Hotsos Symposium Speaker – Amit Poddar

Amit Poddar is a returning Hotsos Symposium presenter.


Amit PoddarAmit has been an Oracle Applications DBA since 1998. During this time, he has worked on many large Oracle Applications databases. Query tuning and Oracle Cost-Based Optimizer have always been his deepest interests. Tuning queries in Oracle Applications with often no access to the SQL itself has forced him to explore the mechanics of Oracle's cost-based optimizer and statistics gathering. Mr. Poddar has spoken about Oracle performance and other topics at OAUG, Hotsos Symposium 2009, and local Oracle User Groups.

Presentation Title

Evolution of Histograms in Oracle


For more than two decades, histograms have been used by query optimizers to produce efficient execution plans in cases of data skew. If and when to create a histogram on a column has been based on trial and error. Unfortunately, histograms are expensive to create, and may create more problems then they solve.

This presentation takes a single query, explores and explains the effects of different types and configuration of histograms on the execution plan. During this process, Amihay will explain histograms from a statistical perspective, which will help the audience develop an understanding of how to analyze the data distribution as well as when and how to create histograms based on the principals of statistics instead of rules of thumb.

The presentation covers equi-width, equi-depth, frequency, top-n frequency and hybrid (compressed) histograms. We will also go into internal details of Oracle's histogram collection and implementation including the enhancements introduced in 12c.

Presentation Materials

Presentation materials are available online to attendees only. Amit's materials may be found at the Hotsos portal. Attendees may use their portal ids to log in.


The speaker schedules can be found at the following links: