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PostgreSQL Internals

Optimizer index caching in PostgreSQL

Optimizer index caching in PostgreSQL is the process by which the database caches the index pages in memory to speed up the execution of queries. This feature helps improve the performance of queries by reducing […]

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MySQL Performance

When MySQL ignores histograms?

MySQL can ignore histograms in the query optimizer when it determines that using the histograms would not provide any benefit to the query execution plan. This can occur in several cases, including: Why MySQL ignores […]

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MySQL Troubleshooting

Troubleshooting Mutex Contention in MySQL

Mutex contention occurs in MySQL when multiple threads attempt to access a shared resource, such as a data structure or a system resource, simultaneously. Because only one thread can access the resource at a time, […]

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MySQL Internals

How is MVCC implemented in InnoDB?

Multiversion Concurrency Control (MVCC) is a mechanism that is used by InnoDB, the default storage engine in MySQL, to provide transactional consistency and support for concurrent access to the same data. In InnoDB, MVCC is […]