Re: Bulk row fetching

From: Joe Conway <mail(at)joeconway(dot)com>
To: Carmen Wai <wai_carmen(at)hotmail(dot)com>
Cc: kleptog(at)svana(dot)org, pgsql-general(at)postgresql(dot)org
Subject: Re: Bulk row fetching
Date: 2002-08-15 15:42:51
Message-ID: 3D5BCBFB.10205@joeconway.com
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Carmen Wai wrote:
>
> I want to implement a similar mechanism as bulk row fetching in MFC ODBC
> classes for postgresql. For the very large record sets, it can fetch the
> first (let say) 100 records. After that, it can automatically fetch the
> next 100 records WITHOUT executing the SQL statement again, it will save
> lots of memory resouce / time.
>
> I only find that postgresql support : select * from table_name limit N
> offset M, but if I do it in this way, the DB need multiple execution
> which will take up lots of time.
>
> Do anyone gets any idea?

It always helps to start with the manual ;-)

See:
http://www.postgresql.org/idocs/index.php?libpq-example.html
for an example which uses a cursor. Instead of "FETCH ALL in mycursor",
you can do something like "FETCH 100 in mycursor". See:
http://www.postgresql.org/idocs/index.php?sql-fetch.html
for more on FETCH. See:
http://www.postgresql.org/idocs/index.php?sql-declare.html
for more on declaring a cursor.

HTH,

Joe

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