[colug-432] Bash fun

[Tom Hanlon]

Hey everybody,

Thanks.

Perhaps I was not completely clear, but I have made progress and  
should be able to solve this in the next round of rewrite.

I want to take a file containing queries, append the word "explain" to  
each line , then capture the output, but only tab 3 and tab 6 of a tab  
delimited file.

So a little more than batching mysql input.. but not all that much  
more..

So basically read file, rewrite line | mysql | cut -f 3,6 >>file

--
Tom
On 1 Nov 2009, at 15:14, Stephen P Potter wrote:

> Tom Hanlon wrote:
>> Thanks Matt,
>>
>> Good to know that eval is not needed.
>>
>> Another question, suppose I wanted to throttle this script.
>>
>> I want to run only 10 requests for second ?
>>
>> Part of the issue is this will spawn one mysql connection per line.
>>
>> The connection will be immediately dropped but we would still face:
>> 	authentication, thread generation , execution , disconnect.
>> 	authentication, thread generation , execution , disconnect.
>> 	authentication, thread generation , execution , disconnect.
>>
>> Rather than.
>> 	authentication, thread generation
>> 		execution
>> 		execution
>> 		execution
>> 		......
>> 	disconnect
>> 		
>>
>>
>>
>>
>> Unfortunate but I do not know how to batch explain from inside mysql.
>>
>> MySQL does take batch jobs as  source.sql > mysql >>outfile.txt
>>
>> So I might try and work it that way.
>>
>> Batch 100 lines, connect and run,
>>
>> Batch 100 lines, connect and run.
>>
>> If I find I have to run this on a production box.. well it would  
>> be  nice to not spawn one mysql connection per line.
>>
> You said your are taking all your input from a pre-existing file,  
> correct?  In that case, the batch nature of mysql means that each  
> query will be run sequentially in a single connection to the  
> database.  It doesn't make any significant different to batch 100 at  
> a time versus running them all sequentially (unless you really mean  
> batch; sleep; batch; sleep; batch).  Also, you want either "cat  
> source.sql | mysql" or "mysql < source.sql" not "source.sql >mysql".
>
> -spp