How not to structure database-backed web apps: performance bugs in the wild

Re:How not to structure database-backed web apps: performanc... by mpweiher on Thursday June 28, 2018 @05:25AM (#17415320)

That's one thing I love about Gemstone/Smalltalk.

In Smalltalk, you would write such a query as:

   (cars select: [ :car | car insurance endDate < now ]) size.

(There probably is a shortcut for just counting the elements, though admittedly you have to have each car for the query).

So what Gemstone does is that when cars is a DB collection, it interprets the block and turns it into a query. So the code for iterating in-memory and the code for doing an optimized query is the same.

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Re:How not to structure database-backed web apps: performanc... by vidarh on Thursday June 28, 2018 @05:56AM (#17415480)

In Ruby, using Sequel:

    DB[:cars].where { insurance_end_date < Time.now }.count

(replacing "Time.now" with Sequel.function("NOW") if you want server side, or whatever date/time formatting function you want that'll return time/date in your desired format client side; client side it'll be evaluated once)

I think most ORMs can do a reasonable job at this in languages where you have sufficient flexibility in overloading behaviour.

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