John A Meinel <[EMAIL PROTECTED]> writes:
> Joel Fradkin wrote:
>> Postgres was on the second run
>> Total query runtime: 17109 ms.
>> Data retrieval runtime: 72188 ms.
>> 331640 rows retrieved.

> How were you measuring "data retrieval time"?

I suspect he's using pgadmin.  We've seen reports before suggesting that
pgadmin can be amazingly slow, eg here
where the *actual* data retrieval time as shown by EXPLAIN ANALYZE
was under three seconds, but pgadmin claimed the query runtime was 22
sec and data retrieval runtime was 72 sec.

I wouldn't be too surprised if that time was being spent formatting
the data into a table for display inside pgadmin.  It is a GUI after
all, not a tool for pushing vast volumes of data around.

It'd be interesting to check the runtimes for the same query with
LIMIT 3000, ie, see if a tenth as much data takes a tenth as much
processing time or not.  The backend code should be pretty darn
linear in this regard, but maybe pgadmin isn't.

                        regards, tom lane

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