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From:Alex Schaft Date:February 9 2012 12:33pm
Subject:Re: C api mysql_store_result vs mysql_use_result
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On 2012/02/09 01:40 PM, Johan De Meersman wrote:
> ----- Original Message -----
>> From: "Alex Schaft"<alexs@stripped>
>>
>> If I were to do a select count(*) from x where y prior to doing
>> select * from x where y to get a number of records, how would this impact
>> performance on the server itself? Would the first query be the one to
>> do the most processing, with the second one being faster, or would both
>> have to do the same amount of work?
> Heh. The amount of work put into parsing and executing would be the same, except if
> you can compose your count query to use only indexed fields.
>
> Easily checked with an explain of both queries, I'd say.
>
> Also, do consider if you really need a %complete progress indicator, or if a simple
> record counter with no indicated endpoint will do. That is, do your users need to know how
> long it's going to take, or do they just want assurance that the process didn't hang?
>
>
 From the user's perspective, they just need to know the process didn't 
hang. The count() query is more for getting memory requirements upfront. 
Can I handle it all, or do I need to break it down into pages?

Thread
C api mysql_store_result vs mysql_use_resultAlex Schaft9 Feb
  • Re: C api mysql_store_result vs mysql_use_resultJohan De Meersman9 Feb
    • Re: C api mysql_store_result vs mysql_use_resultAlex Schaft9 Feb
      • Re: C api mysql_store_result vs mysql_use_resultJohan De Meersman9 Feb