pgxlog

pgxlog is an open-source tool designed to extract and process changes recorded in PostgreSQL's write-ahead log (WAL) for auditing, analytics, and replication monitoring. It focuses on decoding WAL records via PostgreSQL's logical decoding feature and presenting the results in structured formats for downstream consumption.

Key features include real-time WAL streaming from a logical decoding slot, support for multiple output targets such as files, standard output, or network sinks, configurable filtering by database, table, or event type, and pluggable decoders that can emit JSON, CSV, or custom formats. The tool is designed to be lightweight and network-friendly, with low memory footprint and batched writes.

Under the hood, pgxlog runs as a daemon or command-line client that connects to a PostgreSQL server, creates or uses an existing logical decoding replication slot, and subscribes to WAL changes. It decodes changes using a built-in set of parsers and can deliver both DML row-level changes and schema-altering events depending on the configured output.

Typical use cases include database auditing, change-data capture, debugging replication lag, and feeding analytics pipelines or external systems (such as message queues or search indexes). It is intended to complement native PostgreSQL replication by offering a higher-level, human- or machine-readable stream of events.

See also: PostgreSQL, WAL, replication slot, logical decoding, Debezium, change data capture.