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MinervaDB

MySQL Scalar Subquery Unnesting transformation

Scalar subquery unnesting is a transformation technique used by the MySQL optimizer to optimize queries that involve scalar subqueries. Scalar subqueries are subqueries that return a single value, typically used in expressions or as part […]

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MinervaDB

How invisible indexes in MySQL 8 works?

In MySQL 8, invisible indexes are a feature that allows you to create an index without it being used by the optimizer. This can be useful in situations where you want to test the impact […]

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MinervaDB

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 […]