Re: Internal operations when the planner makes a hash join. - Mailing list pgsql-performance

From Kevin Grittner
Subject Re: Internal operations when the planner makes a hash join.
Date
Msg-id 4B840A5B020000250002F599@gw.wicourts.gov
Whole thread Raw
In response to Re: Internal operations when the planner makes a hash join.  (negora <negora@negora.com>)
List pgsql-performance
>negora <negora@negora.com> wrote:

> I even might return the entire result to my external Java
> application

You are probably going to want to configure it to use a cursor, at
least if the result set is large (i.e., too big to cache the entire
result set in memory before you read the first row).  Read this over
carefully:

http://jdbc.postgresql.org/documentation/84/query.html#query-with-cursor

You don't have to use a Java cursor or do anything procedurally
there, but a PostgreSQL cursor is the only way to stream the data to
the application on demand (ResultSet.next), rather than pushing it
all there during the Statement.execute().

-Kevin

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