in this particular app, we were registering new users and the pk didn't need to be returned (email address was a unique field).
--- Stefan Jahnke <[EMAIL PROTECTED]> wrote: > Hi Rachel > > In most Java applications I've seen so far, the issue of caching rows > by an > id, which is usually the primary key, arises. JDBC v3 implements a > method > which allows you to return a key after the insert completed (for > example MS > SQL Server can do this). How do you get a hold of the PK, after you > inserted > the key via trigger without an extra roundtrip ? > > Regards, > Stefan > > -----Urspr�ngliche Nachricht----- > Von: Rachel Carmichael [mailto:[EMAIL PROTECTED] > Gesendet: Mittwoch, 5. November 2003 14:34 > An: Multiple recipients of list ORACLE-L > Betreff: Re: How do you genrate primary keys? > > > At one site I worked at, the programmers insisted on using Java > milliseconds as the primary key -- so that they wouldn't have to hit > the database twice (once to get the sequence number, once to insert > the > row). They swore up, down and six ways from Sunday that there could > never, ever, EVER be a collision. > > After we had collisions in development, we switched to sequences (one > per table), with a trigger to populate the field on insert so that > they > wouldn't have to make the second round-trip. > > > --- Jonathan Gennick <[EMAIL PROTECTED]> wrote: > > The recent article that mentioned sequences got me to > > thinking. I might pitch a more detailed article on sequences > > to Builder.com. But a more interesting article might be one > > that explored various ways to automatically generate primary > > keys. So, in the name of research, let me throw out the > > following questions: > > > > What mechanisms have you used to generate primary keys? > > Which ones worked well, and why? Which mechanisms worked > > poorly? > > > > I've run up against the following approaches: > > > > * Hit a table that keeps a counter. This is the "roll your > > own sequence method". The one time I recall encountering > > this approach, I helped convert it over to using stored > > sequences. This was because of concurrency problems: with > > careful timing, two users could end up with the same ID > > number for different records. Is there ever a case when this > > roll-your-own approach makes sense, and is workable? > > > > * Stored sequences. I worked on one app that used a separate > > sequence for each automatically generated primary key. I > > worked on another app, a smaller one, that used the same > > sequence for more than one table. The only issue that I > > recall is that sometimes numbers would be skipped. But end > > users really didn't care, or even notice. > > > > * The SYS_GUID approach. I've never used SYS_GUID as a > > primary key generator. I wonder, was that Oracle's > > motivation for creating the function? Has anyone used it for > > primary keys in a production app? What's the real reason > > Oracle created this function? > > > > * Similar to SYS_GUID, I once worked on an obituary-tracking > > application that built up a primary key from, as best I can > > recall now: date of death, part of surname, part of first > > name, and a sequence number used only to resolve collisions, > > of which there were few. The approached worked well, > > actually, because whatever fields we munged together to > > generate a primary key gave us a unique key the vast > > majority of the time. > > > > The SYS_GUID approach is interesting, but if you need an ID > > number that users will see, and that users might type in > > themselves (e.g. social security number), is SYS_GUID really > > all that viable? > > > > Best regards, > > > > Jonathan Gennick --- Brighten the corner where you are > > http://Gennick.com * 906.387.1698 * mailto:[EMAIL PROTECTED] > > > > Join the Oracle-article list and receive one > > article on Oracle technologies per month by > > email. To join, visit > > http://four.pairlist.net/mailman/listinfo/oracle-article, > > or send email to [EMAIL PROTECTED] and > > include the word "subscribe" in either the subject or body. > > > > -- > > Please see the official ORACLE-L FAQ: http://www.orafaq.net > > -- > > Author: Jonathan Gennick > > INET: [EMAIL PROTECTED] > > > > Fat City Network Services -- 858-538-5051 http://www.fatcity.com > > San Diego, California -- Mailing list and web hosting > services > > > --------------------------------------------------------------------- > > To REMOVE yourself from this mailing list, send an E-Mail message > > to: [EMAIL PROTECTED] (note EXACT spelling of 'ListGuru') and in > > the message BODY, include a line containing: UNSUB ORACLE-L > > (or the name of mailing list you want to be removed from). You may > > also send the HELP command for other information (like > subscribing). > > > __________________________________ > Do you Yahoo!? > Protect your identity with Yahoo! Mail AddressGuard > http://antispam.yahoo.com/whatsnewfree > -- > Please see the official ORACLE-L FAQ: http://www.orafaq.net > -- > Author: Rachel Carmichael > INET: [EMAIL PROTECTED] > > Fat City Network Services -- 858-538-5051 http://www.fatcity.com > San Diego, California -- Mailing list and web hosting services > --------------------------------------------------------------------- > To REMOVE yourself from this mailing list, send an E-Mail message > to: [EMAIL PROTECTED] (note EXACT spelling of 'ListGuru') and in > the message BODY, include a line containing: UNSUB ORACLE-L > (or the name of mailing list you want to be removed from). You may > also send the HELP command for other information (like subscribing). > > > > -- > Please see the official ORACLE-L FAQ: http://www.orafaq.net > -- > Author: Stefan Jahnke > INET: [EMAIL PROTECTED] > > Fat City Network Services -- 858-538-5051 http://www.fatcity.com > San Diego, California -- Mailing list and web hosting services > --------------------------------------------------------------------- > To REMOVE yourself from this mailing list, send an E-Mail message > to: [EMAIL PROTECTED] (note EXACT spelling of 'ListGuru') and in > the message BODY, include a line containing: UNSUB ORACLE-L > (or the name of mailing list you want to be removed from). You may > also send the HELP command for other information (like subscribing). __________________________________ Do you Yahoo!? Protect your identity with Yahoo! Mail AddressGuard http://antispam.yahoo.com/whatsnewfree -- Please see the official ORACLE-L FAQ: http://www.orafaq.net -- Author: Rachel Carmichael INET: [EMAIL PROTECTED] Fat City Network Services -- 858-538-5051 http://www.fatcity.com San Diego, California -- Mailing list and web hosting services --------------------------------------------------------------------- To REMOVE yourself from this mailing list, send an E-Mail message to: [EMAIL PROTECTED] (note EXACT spelling of 'ListGuru') and in the message BODY, include a line containing: UNSUB ORACLE-L (or the name of mailing list you want to be removed from). You may also send the HELP command for other information (like subscribing).
