mysql> SELECT @@optimizer_switch;
+------------------------------------------------------------------------------------------------------------------------+
| @@optimizer_switch
|
+------------------------------------------------------------------------------------------------------------------------+
|
index_merge=on,index_merge_union=on,index_merge_sort_union=on,index_merge_intersection=on,engine_condition_pushdown=on
|
+------------------------------------------------------------------------------------------------------------------------+
1 row in set (0.00 sec)
On Sat, Jul 7, 2012 at 8:01 PM, Peter Brawley
<peter.braw...@earthlink.net> wrote:
> On 2012-07-07 9:52 AM, Cabbar Duzayak wrote:
>>
>> Hmm,
>>
>> Looking at the link http://www.artfulsoftware.com/infotree/queries.php
>> and explanations here, EXISTS() should have performed better, but does
>> not seem to??? I stopped it after about 5 minutes.
>>
>> I tried both:
>>
>> SELECT * FROM A WHERE EXISTS (SELECT * FROM B WHERE A.id=B.A_ID and
>> B.name like 'X%');
>>
>> and
>>
>> SELECT * FROM A WHERE EXISTS (SELECT B.A_ID FROM B WHERE A.id=B.A_ID
>> and B.name like 'X%');
>>
>> Both are slow...
>
>
> What's the optimizer_switch setting?
>
> PB
>
>
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