sql 2022-05-12 | Slack Archive

Right now I'm getting a vector of results from next-jdbc. Something like this:

[{:column 42} {:column 99} ...]

For what I'm doing, it would be more convenient to have a list. The reason is that I want to use every search result exactly once, deleting every map after it is used. For example:

;; do something with first result
(do-whatever {:column 42})
(recur (rest my-result-seq))

Here is my question: If I do something like this:

(into '() my-result-seq)

(apply list my-result-seq)

does that require O(N) overhead to make the transformation? Or can Clojure do that in O(1)?

dpsutton22:05:31

(doseq [row results] ...) if you don’t care about the result. (run! do-whatever my-result-seq). The type vector vs list is almost meaningless for your purposes

Jim Strieter23:05:19

I don't understand the first half

seancorfield23:05:48

I don't understand the question. What do you mean by "deleting every map"? It's a sequence of hash maps -- aren't you just going to iterate over it?

seancorfield23:05:08

And if you only want to do a single pass over the results and process each row, perhaps plan would be better and then you don't even have the overhead of creating the hash maps or the vector?

2022-05-12

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