Zero-downtime Postgres migrations – the hard parts

Re:Zero-downtime Postgres migrations – the hard parts by spotman on Thursday May 28, 2015 @01:00AM (#9616140)

Curious, is the:

  SELECT DISTINCT(email) FROM parent;

The actual query you run in production, or similar enough? That could be a very expensive query with a very large amount of rows, even if indexed. (Large, being in the multi millions, depending on hardware). Might make more sense to run something like that on a reporting slave.

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Re:Zero-downtime Postgres migrations – the hard parts by Sinjo on Thursday May 28, 2015 @05:33AM (#9616944)

That was a fabricated example, rather than something plucked from our codebase. It's the sort of query we avoid running on our production database.

I agree with your approach though. Our data analysis runs elsewhere.

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