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November 2009

Detect chained and migrated rows in Oracle – Part 1

I received a question about migrated rows recently.

It was about how to detect migrated rows in a 200TB data warehouse, with huge tables – as the ANALYZE TABLE xyz LIST CHAINED ROWS INTO command can not be automatically parallelized at table level (as DBMS_STATS can be, but oh, DBMS_STATS doesn’t gather the migrated/chained row info). Therefore the analyze command would pretty much run forever before returning (and committing) the chained row info in the output table. Also as there are regular maintenance jobs running on these tables (I suspect partition maintentance for example), then it wouldn’t be nice to keep running ANALYZE on the whole table constantly.

So, is there any faster or better way for finding the amount of migrated rows?

Ihave two answers to this.

Answer 1:

RHEV (Red Hat Enterprise Virtualization) is out!!! :)

The company I work for, SQL*Wizard,  is a RedHat Advanced Business Partner so I was lucky to get my hands dirty on the BETA release of RHEV, also a pleasure to work with Siva Shunmugam (Sr. Solutions Architect@RedHat & RHCA). I must say, KVM is so fast… plus the RHEV manager is so cool as a management platform </p />
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11gR2: materialized view logs changes

In this post we are going to discuss some 11gR2 changes to materialized view logs that are aimed at increasing the performance of the fast-refresh engine of materialized views (MVs), especially the on-commit variant.
The MV logs, in 10gr2, now comes in two flavours: the traditional (and still the default) timestamp-based one and the brand [...]

Listing files with the external table preprocessor in 11g

Using the 11g external table preprocessor to get directory listings in SQL. October 2009