Re: postgresql Explain command output

How do we know in the output of expain command table or constraint names
so that while parsing each line of the output
we can able to recognise them and build the pictorial representation. for
example if you consider the following output

EXPLAIN select * from table1,table2 where roll=id_no;
QUERY PLAN
----------------------------------------------------------------------
Hash Join (cost=29.12..59.31 rows=850 width=124)
Hash Cond: (table2.id_no = table1.roll)
-> Seq Scan on table2 (cost=0.00..18.50 rows=850 width=62)
-> Hash (cost=18.50..18.50 rows=850 width=62)
-> Seq Scan on table1 (cost=0.00..18.50 rows=850 width=62)

we can know the table name , just by seeing any string after ON
keyword . Like that how to recognise the other constraints and so on.

On Thu, Mar 6, 2008 at 12:24 PM, Devi <devi(at)visolve(dot)com> wrote:

> Hi,
>
> I suppose the format depends on the query you serve. The following links
> will throw some light.
>
> http://www.postgresql.org/docs/8.1/static/sql-explain.html
> http://www.postgresql.org/docs/7/static/c4888.htm
>
> Thanks
> DEVI.G
>
> ----- Original Message -----
> *From:* RaviRam Kolipaka <raviram(dot)kolipaka(at)gmail(dot)com>
> *To:* pgsql-performance(at)postgresql(dot)org
> *Sent:* Thursday, March 06, 2008 11:40 AM
> *Subject:* [PERFORM] postgresql Explain command output
>
>
> hi,
>
> is there any generalized format for the output for the output of the
> explain command ?. If so please send that generalized format to me.
> otherwise tell me how to parse the output of explain command to
> know where the relation name occurs,where the conditions occurs,
> where the join conditions occur and so on. My goal is create a visual
> representation of the expain plan. Can some body help me in this regard.
> Thanks & regards
> RAVIRAM KOLIPAKA
> M.TECH(CSE)-final year
> IIIT Hyderabad
>
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