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Design question regarding arrays
comp.databases.postgresql.novice comp.databases.postgresql.novice
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#11
 
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Re: Design question regarding arrays -
08-09-2004
, 05:26 AM
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I'm a novice, too, but why not look up the value in the sequence and increment it before doing any inserting? If you are doing all the inserts at the same time (more or less), then you can just use this value in the insert into both tables. Put all of this inside one transaction. |
being transaction safe, currval is session safe (correcting something I
said in an earlier post). As long as you don't put another insert or
otherwise manipulate the sequence in the same session, you can trust
currval
Michael Glaesemann
grzm myrealbox com
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#12
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I'm a novice, too, but why not look up the value in the sequence and increment it before doing any inserting? If you are doing all the inserts at the same time (more or less), then you can just use this value in the insert into both tables. Put all of this inside one transaction. |
thing at the same time. They both get the same value when
they look it up, so there will be an ID collision.
Best regards
Oliver
--
Oliver Fromme, secnetix GmbH & Co KG, Oettingenstr. 2, 80538 München
Any opinions expressed in this message may be personal to the author
and may not necessarily reflect the opinions of secnetix in any way.
"Being really good at C++ is like being really good
at using rocks to sharpen sticks."
-- Thant Tessman
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#13
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Sean Davis wrote: I'm a novice, too, but why not look up the value in the sequence and increment it before doing any inserting? If you are doing all the inserts at the same time (more or less), then you can just use this value in the insert into both tables. Put all of this inside one transaction. That won't work if another process is trying to do the same thing at the same time. They both get the same value when they look it up, so there will be an ID collision. |
the value that you are using in both insert statements. A second session
will not get the same value you just got from nextval barring a cycling
sequence generator that wraps back to the same number between the nextval
and insert.
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#14
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On Mon, 9 Aug 2004, Oliver Fromme wrote: Sean Davis wrote: I'm a novice, too, but why not look up the value in the sequence and increment it before doing any inserting? If you are doing all the inserts at the same time (more or less), then you can just use this value in the insert into both tables. Put all of this inside one transaction. That won't work if another process is trying to do the same thing at the same time. They both get the same value when they look it up, so there will be an ID collision. It should be safe if you're using a sequence and using nextval() to get the value that you are using in both insert statements. A second session will not get the same value you just got from nextval barring a cycling sequence generator that wraps back to the same number between the nextval and insert. |
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