Tag: performance

What are Statistics? There are multiple paths a database can use to answer a query, some of them being faster and more efficient than others. It is the job of the query optimizer to evaluate and choose the best path,…

AWR report is a great source of aggregated information on top activities happening in our databases. I use data collected in AWR quite often, and obviously the easiest way of getting the data out from the AWR is by running the…

The question of whether a database has enough redo logs available is quite common. The documentation suggests to use FAST_START_MTTR_TARGET and V$INSTANCE_RECOVERY.OPTIMAL_LOGFILE_SIZE to identify “the optimal” redo log size based on the target recovery time. I’ve never used it and…

When I first saw the suffix BATCHED in an Oracle execution plan from 12c, I was curious to see what is hidden behind and how it works. I had some spare time for testing and wanted to share my findings…

Sometimes it’s useful to check how performance of a SQL statement changes over time. The diagnostic pack features provide some really useful information to answer these questions. The data is there, but it not always easy to retrieve it, especially if…

The time to respond There was a question at Pythian a while ago on how to monitor Oracle database instance performance and alert if there is significant degradation. That got me thinking, while there are different approaches that different DBAs…

One of the biggest selling features of Oracle’s flagship engineered system – Exadata – is the storage offloading capabilities. Storage offloading allows data to be filtered as soon as it is read from storage, reducing the amount of data that…

I was recently playing with an Oracle XE database. The main benefit of Oracle XE is that it can be used free of charge.

This is a short blog post on how one can prove that a particular partition of the table or index is accessed by a specific query.

A little while ago I blogged about (and open sourced) an Impala-powered soccer visualization demo, designed to demonstrate just how responsive Impala queries can be. Since not everyone has the time or resources to run the project themselves, we’ve decided to host it ourselves on an EC2 instance.