Comments on: Ancient History

By: Fragmentation 2 « Oracle Scratchpad

Fragmentation 2 « Oracle Scratchpad — Fri, 16 Jul 2010 18:52:41 +0000

[...] Reading: a little bit of ancient history that I published long before Oracle introduced locally managed tablespace wtith uniform extent [...]

By: Tablespaces « Oracle Scratchpad

Tablespaces « Oracle Scratchpad — Fri, 19 Jun 2009 19:09:59 +0000

[...] Troubleshooting — Jonathan Lewis @ 7:08 pm UTC Jun 19,2009 This could nearly be one for the “ancient history” series, because it starts with a quote from that marvellous book “Practical Oracle 8i”, [...]

By: Ancient History 2 « Oracle Scratchpad

Ancient History 2 « Oracle Scratchpad — Sun, 31 May 2009 19:11:04 +0000

[...] under: Uncategorized — Jonathan Lewis @ 7:09 pm UTC May 31,2009 Some time ago I posted an extract from a short presentation I had given at the UKOUG annual conference about 12 years [...]

By: Polarski Bernard

Polarski Bernard — Thu, 03 Jul 2008 07:41:54 +0000

Humm… is that enough material to demonstrate correlation between “Buffer hit ratio” and “tablespace fragmentations”?

By: Connor

Connor — Wed, 02 Jul 2008 14:44:57 +0000

Can’t remember the precise date, but Dave Ensor came out to Oz in the mid 90′s and did a similar talk – something like ’20 stupid things people do’….As I ticked off around 17 of the 20 as things I was regularly doing, I decided it might be time to learn a little more :-)

By: Jonathan Lewis

Jonathan Lewis — Wed, 02 Jul 2008 10:26:42 +0000

Joel,
The presentation was 45 minutes, and apart from the introduction, background and conclusion there are only seven slides. That makes the slides very sparse talking points – so I’m not keen to post the presentation as someone’s bound to misinterpret it. (How long do you think it’s going to be before someone cites the title from this slide without reading the rest of the note ?)

The comments I chose to discuss were:

1) Objects should be compressed to one extent
2) Fragmented tablespaces are bad
3) Raw disks improve performance
4) Raw disk is hard to handle
5) Tablescans are bad
6) Foreign keys need to be indexed
7) Every site needs a full-time DBA

In outline, omitting a few of the details and caveats, the comments that went with them were along the lines of:

1) Waste of time (unless you were still running 5.1)

2) Doesn’t happen if you set things up properly

3) Maybe/Maybe not – depending on the quality your application design and code. (The discussions would probably be about direct I/O – in it’s various forms – now).

4) Not with logical volume managers (which had been around for a few years by then). (I don’t think anyone would bother to make this remark nowadays).

5) Not necessarily (This still has to be explained fairly frequently !)

6) Not necessarily (This still has to be explained fairly frequently !)

7) Times and working environments change, but the point I was making with this one was that if a DBA doesn’t have to spend all their time dealing with design and coding errors, they can keep an eye on quite a lot of databases. At the time I was suggesting a couple of hours per week. (Funnily enough, the notes that go with that slide say that one of the things a DBA may have to do is an occasional index rebuild).

The closing slide was a bit of a classic, it said:

“If it’s going to make a big difference, don’t believe it until you’ve proved it.”

If I were to present that last slide today, I’d probably change it to “If it’s supposed to make a big difference …”.

By: joel garry

joel garry — Tue, 01 Jul 2008 22:13:55 +0000

This is great! Can you post the whole thing? Are there any you would disagree with now? Were you making assumptions about different sized data or volatility per tablespace?