PostgreSQL DBA

What is parallel querying in PostgreSQL? Parallel querying is a technique in PostgreSQL that allows you to create query plans that can leverage multiple CPUs to answer queries more efficiently. This technique is particularly well-suited when the query involves scanning a lot of data but returning a few rows, for example, aggregate calculations.

https://www.postgresql.org/docs/current/geqo-pg-intro.html Genetic Query Optimization (GEQO)

How can you handle errors in PostgreSQL? There are two main ways to address errors in PostgreSQL: Callback functions can be developed to handle warning and error conditions. In this case, you can specify a certain behavior in case of errors and warnings in your queries using the WHENEVER command. Detailed information about the error or warning can be obtained from the sqlca variable. This variable provides detailed information when errors and warnings arise during execution.

How can you improve query performance in PostgreSQL? There are multiple strategies to increase query performance, including: Using indexing, especially in queries that involve WHERE clauses; Writing efficient SQL statements to reduce processing overhead, for example, by avoiding unnecessary columns in the SELECT statement. Implementing partitioning for large tables. Optimizing memory usage by tuning server parameters to match hardware specifications. Especially when dealing with large databases, improving your query performance is crucial to avoid undesired bottlenecks. Check out our Improving Query Performance in PostgreSQL Course to become a query wizard.

What commands are used to control transactions in PostgreSQL? ans: There are 3 main commands to control transactions in PostgreSQL: BEGIN TRANSACTION or simply BEGIN: To start a transaction. COMMIT or END TRANSACTION: To save the changes. The COMMIT command saves all transactions to the database since the last COMMIT or ROLLBACK command. ROLLBACK: It’s used to undo transactions that have not already been saved to the database.

What is partitioning in PostgreSQL? It’s the process of splitting a large table into smaller pieces. It can be done through several methods, including range partitioning, list partitioning, and hash partitioning.

What is an index in PostgreSQL? An index is a special data structure related to a table and used for storing its important parts and enabling faster data search and retrieval. This is achieved by creating a sorted data structure that allows PostgreSQL to locate rows more quickly compared to a full table scan. Indexes are especially efficient for large databases, where they significantly enhance query performance.

What is Multi-version Concurrency Control in PostgreSQL? Multi-version Concurrency Control or MVCC is an advanced technique in PostgreSQL. It enhances database performance in multi-user scenarios. This means that while querying a database each transaction sees a snapshot of data (a database version) as it was some time ago, regardless of the current state of the underlying data. This protects the transaction from viewing inconsistent data that could be caused by (other) concurrent transaction updates on the same data rows. Put simply, MVCC creates multiple versions of a single database record, enabling various transactions to access different versions of one database record without conflicting with one another, thereby allowing simultaneous transitions.

What is a constraint in PostgreSQL? Ans: A set of conditions defining the type of data that can be input into each column of a table. Constraints are used to ensure data integrity in a table and prevent undesired actions.

https://dev.to/nightbird07/exploring-the-limitations-of-postgres-partitioning-lessons-learned-and-best-practices-5cj9 Exploring the Limitations of Postgres Partitioning: Lessons Learned and Best Practices

https://sparktpoint.com/postgresql-partition-by/ PARTITION BY in PostgreSQL

https://www.postgresql.fastware.com/postgresql-insider-prt-ove Partitioning

https://www.timescale.com/learn/when-to-consider-postgres-partitioning When to Consider Postgres Partitioning

https://rasiksuhail.medium.com/guide-to-postgresql-table-partitioning-c0814b0fbd9b#:~:text=Hash%20partitioning%20in%20PostgreSQL%20is,Partition%20makes%20querying%20faster. Guide to PostgreSQL Table Partitioning

https://www.cybertec-postgresql.com/en/how-to-corrupt-your-postgresql-database/ How to corrupt your PostgreSQL database

https://www.highgo.ca/2021/01/27/avoiding-identifying-and-dealing-with-postgresql-database-corruption-part-1/ Avoiding, Identifying, and dealing with PostgreSQL database corruption

https://www.linkedin.com/pulse/understanding-data-corruption-postgresql-shyam-kumar-9kvwc Understanding Data Corruption in PostgreSQL

https://akashcsharma.medium.com/demystifying-database-internals-part-2-deep-dive-into-storage-engine-of-dbms-episode-i-paging-2f748a078d22 Deep dive into Storage Engine of DBMS Episode I(Paging, Buffer Pool Manager, Write Ahead Log)