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 […]
In MySQL, you can use query hints to provide suggestions or directives to the query optimizer about how to generate the execution plan for a specific query. Query hints allow you to have more control […]
In PostgreSQL, you can gather statistics only when they are stale by utilizing the pg_stat_statements extension and the track_activity_query_size configuration parameter. Here’s how you can achieve this: CREATE EXTENSION pg_stat_statements; 3. Query the pg_stat_statements View: […]
In PostgreSQL, there are several reasons why SQL statement plans can change for the worse over time. These changes can result in decreased query performance and unexpected behavior. Here are some common factors that can […]
Concurrent statistics gathering in PostgreSQL allows for collecting table and column statistics without blocking concurrent read and write operations. This feature helps ensure accurate and up-to-date statistics while minimizing the impact on database performance. Here’s […]
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. […]
Introduction: The PostgreSQL query optimizer plays a critical role in generating efficient execution plans for SQL queries. However, there may be instances where hints provided to the optimizer are not considered, resulting in unexpected query […]
In PostgreSQL, you can obtain the execution plan with runtime information using the EXPLAIN (ANALYZE, VERBOSE) command. This command provides a detailed execution plan along with actual runtime information, including the number of rows processed, […]
Introduction: PostgreSQL’s query optimizer plays a crucial role in determining the most efficient execution plan for SQL queries. In this article, we delve into the concept of SQL plan directives and their role in optimizing […]
Introduction: Adaptive joins are an exciting feature in PostgreSQL that dynamically adjust the join method during query execution to optimize performance. This article explores adaptive joins in PostgreSQL, their benefits, and how they can improve […]
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