datascript 2022-07-26 | Slack Archive

imre08:07:47

I’m trying to optimize a clojure (jvm) service that uses some datascript (1.3.8) entities on its hot path. They are returned by a query and then later we use them as we would use nested maps:

(d/q '[:find ?entity ; and other stuff
       :where
       ; other clauses
       [(datascript.core/entity $ ?foo) ?entity]]
     db)

(-> entity :foo/bar :foo.bar/baz)
(-> entity :qux/_some-reverse-lookup :foo/bar :foo.bar/baz)
(contains? entity :foo/bar)
;; etc

We found through flame graphs that a noticeable amount of time is spent in these keyword lookups (more specifically in lookup-entity) despite the built-in caching. I feel like we are missing a better pattern here and was wondering what we could do at query time to speed up later lookups within the entity?

imre09:07:32

I guess pull syntax is going to be my friend 🙂

Niki10:07:28

Yes pull might perform better. Also see if you can do without query (via direct index lookup), as queries are doing some extra work you might not need (depends on their complexity, of course)

imre10:07:54

Thank you. In our case the initial query cost doesn’t matter that much as the result can be and is memoized. It’s the repeated use of data returned by the query that we see costly

2022-07-26

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