

based on your report, run time of OR is 0.275 ms and IN is 0.314

Perhaps if we run explain verbose to see the actual query plan

medi

On Dec 12, 2007 2:36 PM, Joshua D. Drake <jd@xxxxxxxxxxxxxxxxx> wrote:

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On Wed, 12 Dec 2007 14:25:16 -0800
"Medi Montaseri" <montaseri@xxxxxxxxx > wrote:

> Hi,
>
> I know this is not exactly admin related, but ... it is simple enough
> to be even fun
>
> From a performance point of view, is it better to use OR as in
> SELECT expr FROM expr WHERE col=this OR col=that OR col=theOther
> Or to use a range of values as in
> SELECT expr FROM expr WHERE col in ( val1, val2, ...., valn)
>
> I think the IN range yields a better query plan .... what do you
> think ? Thanks

Well a simple test:

postgres=# explain analyze select * from tellers where bid in ('1','2');
                                             QUERY
PLAN
- ------------------------------------------------------------------------------------------------------
Seq Scan on tellers  (cost=0.00..10.25 rows=20 width=352) (actual
time=0.019..0.192 rows=20 loops=1) Filter: (bid = ANY
('{1,2}'::integer[])) Total runtime: 0.314 ms (3 rows)

postgres=# explain analyze select * from tellers where bid = '1' or bid
= '2'; QUERY PLAN
- ------------------------------------------------------------------------------------------------------
 Seq Scan on tellers  (cost=0.00..11.50 rows=20 width=352) (actual
time=0.018..0.199 rows=20 loops=1) Filter: ((bid = 1) OR (bid = 2))
 Total runtime: 0.275 ms
(3 rows)

postgres=#



> Medi


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