Re: Difference in temp table insert performance

The large number of combined reads and writes to temp on in a LOAD operation suggest two possibilities (though I've not seen the pattern before).

1. maybe the statistics are actually being reported in the wrong place in the plan for some reason
2. possibly the code is doing something with LOB columns - perhaps if it was calling a function in the select list that concatenates a number of values to construct a LOB value this is one of the side effects.

Look at the SQL, the column definitions, and the projection information - that might give you some clues.

BTW - what is the FILTER operation doing ?

Regards
Jonathan Lewis

On Fri, 7 Jan 2022 at 17:15, Pap <oracle.developer35_at_gmail.com> wrote:

> Hello Listers, Its version 11.2.0.4 of Oracle. And is planned to move to
> 19C soon.
>
> For one of the third party applications , we see direct path insert into
> the global temporary temp table is taking significant time. Below is sql
> monitor from two of the queries , both of them are loading data into global
> temporary tables and in the first case it's inserting ~500million and in
> second case it's inserting ~700million rows. But what we see is even the
> first case global temporary table holds no indexes in it , it's still
> showing ~84% of the activity in the data load step(plan_line_id - 1). And
> the activity section in the sql monitor showing significant time samples
> for 'direct path read temp' and 'direct path write temp'.
>
> In the second case it's inserting ~747million rows but is not spending
> that much time in the data load part i.e. plan_line_id-1 and also i am not
> seeing those 'direct path read temp' and 'direct path write temp' samples
> there. Even this global temporary has 3- indexes in it.
>
> So we wanted to understand what must be causing this ? and if we could
> make the data load into the global temporary table faster in the first
> case? In the second case I understand it's the HASH join part where we are
> spending a lot of time as it spills to temp and we may not have much option
> at hand but we were expecting at least the data load should not take this
> amount of time.
>
>

--
http://www.freelists.org/webpage/oracle-l