Thread: Re: [PATCHES] Summary table trigger example race condition
On Fri, Jan 06, 2006 at 02:00:34PM +1300, Mark Kirkwood wrote: > However, I think the actual change is not quite right - after running DOH! It would be good if doc/src had a better mechanism for handling code; one that would allow for writing the code natively (so you don't have to worry about translating < into < and > into >) and for unit testing the different pieces of code. Anyway, updated patch attached. -- Jim C. Nasby, Sr. Engineering Consultant jnasby@pervasive.com Pervasive Software http://pervasive.com work: 512-231-6117 vcard: http://jim.nasby.net/pervasive.vcf cell: 512-569-9461
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On Sun, Jan 08, 2006 at 04:13:01PM +1300, Mark Kirkwood wrote: > After re-examining the original code, it looks like it was not actually > vulnerable to a race condition! (it does the UPDATE, then if not found > will do an INSERT, and handle unique violation with a repeat of the same > UPDATE - i.e three DML statements, which are enough to handle the race > in this case). What happens if someone deletes the row between the failed insert and the second update? :) AFAICT, example 36-1 is the only way to handle this without creating a race condition. > However Jim's change handles the race needing only two DML statements in > a loop, which seems much more elegant! In addition it provides a nice > example of the 'merge' style code shown in e.g 36-1. What's SOP here... should I ping someone to let them know this patch should be committed now that those who care are happy with it? -- Jim C. Nasby, Sr. Engineering Consultant jnasby@pervasive.com Pervasive Software http://pervasive.com work: 512-231-6117 vcard: http://jim.nasby.net/pervasive.vcf cell: 512-569-9461
Mark Kirkwood wrote: > Yes it would - I usually build the SGML -> HTML, then cut the code out > of a browser session to test - the pain is waiting for the docs to build. FWIW, what I do is to build a cut-down version of postgres.sgml to include only the file you want to check. I think there is a suggestion somewhere telling you to add a DTD line to compile only that file.
Jim C. Nasby wrote: > DOH! It would be good if doc/src had a better mechanism for handling > code; one that would allow for writing the code natively (so you > don't have to worry about translating < into < and > into >) > and for unit testing the different pieces of code. <![CDATA[ weird stuff ]]> -- Peter Eisentraut http://developer.postgresql.org/~petere/
On Thu, Jan 12, 2006 at 09:58:54PM +0100, Peter Eisentraut wrote: > Jim C. Nasby wrote: > > DOH! It would be good if doc/src had a better mechanism for handling > > code; one that would allow for writing the code natively (so you > > don't have to worry about translating < into < and > into >) > > and for unit testing the different pieces of code. > > <![CDATA[ > > weird stuff > > ]]> While that certainly takes care of < and >, it doesn't do anything for allowing testing of code examples. If instead we put code snippets into seperate files that could actually be run via psql, we could actually test the code examples that we're including in the docs. We could also easily capture the output from that code to include in the docs. If things go well, I'll soon be working on a database book, and my plan is to use this technique to (hopefully) speed up production. If that happens I'll post the code here for folks to look at. -- Jim C. Nasby, Sr. Engineering Consultant jnasby@pervasive.com Pervasive Software http://pervasive.com work: 512-231-6117 vcard: http://jim.nasby.net/pervasive.vcf cell: 512-569-9461
Patch applied to HEAD and 8.1.X. Thanks. --------------------------------------------------------------------------- Jim C. Nasby wrote: > On Fri, Jan 06, 2006 at 02:00:34PM +1300, Mark Kirkwood wrote: > > However, I think the actual change is not quite right - after running > > DOH! It would be good if doc/src had a better mechanism for handling > code; one that would allow for writing the code natively (so you don't > have to worry about translating < into < and > into >) and for > unit testing the different pieces of code. > > Anyway, updated patch attached. > -- > Jim C. Nasby, Sr. Engineering Consultant jnasby@pervasive.com > Pervasive Software http://pervasive.com work: 512-231-6117 > vcard: http://jim.nasby.net/pervasive.vcf cell: 512-569-9461 [ Attachment, skipping... ] > > ---------------------------(end of broadcast)--------------------------- > TIP 6: explain analyze is your friend -- Bruce Momjian | http://candle.pha.pa.us pgman@candle.pha.pa.us | (610) 359-1001 + If your life is a hard drive, | 13 Roberts Road + Christ can be your backup. | Newtown Square, Pennsylvania 19073
On Fri, Jan 06, 2006 at 04:46:26PM +1300, Mark Kirkwood wrote: > Jim C. Nasby wrote: > >On Fri, Jan 06, 2006 at 02:00:34PM +1300, Mark Kirkwood wrote: > > > >>However, I think the actual change is not quite right - after running > > > > > >DOH! It would be good if doc/src had a better mechanism for handling > >code; one that would allow for writing the code natively (so you don't > >have to worry about translating < into < and > into >) and for > >unit testing the different pieces of code. > > > > Yes it would - I usually build the SGML -> HTML, then cut the code out > of a browser session to test - the pain is waiting for the docs to build. Ok, here's some *Uber Ugly* code I hacked together to do something similar for a potential book project. It's based loosely on docbook. -- Jim C. Nasby, Sr. Engineering Consultant jnasby@pervasive.com Pervasive Software http://pervasive.com work: 512-231-6117 vcard: http://jim.nasby.net/pervasive.vcf cell: 512-569-9461
On Wed, Feb 22, 2006 at 06:50:32PM -0600, Jim C. Nasby wrote: > Ok, here's some *Uber Ugly* code I hacked together to do something > similar for a potential book project. It's based loosely on docbook. Ok, no, for real this time... it's at http://jim.nasby.net/sgmlcode/ Thanks to all that pointed it out... -- Jim C. Nasby, Database Architect decibel@decibel.org Give your computer some brain candy! www.distributed.net Team #1828 Windows: "Where do you want to go today?" Linux: "Where do you want to go tomorrow?" FreeBSD: "Are you guys coming, or what?"