Re: Query plan and execution time of a query

If you want more precise timings then turn on log_duration_statement. 
The logs will carry timings down to the microsecond.

Also note that this is not the correct list for such questions - this 
list is about development of PostgreSQL, not use.

cheers

andrew

Kenneth Marshall wrote:
> Mickael,
>
> Not knowing your query, it sounds like your method is working
> correctly. It is quite normal to have the initial query take
> longer than subsequent queries. This is a cache effect and is
> what databases, in general, strive for performance-wise. I
> suspect that the second time you run the query that it does
> not take 0ms, just less than 1ms.
>
> Ken
>
> On Sat, Jul 21, 2007 at 03:26:19PM +0200, Mickael DELOISON wrote:
>   
>> Hello,
>>
>> I am trying to get the execution time of a query by using JDBC (Java).
>> To do that I make the difference between the time (in milliseconds)
>> after the query execution and the time before the query execution.
>>
>> The first time I do that, I get the real execution time, but the query
>> plan seems to be cached. And the next time I do the same operation,
>> for a simple query I do not get the real time (in fact  my 'simple'
>> query seems to execute in 0 millisecond).
>>
>> So I need help: I would like to solve this problem but I do not know
>> how. I have tried some researches on Internet but I did not find. Is
>> there a possibility to disable the query plan cache temporarily? It is
>> also possible I am totally wrong and the problem is not where I see
>> it... Anyway I need help.
>>
>> Thank you in advance,
>> Mickael
>>
>> ---------------------------(end of broadcast)---------------------------
>> TIP 9: In versions below 8.0, the planner will ignore your desire to
>>       choose an index scan if your joining column's datatypes do not
>>       match
>>
>>     
>
> ---------------------------(end of broadcast)---------------------------
> TIP 5: don't forget to increase your free space map settings
>
>