IDS Forum

BUFFERS - A question

Posted By: rkusenet
Date: Wednesday, 22 January 2003, at 10:48 a.m.

I apologize if this is too stupid a question.

If I issue this command:-

unload to ...
select * from ...

does the server transfer the data from the table to the BUFFER.
AFAIK the server first reads the data into the BUFFER and then
performs any operations on it, even if it is SELECT only.
The only exception is HPL light read which I believe reads
directly from the extents bypassing BUFFERS.

I need to understand this correctly for the following scenario.

We are debating whether to download few tables during peak hours
or off peak hours. These tables are large tables and are downloaded
to pipe delimited format using the above mentioned command in
dbaccess. My concern is that this should not fill out BUFFERS,
which will then force other data from BUFFERS to be swapped
out, degrading performance.

While we are at it, if while scanning data from a table , the
server comes across empty pages, does the empty page get loaded
in BUFFERS. I believe Oracle loads it into the BUFFERS and only
then it is determined that it is empty.

thanks.

ravi

Messages In This Thread

• BUFFERS - A question
  rkusenet -- Wednesday, 22 January 2003, at 10:48 a.m.
  • Re: BUFFERS - A question
    Jack Parker -- Wednesday, 22 January 2003, at 5:08 p.m.

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