Author Archives: idatcu

Oracle Bitmap Index

Common usage of Bitmap Indexes is a data warehousing environment. This implies large amounts of data, high level of ad-hoc queries but a low level of concurrent DLM transactions. Why to use? reduced response time reduced storage requirements compared to other … Continue reading

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Buffer Busy Waits – Reverse Key Index – Demo

We discussed earlier about indexing, and specifically reverse key indexing. I mentioned that is a solution for buffer busy waits on numerical consecutive inserted keys (like the sequence based generated ones) . This post will test that solution. For regular … Continue reading

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Oracle Reverse Index

This is one of the least used Oracle indexes I’ve encountered in a data-warehousing environment. However, a very good instrument in performance problems on OLTPs. To understand a reverse key index, we must first look at the regular b-tree index … Continue reading

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Cursor Loop Updates

I’m writing this topic mostly for database developer coming from the programming world. I have seen various procedural units which use the for syntax to run updates on base tables. Scenarios like the one bellow. FOR update SQL: for i … Continue reading

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Oracle: Partitioning and Indexes 

As I’ve been presenting in the last couple of posts on partitioning, one of the major benefits of this database option is basically the selectivity when filtering on the partition key, what we currently call partition pruning. Now, what we’ve … Continue reading

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Oracle: Partition by List Sub-Partition by Range– Example

The following post will walk you trough an exercise of creating a partitioned table, using the list partitioning, with range sub-partitioning (explicit definition of partitions and sub-partitions naming), populating and testing the partition pruning. Please note I will also post … Continue reading

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Working with Large Data Volumes – Partitioning

As more and more the increase in information is getting visible to each database user, there comes a question on how are we to process these volumes in a Data Warehouse environment. One of the first answers provided by Oracle … Continue reading

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