In PostgreSQL, a COMMIT statement is used to finalize a transaction and make its changes permanent in the database. When a COMMIT statement is executed, the following things happen internally in PostgreSQL: After a transaction […]
In MySQL, if the server crashes after an update and the transaction was not committed, the changes made by the transaction will be rolled back during the crash recovery process. This is because MySQL uses […]
Using SELECT * can be bad for SQL performance for several reasons, including the following: Overall, it is best practice to only select the columns that are needed for a query, rather than using SELECT […]
PostgreSQL uses latches to provide synchronization between different threads accessing shared resources. Latches are lightweight and efficient mechanisms that provide mutual exclusion between threads. Here is a table describing all the PostgreSQL latches, their purpose, […]
PostgreSQL has several configuration parameters that control its memory usage. Here is a detailed description of some of the most important memory-related parameters: It is important to monitor the memory usage of the database process […]
PostgreSQL 15 introduces a new parallel query feature called “Partitionwise Joins” which can improve the performance of queries involving large tables. Here’s how to implement parallel queries using this feature: Here’s an example query that […]
Checkpoint queues can have a significant impact on the recovery process in PostgreSQL. Checkpoints are a mechanism that PostgreSQL uses to write dirty data from memory to disk, in order to ensure that the data […]
In PostgreSQL, undo blocks are implemented using a mechanism called Multi-Version Concurrency Control (MVCC), which allows multiple versions of a row to exist in the database at the same time. When a transaction updates or […]
Deadlock is a situation where two or more transactions are blocked, waiting for each other to release locks that they hold. In PostgreSQL, deadlocks can occur in several scenarios, such as: To prevent deadlocks in […]
The impact of ordered versus random index insertion in InnoDB depends on several factors, including the size and complexity of the table, the frequency of inserts, and the workload of the database. Ordered index insertion […]
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