[openstreetmap/openstreetmap-website] performance reduced when updating/migrating (#2980)

Tom Hughes notifications at github.com
Tue Nov 24 19:26:13 UTC 2020


Yes that's definitely a valid test - of how fast your database can table scan `current_nodes` but it says absolutely nothing about the kind of queries involved in running the map call which involves joining a number of tables and (hopefully) choosing to use indexes instead of table scanning.

Please, looking at your log, see what queries are slow, and try analysing them.

Also, seek help from postgres experts if you need help with postgres.

If you really want to claim it's our code then run the same version on both machines so the results are comparable.

First rule of debugging - change one thing at a time. You have apparently changed hardware, database and rails code all in one go and you're now guessing which of those variables is the problem. Try and eliminate some of those variables to see where the problem is. A good start is to run the older rails code on the new machine or the new rails code on the old machine because that's easy to do.

That said, the API code in this repository hasn't changed significantly in years because, as I say, we don't actually use it!

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