Tag: Technical Blog

Mitigating the Problems Created by Tombstones

Got too many tombstones? This blog post will talk about how to deal with tombstones once you already have them. For more information about tombstones, check out this post: Examining the Lifecycle of Tombstones in Apache Cassandra. Verifying the presence…

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Consuming Tweets Using Apache Beam on Dataflow

Apache Beam is an SDK (software development kit) available for Java, Python, and Go that allows for a streamlined ETL programming experience for both batch and streaming jobs. It’s the SDK that GCP Dataflow jobs use and it comes with…

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DML by Unique Index Supposedly Affecting Many Rows

This blog post is based on a real customer case, and illustrates how v$sql reports execution statistics for certain DML types of operations (I purposely have not named which DML types … yet). These reports can be misleading when troubleshooting…

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Issues With Database Service Names Starting With Pluggable Database (PDB) Name

In this post I’ll describe a problem which occurs when creating and using a database service name which starts with the pluggable database’s (PDB) name, and has a dot (“.”) after it: “<pdb_name>.<optional_suffix>.” I noticed this issue when I was…

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Query Statspack’s “SQL ordered by” Sections Over a Time Period

In this post, I’ll present the statspack_top_sqls.sql script, which returns SQL performance statistics by mining the Statspack repository. In a previous blog post, I presented the statspack_load_trends.sql and the AWR_load_trends.sql scripts, which provide a high-level overview of workload dynamics on…

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Mining Statspack and AWR Repositories for Historical Trends

There are various ways that we can approach the analysis of a past database performance problem. The initial steps usually differ based on their scope. Is it limited to a certain SQL/process/task, or is it perceived as a database-wide slowdown?…

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Three Announcements from Oracle OpenWorld You Probably Didn’t Hear

The buzz from OpenWorld this year was the permanently free Oracle Cloud offering, the new Exadata X8M (reportedly capable of 12 million I/O per second!), Oracle Autonomous Cloud at Customer, and the new Blockchain table. Here are three interesting or…

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Creating dynamic tasks using Apache Airflow

What’s Airflow? Apache Airflow is an open source scheduler built on Python. It uses a topological sorting mechanism, called a DAG (Directed Acyclic Graph) to generate dynamic tasks for execution according to dependency, schedule, dependency task completion, data partition and/or…

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Orphaned disks in OVM and what to do with them

Some time ago I was doing a maintenance on an OVM and noticed that it had significant number of disks without mapping to any virtual machine (I need to mention that the OVM cluster was a home for more than…

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New ORAchk 12.1.0.2.6 beta

Gleb Otochkin, Principal Consultant and Certified Oracle Expert at Pythian, discusses Oracle’s recently released new beta 12.1.0.2.6 version for the Orachk utility, and why Oracle DBAs should be using it.

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