Conditional uniqueness

A quick fly through the options for conditional uniqueness. Requirement #1: I want uniqueness on a column but only under certain conditions. For example, I have an active flag and I want to make sure there...
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By the Poolside: An Introduction to ADF BC Application Module Pooling

As the ADF Architecture TV series draws to a close with just a few episodes left to publish, Oracle's ADF product management team is still dedicated to creating external training to assist customers in...
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Getting the database parameters from a spfile

There’s been some debate about how to get the parameters from a spfile. A spfile is a binary version of the parameter file of the Oracle database. I added to the debate that my experience is that...
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Reconstructing oratab from the cluster registry

At the Accenture Enkitec Group we have a couple of Exadata racks for Proof of Concepts (PoC), Performance validation, research and experimenting. This means the databases on the racks appear and vanish...
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Delete Costs

One of the quirky little anomalies of the optimizer is that it’s not allowed to select rows from a table after doing an index fast full scan (index_ffs) even if it is obviously the most efficient...
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Room for Improvement – Using DBMS_REDEFINITION with Spatial Data

Resizing a Column in a Table With a Spatial Column Recently a client asked for help with using DBMS_REDEFINITION to modify a column in a table. As the intent was to reduce the precision of a numeric column,...
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Cluster Nulls

Yesterday’s posting was a reminder that bitmap indexes, unlike B-tree indexes in Oracle,  do store entries where every column in the index is null. The same is true for cluster indexes –...
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BGOUG Spring 2014 : Summary

I know I keep calling it the “spring” conference, but in my mind the two BGOUG conferences are always spring and autumn. This year the “spring” conference was a little late, hence...
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Execution Plans

This is the index to a series of articles I’ve been writing for redgate, published on their AllThingsOracle site, about generating and reading execution plans. I’ve completed a few articles...
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Bitmap Nulls

It’s fairly well known that in Oracle B-tree indexes on heap tables don’t hold entries where all the indexed columns are all null, but that bitmap indexes will hold such entries and execution...
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