PostgreSQL: Joining Heterogeneous Databases is a reality, not a Myth

on YouTube ↗39m

" summary

Claim: PostgreSQL uses SQL‑MED and Foreign Data Wrappers to query and join MySQL, ClickHouse, MongoDB, HDFS and local Postgres tables as if they were local. Demo creates extensions, servers, user mappings and foreign tables, then joins Postgres + MySQL + ClickHouse with subqueries, aggregates and group by and it works. Performance depends on join pushdown (which speeds queries) and on per‑FDW features: mysql_fdw lacks aggregate pushdown so COUNT may pull many rows, while clickhouse_fdw supports complex remote SQL. Connection reuse and basic DML work, but no global two‑phase commit.

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" chapters (4)

1. 0:00Start
2. 3:30APPLICATION ARCHITECTURE 12
3. 9:36APPLICATION ARCHITECTURE 22
4. 33:19CONNECTIONS 12

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