Rollback? > -----Original Message----- > From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On > Behalf Of Cary Millsap > Sent: 05 November 2003 20:39 > To: Multiple recipients of list ORACLE-L > Subject: RE: RE: How do you generate primary keys? > > > I've heard of people using instance startup triggers to > insert VOID records in cases where there are gaps. I haven't > thought about it much recently, but I can't presently think > of occasions when gaps occur other than instance shutdown. > > > Cary Millsap > Hotsos Enterprises, Ltd. > http://www.hotsos.com > > Upcoming events: > - Performance Diagnosis 101: 11/19 Sydney > - SQL Optimization 101: 12/8-12 Dallas > - Hotsos Symposium 2004: March 7-10 Dallas > - Visit www.hotsos.com for schedule details... > > > -----Original Message----- > Jamadagni, Rajendra > Sent: Wednesday, November 05, 2003 12:14 PM > To: Multiple recipients of list ORACLE-L > > Ryan, > > hypothetically, When you have a requirement that no gaps > allowed in a sequence no matter what, would you still use sequences? > > Raj > -------------------------------------------------------------- > ---------- > -------- > Rajendra dot Jamadagni at nospamespn dot com > All Views expressed in this email are strictly personal. > QOTD: Any clod can have facts, having an opinion is an art ! > > > -----Original Message----- > Sent: Wednesday, November 05, 2003 12:09 PM > To: Multiple recipients of list ORACLE-L > > > do people actually use a table as a counter these days? Now > Im 'assuming' they are jsut people who dont know about > sequences or are there actually 'professionals' who know > about sequencse and decide not to use them. > > id assume those tables were used in oracle 5 days because > either sequences didnt exist or they werent designed well? > > > > From: "Cary Millsap" <[EMAIL PROTECTED]> > > Date: 2003/11/05 Wed AM 11:04:25 EST > > To: Multiple recipients of list ORACLE-L <[EMAIL PROTECTED]> > > Subject: RE: How do you genrate primary keys? > > > > "Hit a table that keeps a counter" will not scale (will not > perform at > > high concurrency). It will cause you no end of "buffer busy waits" > > waits, "latch free" waits for a cache buffers chains latch (even if > > db_block_buffers, _db_block_hash_buckets, and > _db_block_hash_latches > > could be set to infinity), lots of unnecessary CPU service > consumption > > due to the spinning (especially if you try to tinker with > _spin_count), > > and possibly a wide range of side effects including "write complete > > waits" waits and others. > > > > > > Cary Millsap > > Hotsos Enterprises, Ltd. > > http://www.hotsos.com > > > > Upcoming events: > > - Performance Diagnosis 101: 11/19 Sydney > > - SQL Optimization 101: 12/8-12 Dallas > > - Hotsos Symposium 2004: March 7-10 Dallas > > - Visit www.hotsos.com for schedule details... > > > > > > -----Original Message----- > > Hemant K Chitale > > Sent: Wednesday, November 05, 2003 8:25 AM > > To: Multiple recipients of list ORACLE-L > > > > > > My comments [probably off-the-cuff without spending much > time thinking > > the issues through .....?] > > > > 1. Hit a table that keeps a counter. > > Used to be a mechanism in the Oracle5 days [If I remember > correctly, > > Sequences came in Oracle6]. Issues were with locking the single > > record used as the generator or scanning for the max(value) of the > > key. Not quite sure I understand how you encountered concurrency > > issues, though. > > > > > > 2. Stored sequences. > > Although I prefer not to use a Sequence as a PK in itself > [preferring > > natural column/s which are Unique keys, with the NOT NULL, > of course], > > I have used a Sequence in an Advanced Replication > implementation that > > had no Primary Key and I needed a PK for Conflict > Resolution [this was > > years ago and, if you ask me, I can't remember all the details] > > > > 3. SYS_GUID > > SYS_GUID I've never used. It doesn't generate a NUMBER > value so it is > > not really similar to a Sequence. Can user's key in a > > SYS_GUID-generated value ? Is it really "human readable" or > > "recallable" as a plain NUMBER, Security Security Number, > > ZIP Code ?? > > > > 4. Similar to SYS_GUID .. > > You hit on a fortuitous combination of columns. > > > > > > Hemant > > > > At 05:19 AM 05-11-03 -0800, you 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). > > > > Hemant K Chitale > > Oracle 9i Database Administrator Certified Professional > > My personal web site is : http://hkchital.tripod.com > > > > > > -- > > Please see the official ORACLE-L FAQ: http://www.orafaq.net > > -- > > Author: Hemant K Chitale > > 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: Cary Millsap > > 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: <[EMAIL PROTECTED] > 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). > > ************************************************************** > ********** > ************** > This e-mail message is confidential, intended only for the named > recipient(s) above and may contain information that is > privileged, attorney work product or exempt from disclosure > under applicable law. If you have received this message in > error, or are not the named recipient(s), please immediately > notify corporate MIS at (860) 766-2000 and delete this e-mail > message from your computer, Thank you. > ************************************************************** > ********** > **************4 > -- > Please see the official ORACLE-L FAQ: http://www.orafaq.net > -- > Author: Jamadagni, Rajendra > 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: Cary Millsap > 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). >
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