Oracle

Postgres vs. Oracle access paths VI – Index Scan

By Franck Pachot . In the previous post my queries were still reading the indexed column only, from a table which had no modifications since the last vacuum, and then didn't need to read table pages:(…)

Postgres vs. Oracle access paths IV – Order By and Index

By Franck Pachot . I realize that I'm talking about indexes in Oracle and Postgres, and didn't mention yet the best website you can find about indexes, with concepts and examples for all RDBMS: http://use-the-index-luke.com. You(…)

Exadata Capacity on Demand and Elastic Rack

By Franck Pachot . Since X4 we can do Capacity on Demand on Exadata: disable some CPU cores to lower cost of Oracle Database licenses. Depending on the models, and the configuration, there are different minimums and here is a(…)

Postgres vs. Oracle access paths III – Partial Index

By Franck Pachot . In the previous post I said that an Index Only Access needs to find all rows in the index. Here is a case where, with similar data, Postgres can find all rows(…)

Postgres vs. Oracle access paths II – Index Only Scan

By Franck Pachot . In the previous post I've explained a sequential scan by accident: my query needed only one column which was indexed, and I expected to read the index rather than the table. And(…)

Oracle Cloud: script to stop all PaaS services

By Franck Pachot . With metered cloud services, keeping all your instances running may become expensive. The goal is to start them only when you need them. Here is a script that stops all instances you have on the Oracle(…)

Display Data Guard configuration in SQL Developer

By Franck Pachot . The latest version of SQL Developer, the 17.2 one released after Q2 of 2017, has a new item in the DBA view showing the Data Guard configuration. This is the occasion to show how you can(…)

Postgres vs. Oracle access paths I – Seq Scan

By Franck Pachot . Here is the first test I've done for my Postgres vs. Oracle access paths series and the first query did a sequential scan. It illustrates the first constant you find in the(…)

Postgres vs. Oracle access paths – intro

By Franck Pachot . This is the start of a series on PostgreSQL execution plans, access path, join methods, hints and execution statistics. The approach will compare Postgres and Oracle. It is not a comparison to see which one is(…)

Postgres vs. Oracle access paths VII – Bitmap Index Scan

By Franck Pachot . In the previous post we have seen the Index Scan, where a where clause condition uses the index structure to find rows and then fetches remaining columns from the table. The case(…)