MySQL / MariaDB: Waiting for table flush
Troubleshooting performance degradation caused by pileup of queries stuck in “Waiting for table flush” state in MySQL and MariaDB.
MySQL / MariaDB: Waiting for query cache lock
by Gordan BobicTroubleshooting performance degradation caused by pileup of queries stuck in “Waiting for query cache lock” state in MySQL and MariaDB.
MySQL – Fixing: Got fatal error 1236 from master when reading data from binary log: log event entry exceeded max_allowed_packet; Increase max_allowed_packet on master;
by Gordan BobicIf you spend all day every day looking after hundreds of MySQL servers, the chances are that you have encountered this problem. And the chances are that if your servers are configured properly (i.e. you have the same configuration the master and the slaves), the error is almost certainly spurious and doesn’t mean what it […]
MariaDB Performance Tuning and MySQL Performance Tuning
by Aaron StapleA summary of basics of MariaDB and MySQL performance tuning, along with a few more advanced hints and tips. Beyond these, further tuning becomes very workload specific.
MariaDB and MySQL DROP / TRUNCATE Lock / Stall Bug, Mitigations and Workarounds
by Gordan BobicWhen you DROP or TRUNCATE a table or partition in MySQL and you have a large buffer pool, you may noticed a complete server lock-up or stall of multiple seconds. Mitigation and Workarounds.
MariaDB / MySQL Performance Tuning and Optimization: How to Delete Faster on MySQL
by Jonathan LevinDELETE statements can have a disproportionately high impact on performance of a database server. Here we explore techniques for optimizing them.
MariaDB / MySQL Performance Tuning and Optimization: Data Types
by Gordan BobicData types matching between the table columns and queries is important – mismatch usually prevents the use of indexes.
MariaDB / MySQL Performance Tuning and Optimization: Sub-SELECTs are Evil
by Gordan BobicMost DBAs know that sub-selects are typically bad for performance, but this example we encountered in the wild illustrates very well just how bad for performance sub-selects can be.
MariaDB / MySQL Performance Tuning and Optimization: Best Practices for Writing High Performance SQL Queries
by Gordan BobicIn this article we discuss a list of best practices to help you write queries that perform well and avoid writing queries that end up being unoptimizable.
MariaDB / MySQL Performance Tuning and Optimization: Avoiding ORs in Queries
by Gordan BobicORs in SQL queries are bad for performance. Here we describe a technique for doing away with the ORs to improve performance while still retaining functional equivalence of the query.
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