Insight for DBAs

MongoDB 4.4 Performance Regression: Overwhelmed by Memory

MongoDB 4.4 Performance Regression

There is a special collection of database bugs when the system starts to perform worse when given more resources. Examples of such bugs for MySQL I have:
Bug #15815 – This is where InnoDB on an 8-CPU system performed worse than on a 4-CPU system with increased concurrency.
Bug #29847 – This is a similar bug […]

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Percona Server for MongoDB 4.2 vs 4.4 in Python TPCC Benchmark

Percona Server for MongoDB 4.2 vs. 4.4

Following my previous blogs on py-tpcc benchmark for MongoDB, Evaluating the Python TPCC MongoDB Benchmark and Evaluating MongoDB Under Python TPCC 1000W Workload, and the recent release of Percona Server for MongoDB 4.4, I wanted to evaluate 4.2 vs 4.4 in similar scenarios.
Hardware Specs
For the client and server, I will use identical bare metal servers, connected via […]

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How To Inject an Empty XA Transaction in MySQL

Inject an Empty XA Transaction in MySQL

If you are using XA transactions, then you’ve likely run into a few replication issues with the 2PCs (2 Phase Commits). Here is a common error we see in Percona’s Managed Services and a few ways to handle it, including injecting an empty XA transaction.

Shell

Last_Error: Error ‘XAER_NOTA: Unknown XID’ on query. Default database: ‘punisher’. Query: […]

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Data Consistency for RDS for MySQL: The 8.0 Version

data consistency rds mysql 8

In a previous blog post on Data Consistency for RDS for MySQL, we presented a workaround to manage run pt-table-checksum on RDS instances. However, if your instance is running a MySQL 8.0.X version, there’s a simpler way to check data consistency.
Starting with 8.0.1, MySQL introduced something called “Dynamic Privileges” which is a solution to grant […]

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How Much Memory Does the Process Really Take on Linux?

Memory Process takes on Linux

One of the questions you often will be faced with operating a Linux-based system is managing memory budget. If a program uses more memory than available you may get swapping to happen, oftentimes with a terrible performance impact, or have Out of Memory (OOM) Killer activated, killing process altogether.
Before adjusting memory usage, either by […]

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