Searching logical shards [closed]

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Is the basic technique behind querying across logical shards just querying them all at the same time and consolidating the results?

There doesn't seem to be any built-in features of MySQL or Postgres that allows you to query across logical shards, so I assume you must query each shard or get some sort of software to sit in front of that database that indexes or queries for you.

Answer 1

MySQL is working on a new technology called MySQL Fabric to do this. It's still in early development (as of this writing). But they apparently intend it to be a built-in feature in MySQL 5.7.

You can also use Shard-Query today. This acts as a proxy to query across all your shards transparently. That is, you can write simple SQL queries as if you didn't have a sharded architecture. Shard-Query rewrites SQL and runs queries against each shard in parallel, then combines the results.

I don't know what, if any, solutions exist for PostgreSQL to automatically query across shards.