Comments for Oracloid Blog

Comment on HASH GROUP BY can give wrong result in Oracle 10.2 by Alex Gorbachev

Alex Gorbachev — Fri, 12 Sep 2008 03:19:12 +0000

Yeah… good examples of the cases when involving someone who have already done it *many* times pays off.

Comment on HASH GROUP BY can give wrong result in Oracle 10.2 by Sudhir Kaul

Sudhir Kaul — Fri, 12 Sep 2008 02:44:10 +0000

I encountered the same bug in my project when migrating from 9i to 10g.
After a lot of efforts I could make out that this is a bug in Oracle.

Comment on HASH GROUP BY can give wrong result in Oracle 10.2 by Saurabh Dhawan

Saurabh Dhawan — Thu, 11 Sep 2008 09:33:57 +0000

Gosh… I have this exact bug in my production environment… Spent two sleepless nights on debugging this issue..

Comment on My RSS Reader is Empty! by Alex Gorbachev’s RSS Feeds Aggregated at Oracloid Blog

Alex Gorbachev’s RSS Feeds Aggregated at Oracloid Blog — Thu, 31 Jul 2008 03:59:40 +0000

[...] Recent Comments Alex Gorbachev’s RSS Feeds Aggregated at Oracloid Blog on Moving to Canada… Oracle 10g RAC + Solaris 10g + VMwareAlex Gorbachev’s RSS Feeds Aggregated on Moving to Canada… Oracle 10g RAC + Solaris 10g + VMwareAppunti sul funzionamento di CBO in Oracle - Parte II « Oracle and other on Bind Variable Peeking with no HistogramsAlex Gorbachev on My RSS Reader is Empty!Michael O’Neill on My RSS Reader is Empty! [...]

Comment on Moving to Canada… Oracle 10g RAC + Solaris 10g + VMware by Alex Gorbachev’s RSS Feeds Aggregated

Alex Gorbachev’s RSS Feeds Aggregated — Tue, 29 Jul 2008 14:18:50 +0000

[...] platform and one month later moved it to my own website using Wordpress. Couple month later, I joined Pythian and, since then, the vast majority of my blogging activities has been on the Pythian Group [...]

Comment on Bind Variable Peeking with no Histograms by Appunti sul funzionamento di CBO in Oracle - Parte II « Oracle and other

Appunti sul funzionamento di CBO in Oracle - Parte II « Oracle and other — Tue, 15 Jul 2008 14:56:04 +0000

[...] NON SONO LE CATTIVE PRESTAZIONI O LE SCELTE SBAGLIATE DI CBO. Come dice bene Alex Gorbachev in un commento al suo post intitolato “Bind peeking with no histograms” l’unico e vero problema [...]

Comment on My RSS Reader is Empty! by Alex Gorbachev

Alex Gorbachev — Sun, 13 Jul 2008 17:37:51 +0000

Thanks Michael.
I have recently syndicated my posts from my company blog at pythian.com/blogs. I didn’t want to flood my subscribers with 100 posts so I decided to temporary break the feed.

However, from now on the feed from oracloid.com will contain all my posts regardless where they are posted. In the feed there will be a direct link to the original and there won’t be any additional clicks or so. I just wanted an easier way to give people the ability to subscribe only on my personal posts on the Pythian Group blog. It was possible before but wasn’t obvious for many.

Again, thanks for reading and letting me know!

Comment on My RSS Reader is Empty! by Michael O'Neill

Michael O'Neill — Sun, 13 Jul 2008 17:26:43 +0000

I was going through my Google Reader and cleaning out feeds I no longer read. The weird thing about your blog’s feed is that this is the most recent one in the feed. All subsequent posts are not getting published in a manner Google Reader understands.

Just thought I’d let you know.

Comment on HASH GROUP BY can give wrong result in Oracle 10.2 by Alex Fatkulin

Alex Fatkulin — Fri, 13 Jun 2008 17:59:40 +0000

Dinesh,

10GR2 added a new group by algorithm — hash group by, that’s why you have your observation.

That being said, group by was never documented to return rows in a sorted order in any version of Oracle, try execute it in parallel for example (that’s it — altering the default degree for a table will make your code which relies on a group by doing a sort to break because your code was based on a wrong assumption).

Comment on HASH GROUP BY can give wrong result in Oracle 10.2 by Dinesh Chandar

Dinesh Chandar — Fri, 13 Jun 2008 17:05:14 +0000

When ever you give a group by in Oracle, as far as I remember Oracle used to do a aggregated Sort operation.

I am not sure why it was stopped all of a sudden.

A group by and then a sort by on the “same columns” was not a sensible way of doing it.