Author Archives: idatcu

Oracle Indexing

Indexing is one of the most frequent approaches when resolving query performance issues raised within a database (though not necessary the right approach, but we can pick this up later). However, in order to better use indexing strategies, we should … Continue reading

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Oracle Index Organized Table(IOT)

What is an IOT? An IOT implies having your entire table indexed, within the same B-Tree structure. Should be used for larger scale tables or dimensions, highly used within the database. How to? Accessing the data is done via the … Continue reading

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Oracle Function Based Index

What is a Function-Based Index? A function-based index is an index created on the result of a function or expression. This type of index is more used for situations with atypical searches on the specified columns (e.g. search on an … Continue reading

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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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