Re: COPY and heap_sync - Mailing list pgsql-hackers

From Amit Kapila
Subject Re: COPY and heap_sync
Date
Msg-id CAA4eK1Ke7+872kFsBSHYFYy8E=Lv1d19wAt0gwQjTvabFZQ=TQ@mail.gmail.com
Whole thread Raw
In response to COPY and heap_sync  (Jeff Janes <jeff.janes@gmail.com>)
Responses Re: COPY and heap_sync
List pgsql-hackers
On Sat, Aug 30, 2014 at 11:56 AM, Jeff Janes <jeff.janes@gmail.com> wrote:
>
> If you insert tuples with COPY into a table created or truncated in the same transaction, at the end of the COPY it calls heap_sync.
>
> But there cases were people use COPY in a loop with a small amount of data in each statement.  Now it is calling heap_sync many times, and if NBuffers is large doing that gets very slow.
>
> Could the heap_sync be safely delayed until the end of the transaction, rather than the end of the COPY?

Wouldn't unconditionally delaying sync until end of transaction
can lead to burst of I/O at that time especially if there are many
such copy commands in a transaction, leading to delay in some
other operation's that might be happening concurrently in the
system.


With Regards,
Amit Kapila.
EnterpriseDB: http://www.enterprisedb.com

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