On Fri, Sep 23, 2005 at 12:21:15PM +0200, Joost Kraaijeveld wrote:
On Fri, 2005-09-23 at 05:55 -0400, Michael Stone wrote:
It's not clear what your object id generator does. If it's just a
sequence, it's not clear that you need this program at all--just use a
SELECT INTO and make the object id a SERIAL.
It generates a GUID (and no, I do not want to turn this in a discussion
about GUIDs). As in the Java code comment: it is not the generation of
the GUID that is the problem (that is, I can generate millions of them
per second.)

I didn't say it was, did I? If you use a SELECT INTO instead of
SELECTing each record and then reINSERTing it you avoid a round trip
latency for each row. There's a reason I said "if it's just a sequence".

If you do need to control the object id or do some other processing
before putting the data into the new table, rewrite to use a COPY
instead of an INSERT.
It is actually the shortest piece of code that gives me a poor
performance. The conversion problem is much, much larger and much much
more complicated.

Ok, that's great, but you didn't respond to the suggestion of using COPY
INTO instead of INSERT.

But I have no clue where to begin with determining the bottleneck (it
even may be a normal performance for all I know: I have no experience
with converting such (large) database).

Any suggestions?

Respond to the first suggestion?

Mike Stone

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