Automatic Segment Space -v- Freelist Management for PeopleSoft Temporary Records
.nobr br { display: none }Earlier this year, I wrote about some research into the effects of concurrent TRUNCATE TABLE operations in concurrent PeopleSoft Application Engine process. Since then I have...
View ArticleAutomatic Segment Space -v- Freelist Management for PeopleSoft Temporary Records
.nobr br { display: none }Earlier this year, I wrote about some research into the effects of concurrent TRUNCATE TABLE operations in concurrent PeopleSoft Application Engine process. Since then I have...
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Quiz Night
I've recently come across an interesting variation of a "famous" ASSM bug. Probably some of you will remember that ASSM bug that was caused by row migrations in larger block sizes (16K/32K). If you...
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ASSM ouch!
Here’s a nasty little surprise I got last week while investigating an oddity with stats collection. I wanted to create a table in an ASSM tablespace and populate it from two or three separate sessions...
View ArticleASSM bug reprise - part 1
This was meant to be published shortly after my latest quiz night post as an explanatory follow up, but unfortunately I only managed to complete this note by now.There is a more or less famous bug in...
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ASSM
Here’s an interesting little detail (obvious AFTER the event) about space management with ASSM (automatic segment space management). It starts with this question on OTN:When I alter table deallocate...
View ArticleASSM bug reprise - part 2
IntroductionIn the first part of this post I've explained some of the details and underlying reasons of bug 6918210. The most important part of the bug is that it can only be hit if many row migrations...
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Why Is My Index Not Being Used Solution (Eclipse)
Well done to everyone that got the correct answer Indeed, the subtle but significant difference between the two demos was that demo one created the table in a tablespace called USER_DATA with manual...
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Curious Case Of The Ever Increasing Index Solution (A Big Hurt)
Based on the excellent comments in the Quiz post, we have some clever cookies out there I guess the first thing to point out is that based in the basic scenario provided, the index shouldn’t ordinarily...
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Important !! Clustering Factor Calculation Improvement (Fix You)
Believe me, this article is worth reading I’m currently not allowed to discuss Oracle 12c Database goodies but I am allowed to discuss things perhaps initially intended for 12c that are currently...
View ArticleASSM
A couple of thoughts.The intent of ASSM is to minimise contention when multiple small transactions are busy inserting data concurrently into the same table. As a consequence, you may be able to find a...
View Articledbms_space usage
Just throwing out a brief comment (one of my many draft notes that I don’t have time to complete) about the dbms_space package. You’re probably familiar with this package and how, for ASSM segments, it...
View ArticleASSM Truncate.
Here’s one that started off with a tweet from Kevin Closson, heading towards a finish that shows some interesting effects when you truncate large objects that are using ASSM. To demonstrate the problem...
View ArticleLOB Space
Following on from a recent “check the space” posting, here’s another case of the code not reporting what you thought it would, prompted by a question on the OTN database forum about a huge space...
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Why A Brand New Index Might Benefit From An Immediate Coalesce (One Slip)
A recent question on the OTN Forums Reg: Index – Gathering Statistics vs. Rebuild got me thinking on a scenario not unlike the one raised in the question where a newly populated index might immediately...
View ArticleASSM argh!
Here’s a problem with ASSM that used to exist in older versions of Oracle had disappeared by 11.2.0.4 and then re-appeared in 12.1.0.2 – disappearing again by 12.2.0.1. It showed up on MoS a few days...
View ArticleASSM Argh 2
After yesterday’s post one of the obvious follow-up questions was whether the problem I demonstrated was a side effect of my use of PL/SQL arrays and loops to load data. What would happen with a pure...
View ArticleASSM tangle
Here’s a follow-on from Tuesday’s (serious) note about a bug in 12.1.0.2 that introduces random slowdown on large-scale inserts. This threat in this note, while truthful and potentially a nuisance, is...
View ArticleRedo Dumps
A thread started on the Oracle-L list-server a few days ago asking for help analysing a problem where a simple “insert values()” (that handled millions of rows per day) was running very slowly. There...
View ArticleOracle 19c Automatic Indexing: Common Index Creation Trap (Rat Trap)
When I go to a customer site to resolve performance issues, one of the most common issues I encounter is in relation to inefficient SQL. And one of the most common causes for inefficient SQL I...
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