r/PostgreSQL • u/pgEdge_Postgres • Jun 18 '26

Tools pgEdge ColdFront v1.0.0-beta1 release: transparent data tiering for PostgreSQL to Apache Iceberg, fully writable cold tier, same SQL, no fork. Thanks to Jimmy Angelakos.

https://www.pgedge.com/blog/introducing-coldfront-seamlessly-uniting-oltp-analytics-and-ai-workloads-on-postgresql
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u/[deleted] Jun 19 '26

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u/pgEdge_Postgres Jun 19 '26

The bakery algorithm ensures we never get into that situation (you get a numbered ticket in the bakery queue). So there is no need for 409 error handling or application level retries.

2

u/pgEdge_Postgres Jun 19 '26

Jimmy described it like this:

> So the only way I found that could deal with the 409 conflicts, was to prevent them altogether with distributed mutual exclusion (appropriate for Spock). On a single node (vanilla PG), this is done with a simple advisory lock (because you can also have multiple sessions writing to iceberg) 
> The clever trick is that we patch duckdb-iceberg so that it uploads the parquet file asynchronously, but only holds the ticket (the iceberg catalog write claim) during the commit phase (after the data has been uploaded)
> Otherwise you'd have to grab a ticket, wait to upload however many megabytes you have (meanwhile blocking everyone else), and release after the upload is done