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Best Practices for TimescaleDB Massive Delete Operations

Welcome to the second part of our TimescaleDB best practices series! In the first part, we explored how to perform massive backfill operations efficiently, sharing techniques to optimize performance and avoid common pitfalls. If you haven’t had a chance to read the first part yet, you can check it out using this link In today's blog, we will discuss another crucial aspect of time-series data management: massive delete operations. As your data grows over time, older records often lose their relevance but continue to occupy valuable disk space, potentially increasing storage costs and might degrade the performance if not managed well.  Let's walk through some strategies to clean up or downsample aged data in TimescaleDB, helping you maintain a lean, efficient, and cost-effective database.
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How to Safely Perform Backfill Operations in TimescaleDB

Backfilling data into a TimescaleDB hypertable in production can be very tricky, especially when automated processes like compression policies are involved. From past experience, we have seen that if backfill operations aren’t handled properly, they can interfere with these automated tasks, sometimes causing them to stop working altogether.  This blog covers a safer and more reliable approach to backfilling hypertables, along with best practices to prevent disruptions to compression and other background processes. What is a Backfill Operation? Backfilling means adding old or missing data into the database table after some time has already passed.  Imagine you are collecting temperature readings every hour, but your system was down for a day and didn’t save any data. Later, you get that missing data from the local storage of the device or cloud storage, and want to put it back in the right hypertable, which is called backfilling.  In TimescaleDB, this is common with time-series data, but it needs to be done carefully. That’s because TimescaleDB might already be doing things in the background, like compressing old data to save space. If we are not careful, backfilling can mess up these automatic tasks.
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Finding Bottlenecks and Avoiding Over-Optimization via Explain Plans

Performance optimization in a production database is important, but trying to over-optimize can make things more complicated without real improvements. In this post, I’ll share two very basic EXPLAIN ANALYZE outputs from a production system. A user asked us to help optimize these queries. I've changed the table and column names for privacy. We will look at how to spot slow parts of a query, improve performance the right way, and avoid unnecessary tuning. Plan A: Identifying and Resolving a Bottleneck Execution Plan A (Before Optimization) Nested Loop (cost=1000.42..25607.38 rows=1 width=129) (actual time=78.521..90.445 rows=0 loops=1) -> Gather (cost=1000.00..25598.95 rows=1 width=65) (actual time=78.520..90.443 rows=0 loops=1) Workers Planned: 2 Workers Launched: 2 -> Parallel Seq Scan on <table_1> e (cost=0.00..24598.85 rows=1 width=65) (actual time=75.351..75.351 rows=0 loops=3) Filter: ((<column_1>) = '<date_value>'::date) AND ((<column_2>)::text = '<event_type>'::text) Rows Removed by Filter: <number_removed_rows> -> Index Scan using <index_name> on <table_2> a (cost=0.42..8.43 rows=1 width=41) (never executed) Index Cond: ((<column_3>)::text = (<column_4>)::text) Filter: ((<column_5>)::text = '<default_value>'::text) Planning Time: 0.466 ms Execution Time: 90.580 ms
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Important PostgreSQL Parameters: Understanding Their Importance and Recommended Values

Have you ever experienced your database slowing down as the amount of data increases? If so, one important factor to consider is tuning PostgreSQL parameters to match your specific workload and requirements.  PostgreSQL has many parameters because it is designed to be highly flexible and customizable to meet a wide range of use cases and workloads. Each parameter allows you to fine-tune different aspects of the database, such as memory management, query optimization, connection handling, and more. This flexibility helps database administrators to optimize performance based on hardware resources, workload requirements, and specific business needs. In this blog, I will cover some of the important PostgreSQL parameters, explain their role, and provide recommended values to help you fine-tune your database for better performance and scalability.  Memory-Related Parameters Memory-related parameters in PostgreSQL control how the database allocates and manages memory. Tuning these settings is important for improving query performance and preventing resource bottlenecks. Name: work_mem Description: Sets the maximum amount of memory used by internal operations like sorts and hashes before writing to disk. Increasing it can improve performance for complex queries Default: 4MB Recommended: Typically, setting work_mem to 1-2% of the total system's available memory is recommended, i.e., if the total system memory is 256 GB, assign 3 to 5 GB for work_mem. Note: This may lead to higher memory usage for operations that involve sorting. Name: shared_buffers Description: Determines the amount of memory allocated for caching database data. Default: 128MB Recommendation: Typically, setting shared_buffers to 25-40% of the total system memory is recommended, i.e., if the total system memory is 256 GB, assign 64-102 GB for shared_buffers. Name: maintenance_work_mem Description: Specifies the amount of memory used for maintenance operations like VACUUM, CREATE INDEX, and ALTER TABLE. Increasing it can speed up these operations. Default: 64MB Recommendation: it's recommended to set 5-10% of the total system memory, i.e., if the total system memory is 256 GB, assign 13 to 26 GB for maintenance_work_mem.
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A Guide to Restoring a PostgreSQL Database from Disaster Using Azure Flexible Server

Backups are crucial for any mission-critical application as they protect against unforeseen disasters. Regular backups help minimize the Recovery Point Objective (RPO), allowing systems to recover quickly with minimal data loss. However, it's equally important to store backups safely. If backups are kept in the same location as the primary site and something goes wrong, you may have no way to recover, leading to complete data loss. To reduce these risks, many organizations choose fully managed servers to host their databases. One popular option is Azure Flexible Server for PostgreSQL, which offers a reliable, scalable, and managed solution.  Azure provides 3 levels of redundancy in three different ways, and not only that, you can recover backups using these same three methods. These are Locally Redundant Storage Zone Redundant Storage Geo Redundant Each level of redundancy offers unique advantages when it comes to restoring backups. In today's blog, we will explore all three types of backups and recovery methods. We will dive into the differences between each type and learn how to restore your backup if your primary site goes down.
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What Happens Behind the Scenes When You Modify a Row in PostgreSQL?

