Tag: Technical Blog

Interesting variations in outcome when cloning a CDB with a subset of PDBs in Oracle

Recently I was working on a client request where a CDB along with a subset of its PDBs had to be cloned to a new server for testing purposes. This post illustrates that in certain circumstances the outcome of this…

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After logon trigger in user schema and FRA full situation hang the database

This blog post is about a scenario where a combination of a logon trigger performing DML operations at user login time (writing to a custom audit table), and a Fast recovery area (FRA) full situation brings the database to a…

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Database Upgrade Fails With “unexpected error in validate_credentials”

unexpected error

This is a blog post about an issue that can occur during a database upgrade and produces a misleading error message. If you’re already aware of it, the workaround is trivial. However, when it happened to me during the testing…

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Statspack vs. AWR: Wrong number of SQL Executions


This post is about a Statspack anomaly I discovered while analyzing execution trends of a particular SQL on one of our clients’ databases. I decided to share it, since its appearance can be misleading. The database in question was an…

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Part Four: Deploying High Availability Applications in Oracle Cloud Infrastructure—Oracle Enterprise Manager 13.5 Setup


This is the fourth in a series of blog posts that covers the details to deploy a high available set up of Oracle Enterprise Manager 13.5 using Oracle Cloud Infrastructure’s resources.   Recap This is the fourth of a six-part…

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Python: Using Dataclasses to Model Your Data

3d chart data model tablet

Here at Pythian, we love our data. Our code is no exception (pun sort of intended), so I’ll be covering dataclasses in Python today. The problem As a Python developer, you’ve almost certainly run into code that looks like the…

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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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