[OSM-dev] rails schema + mysql on dev v slow

SteveC steve at asklater.com
Tue May 15 22:10:44 BST 2007


On 15 May 2007, at 21:29, Lars Aronsson wrote:

> SteveC wrote:
>
>> visible:
>>
>> 1 = there
>> 0 = deleted
>> none returned = not created yet
>
> Is there any difference, performance-wise if instead we'd have
> NULL = deleted ?  AFAIK, NULL doesn't get indexed, so the index
> might be smaller.  You could then not use the index for finding
> the deleted records, but do we ever use it for that?

No, I don't think an index on visible is used at all. In any case  
mysql won't use indexes on boolean columns as I found out doing the  
tile stuff.

>
>
>
> -- 
>   Lars Aronsson (lars at aronsson.se)
>   Aronsson Datateknik - http://aronsson.se
>
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have fun,

SteveC | steve at asklater.com | http://www.asklater.com/steve/






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