From: Rajesh Kumar Mallah <mallah@trade-india.com>
Organization: Infocom Network Limited
To: Popeanga Marian <pmarian@cnlo.ro>
Subject: Re: explain
Date: Fri, 21 Mar 2003 17:40:27 +0530
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Cc: Roberto Mello <rmello@cc.usu.edu>, pgsql-sql@postgresql.org
References: <3E7AA719.2090507@cnlo.ro> <3E7ACD00.6050702@cnlo.ro>
	<3E7AF0CD.10103@cnlo.ro>
In-Reply-To: <3E7AF0CD.10103@cnlo.ro>
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Hi,


Marian i am not too familiar with oracle features.

Can you tell us the problem you are trying to solve.

lemme try to understand the below.

> > In Oracle i will do:
> > explain plan set statement_id=uniq_id_for_select for  
> >                 select * from dba_tables where table_name=:tab


what does it do ?
assigning a uniq_id to the query "select * from dba_tables where table_name=:tab"
is the query an example query or a fixed method of accomplising something?


> >
> > SELECT * FROM plan_table WHERE Statement_ID = this_uniq_id_for_select;
> >

is plan_table supposed to store execution plans of all the  queries being
executed by dbserver , or only certain queries you are marking by 
some mechanism?

In case you are wanting to see the execution plan and query times of each and every
query there is a crude method.

(DISCLAIMER: the opinions are mine and does not reflects others')

enable logging to appropriate levels , postmaster can log execution plans
and timings in a file.
you will find more details in Admin Docs.

Regds
mallah.


On Friday 21 Mar 2003 4:30 pm, Popeanga Marian wrote:
> 
> 
> Popeanga Marian wrote:
> 
> > Thanks for your repply.
> >
> >         This is what i expected too.  Can you point me from where i 
> > can get this result ?
> >
> > explain select * from pg_tables where tablename=:tab;
> >
> >
> > select * from ... ?
> >
> >
> >
> >
> >
> I need this at programming level, not from within pgsql tool.
> I tryed directly with explain select ... but it doesn't retrive any tuples!
> 
> >
> > Rajesh Kumar Mallah wrote:
> >
> >>Dear Marian,
> >>
> >>in postgresql 7.3 explain commands retruns as
> >>set of rows.
> >>
> >>The result of EXPLAIN can just be fecthed as result
> >>of any other SELECT query and manipulated further.
> >>
> >>i hope it helps.
> >>
> >>sorry if i did not get ur problem rite.
> >>
> >>
> >>regds
> >>mallah.
> >>
> >>
> >>
> >>
> >>On Friday 21 Mar 2003 11:51 am, Popeanga Marian wrote:
> >>  
> >>
> >>>Roberto Mello wrote:
> >>>
> >>>    
> >>>
> >>>>On Fri, Mar 21, 2003 at 07:46:01AM +0200, Popeanga Marian wrote:
> >>>> 
> >>>>
> >>>>      
> >>>>
> >>>>>Hello all,
> >>>>>
> >>>>>
> >>>>>          Can someone point me how can i make explain plan for a query?
> >>>>>   
> >>>>>
> >>>>>        
> >>>>>
> >>>>explain select blah from foo where bar = baz;
> >>>>
> >>>>\h explain
> >>>>
> >>>>Look at the PostgreSQL documentation (SQL Reference).
> >>>>
> >>>>-Roberto
> >>>>
> >>>> 
> >>>>
> >>>>      
> >>>>
> >>>   I have look at this command. I want to know how can i make this from 
> >>>other tool than pgsql.
> >>>In oracle when i issue an explain plan the explain insert values into a 
> >>>table ( plan_table ).
> >>>Then i could select the values from plan_table.         Is there similar 
> >>>in postgres ?
> >>>
> >>>-- 
> >>>Popeanga Marian
> >>>DBA Oracle
> >>>CNLO Romania
> >>>
> >>>
> >>>
> >>>    
> >>>
> >>
> >>  
> >>
> >
> >-- 
> >Popeanga Marian
> >DBA Oracle
> >CNLO Romania
> >  
> >
> >
> 
> -- 
> Popeanga Marian
> DBA Oracle
> CNLO Romania
> 
> 
> 

-- 
Rajesh Kumar Mallah,
Project Manager (Development)
Infocom Network Limited, New Delhi
phone: +91(11)6152172 (221) (L) ,9811255597 (M)

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