Data is often called the new gold, and databases are where we store and manage this precious resource as it constantly changes and grows. At first glance, updating data might seem like a simple task—just modify a row.  But behind the scenes, it’s more complex to ensure that data remains consistent and accessible. In today’s blog, I’ll answer some frequently asked questions from our customers and dive into why PostgreSQL relies on a process called VACUUM to efficiently manage data updates. Updating a row in PostgreSQL isn’t as straightforward as directly changing the existing data. Instead, PostgreSQL avoids in-place updates, meaning it doesn’t overwrite rows directly.  But what does this actually mean?  When an update occurs, PostgreSQL creates a new row, inserts the updated data there, and marks this new row as the latest version. The old row, meanwhile, is flagged as obsolete row. A similar process applies to deletes, where rows are marked as outdated rather than removed immediately.  This raises an interesting question on why did PostgreSQL choose this more complex approach for handling updates and deletes?  The answer lies in its design philosophy, which is rooted in Multi-Version Concurrency Control (MVCC). MVCC ensures data consistency and allows for high concurrency. What is Multi-Version Concurrency Control (MVCC)? Multi-Version Concurrency Control (MVCC) allows PostgreSQL to manage multiple transactions at once, enabling consistent data views for each transaction without interference. Imagine a library with a single book titled The Ultimate Guide to Databases.  Without Multi-Version Concurrency Control (MVCC), if two people want to check out the book at the same time, one would have to wait for the other to finish reading it. This is similar to a traditional database where transactions can block each other, preventing simultaneous access. With MVCC, the process works differently. When the first person checks out the book, the library creates a copy just for them. The second person can also check out the book at the same time, but they receive their own copy. Both individuals can read and make notes in their respective copies without affecting the other’s experience. Once they’re done, they return the copies, and the library can clean them up for future use. In this analogy, the book represents a data record in a database, and the copies of the book are like different versions of that data.  MVCC allows PostgreSQL to create and manage multiple versions of data, enabling multiple transactions to access and modify the data concurrently without interfering with each other. This ensures that each transaction gets a consistent view of the data while allowing for high performance and concurrency. However, just like the library ends up with multiple copies of the book that are no longer being read, PostgreSQL ends up with versions of the data that are no longer needed, called dead tuples.  These dead tuples are like outdated copies of the book that no one is checking out anymore. Over time, as more transactions occur, these dead tuples accumulate, taking up space and potentially slowing down the system. This is where the process of vacuuming comes in—just like the library regularly clears out old, unused books to make room for new ones, PostgreSQL uses vacuuming to clean up dead tuples, reclaim storage, and maintain optimal performance.
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Scenarios That Trigger Autovacuum in PostgreSQL

PostgreSQL is widely known for its Multi-Version Concurrency Control (MVCC) model, which allows multiple transactions to occur simultaneously without interfering with each other.  However, one side effect of MVCC is the creation of dead tuples—old versions of data rows that are no longer needed but still occupy space.  Dead tuples also lead to a phenomenon known as table bloat, which refers to the excessive unused space in a table caused by dead tuples that haven't been cleaned up, resulting in inefficient storage and reduced performance To address the issues of dead tuples and table bloat, autovacuum comes into play. It's an automatic process designed to clean up these dead tuples and maintain optimal database performance. In this blog, we will explore the main situations when autovacuum should run:
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Offline PostgreSQL Installation on RHEL 9: Solving the No Internet Challenge

PostgreSQL is one of the most loved databases, especially by developers, for its simplicity, easy configurations, and massive community support. It's an open-source powerhouse known for handling everything from small projects to large-scale applications.  While major cloud providers, like AWS, Google, and Microsoft offer robust solutions for hosting databases on the cloud, not all businesses can or want to go this route Many companies, choose to store their databases in secure, closed environments—machines without internet access or outside the cloud. This is often done to maintain tight control over sensitive data and to meet strict security requirements. However installing PostgreSQL in a restricted, offline environment can be a real challenge, as it limits access to typical installation tools.  Recently, I worked on a client project with a similar setup—a secure, offline environment without internet access—where we needed to install and configure PostgreSQL from scratch. If you’re facing the challenge of setting up PostgreSQL in a closed environment, this blog will guide you through the process step-by-step.
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Implementing Bi-Directional Replication in PostgreSQL

In today's fast-paced digital world, ensuring that your data is always up-to-date and accessible is crucial. For businesses using PostgreSQL, replication is a key feature that helps achieve this. While many are familiar with streaming replication, bi-directional replication offers unique advantages that can enhance data availability and reliability. In this blog post, we'll explore what bi-directional replication is, how it differs from streaming replication, and provide a practical example to setup bi directional replication in PostgreSQL
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Transform PostgreSQL into a Columnar Database Using Citus

Columnar databases are transforming the way we handle large datasets by storing data in columns rather than rows. This approach enhances performance, especially for analytical queries, by allowing faster data retrieval and efficient storage. As businesses generate more data than ever, understanding the benefits of columnar databases becomes crucial. In this blog, we'll explore how these databases work, their advantages over traditional row-based systems, and why they are becoming a popular choice for data-driven organizations.
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