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Asked: 2026-05-11T09:35:46+00:00

What are your methods of linking data spread over multiple databases architectures (think MySQL

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What are your methods of linking data spread over multiple databases architectures (think MySQL vs PostgreSQL etc), into a single application?

Would you create giant hashtables/arrays to match content against one another? Are there other, more effective and less memory-consuming options for doing this?

If you were to use data both from a MySQL & PostgreSQL source, with no way of converting one DB to the other (application constraints, lack of time, lack of knowledge, … ), how would you go about it?

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  1. At least in the case of MySQL, you can use data from multiple databases in a single query anyway, provided the databases are hosted by the same MySQL Server instance. You can distinguish tables from different databases by qualifying the table with a schema name:

    CREATE TABLE test.foo (id SERIAL PRIMARY KEY) TYPE=InnoDB;  CREATE DATABASE test2; CREATE TABLE test2.bar (foo_id BIGINT UNSIGNED,      FOREIGN KEY (foo_id) REFERENCES test.foo(id)) TYPE=InnoDB;  SELECT * FROM test.foo f JOIN test2.bar b ON (f.id = b.foo_id);

    In PostgreSQL, you can also qualify table references with a schema name. I’m not sure if you can create foreign key constraints across databases, though.

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