Apr 29, 2026
VARIANT Support, Interactive Parquet File TUI: Hardwood 1.0.0.Beta2 Is Out
I am happy to announce the release of Hardwood 1.0.0.Beta2!
The latest version of this new parser for Apache Parquet comes with support for VARIANT columns, an interactive text-based UI (TUI) for examining and analysing the structure of Parquet files, significantly improved performance, more efficient reading of files from object storage, and much more.
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Apr 2, 2026
Hardwood Reaches Beta: S3, Predicate Push-Down, CLI, and More
I am pleased to announce the release of Hardwood 1.0.0.Beta1!
Hardwood is a new parser for Apache Parquet, optimized for minimal dependencies and great performance. Since the project’s initial release just a few weeks back, a small yet very active community has come together and evolved Hardwood significantly. Today, we are shipping an S3 backend, allowing to parse files directly from object storage, predicate pushdown for both local and remote files, Avro bindings, a CLI for inspecting Parquet files, and much more. We’re also excited to launch a website for the project, hardwood.dev, which contains the documentation and API reference.
Let’s dig in.
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Feb 26, 2026
Hardwood: A New Parser for Apache Parquet
Today, it’s my great pleasure to announce the first public release of Hardwood, a new parser for the Apache Parquet file format, optimized for minimal dependencies and great performance.
Hardwood is open-source (Apache License 2.0) and supports Java 21 or newer. You can grab it from Maven Central and start parsing your Parquet files with ease and efficiency.
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Dec 7, 2025
You Gotta Push If You Wanna Pull
Historically, data management systems have been built around the notion of pull queries: users query data which, for instance, is stored in tables in an RDBMS, Parquet files in a data lake, or a full-text index in Elasticsearch. When a user issues a query, the engine will produce the result set at that point in time by churning through the data set and finding all matching records (oftentimes sped up by utilizing indexes).
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Nov 25, 2025
On Idempotency Keys
In distributed systems, there’s a common understanding that it is not possible to guarantee exactly-once delivery of messages. What is possible though is exactly-once processing. By adding a unique idempotency key to each message, you can enable consumers to recognize and ignore duplicate messages, i.e. messages which they have received and successfully processed before.
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Nov 20, 2025
Building a Durable Execution Engine With SQLite
Lately, there has been a lot of excitement around Durable Execution (DE) engines. The basic idea of DE is to take (potentially long-running) multi-step workflows, such as processing a purchase order or a user sign-up, and make their individual steps persistent. If a flow gets interrupted while running, for instance due to a machine failure, the DE engine can resume it from the last successfully executed step and drive it to completion.
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Nov 3, 2025
"You Don't Need Kafka, Just Use Postgres" Considered Harmful
Looking to make it to the front page of HackerNews? Then writing a post arguing that "Postgres is enough", or why "you don’t need Kafka at your scale" is a pretty failsafe way of achieving exactly that. No matter how often it has been discussed before, this topic is always doing well. And sure, what’s not to love about that? I mean, it has it all: Postgres, everybody’s most favorite RDBMS—check! Keeping things lean and easy—sure, count me in! A somewhat spicy take—bring it on!
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Sep 17, 2025
Let's Take a Look at... Lower Java Tail Latencies With ZGC
Java 25 was released earlier this week, and it is the first Java release with long-term support (LTS) which ships with Generational ZGC as the one (and only) flavor of the ZGC garbage collector. ZGC itself is a relatively new concurrent collector, originally added in Java 11.
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Aug 5, 2025
Postgres Replication Slots: Confirmed Flush LSN vs. Restart LSN
Replication slots in Postgres keep track of how far consumers have read a replication stream. After a restart, consumers—either Postgres read replicas or external tools for change data capture (CDC), like Debezium—resume reading from the last confirmed log sequence number (LSN) of their replication slot. The slot prevents the database from disposing of required log segments, allowing safe resumption after downtime.
In this post, we are going to take a look at why Postgres replication slots don’t have one but two LSN-related attributes: restart_lsn and confirmed_flush_lsn. Understanding the difference between the two is crucial for troubleshooting replication issues, optimizing WAL retention, and avoiding common pitfalls in production environments.
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Jul 17, 2025
Converting Future to CompletableFuture With Java Virtual Threads
Since Java 8, the CompletableFuture API provides a convenient way for performing asynchronous operations in a functional, composable way. This makes it very simple to call some long-running methods—for instance involving external I/O—asynchronously and process each result as soon as it is available, without blocking on any threads:
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