Cloudberry is a fork of Greenplum, which is a fork of Postgres. Greenplum was open sourced in 2015, but when Broadcom acquired the parent company, the source wa

Cloudberry is a fork of Greenplum, which is a fork of Postgres. Greenplum was open sourced in 2015, but when Broadcom acquired the parent company, the source was closed in 2024. Cloudberry is a continuation of that open-source version. Both are based on old versions of Postgres; once you fork Postgres and change the innards, keeping up with the upstream has historically been a chore (you see the same problem with forks like Yugabyte). Cloudberry is not so bad compared to some; they are now up to date with Postgres 14, I believe. In the Cloudberry architecture, as with Greenplum, database tables are partitioned into "segments", which are automatically distributed over a cluster of "segment hosts". A special optimizer called GPORCA figures out how to parallelize the query across these segments and then merge the results back together. The strategy is a classic shared-nothing, single-master architecture, which differs from newer disaggregated compute/data architectures (used especially in "data lake" systems like Delta Lake and Iceberg) in that compute is kept close to the original data; each segment is basically a full database instance, except it just has a subset of the data. GPORCA achieves high speed by "pushing down" operators such as filters and joins down to the individual segments. Greenplum is designed to be used together with a low-latency, high-bandwidth network interconnect, on top of which they use a custom UDP protocol, because each query needs to fan out to potentially a large number of parallel executors. Like ClickHouse, Cloudberry supports columnar table layouts (like CH's MergeTree engine family) as well as the native Postgres row-oriented layout (like CH's Atomic table engine). A difference from CH is that there's not really any single server mode; distributed tables are always distributed by the cluster for you. I can't compare CH's optimizer to Cloudberry's, but I suspect the latter is more sophisticated. I also don't know how performance compares. Cloudberry inherits a lot from Postgres, so I suspect that for non-columnar (OLTP) data performance may be a lot better, but not necessarily for columnar (OLAP) use cases.