MinervaDB Blog: Mastering WebScale Database Infrastructure

MySQL Streaming Versus Blocking Operators Explained

In MySQL, operators in a query execution plan can be classified as streaming or blocking. This classification is based on how they process and propagate rows during query execution. Let’s explore the differences between streaming […]

InnoDB Redo Performance: Troubleshooting Tips and Tricks

Troubleshooting redo performance in InnoDB involves identifying and addressing potential bottlenecks or issues that affect the efficiency of redo log processing. The redo log plays a critical role in ensuring data durability and crash recovery […]

MySQL Scalar Subquery Unnesting transformation

Scalar subquery unnesting is a transformation technique that the MySQL optimizer uses to optimize queries involving scalar subqueries. Scalar subqueries return a single value. You typically use them in expressions or as part of the […]

How to control MySQL execution plans with hints?

In MySQL, you can use query hints to give suggestions or directives to the query optimizer. These hints guide the optimizer on how to generate the execution plan for a specific query. As a result, […]

PostgreSQL Statistics: How to Gather Them Only When Stale

In PostgreSQL, you can gather statistics only when they become stale by using the pg_stat_statements extension along with the track_activity_query_size configuration parameter. Follow these steps to achieve this: CREATE EXTENSION pg_stat_statements; 3. Query the pg_stat_statements […]

PostgreSQL SQL Plans: Why They Change for the Worse

In PostgreSQL, several reasons can cause SQL statement plans to worsen over time. These changes may lead to decreased query performance and unexpected behavior. Below are some common factors that contribute to deteriorating SQL statement […]

PostgreSQL Concurrent Statistics: How to Implement Concurrent Gathering

Concurrent statistics gathering in PostgreSQL allows the system to collect table and column statistics without blocking concurrent read and write operations. As a result, this feature ensures accurate and up-to-date statistics while minimizing the impact […]

PostgreSQL Bind-Aware Cursor Sharing: How to Force It in a Query

In PostgreSQL, you can force a query to use bind-aware cursor sharing by utilizing the CURSOR_SHARING parameter. By setting CURSOR_SHARING to ‘FORCE’, PostgreSQL will attempt to share cursors for similar queries with different literal values. […]

PostgreSQL Query Optimizer: Troubleshooting Unconsidered Hints

PostgreSQL’s query optimizer (or planner) creates optimal execution plans for SQL queries by evaluating multiple possible plans and selecting the fastest one. [^1] Understanding PostgreSQL’s Approach to Optimizer Hints PostgreSQL takes a deliberately cautious approach […]

How to have PostgreSQL execution plan with run-time?

PostgreSQL execution plan with run-time In PostgreSQL, you can obtain the execution plan with runtime information using the EXPLAIN (ANALYZE, VERBOSE) command. This command in particular, provides a detailed execution plan along with actual runtime […]