tonsky / tonsky/datascript

Implement ICounted for Iter

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Dominant language
Clojure
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Description

An efficient count could allow other optimizations in datascript.

Currently a count on an Iter iterates manually through the sequence which is slow.

A pretty fast one is:

(defn iter-count
  "Fast counting of btset Iter (from datoms)"
  [iter]
  (loop [cnt 0, iter iter]
    (if iter
      (recur (+ cnt (-count (btset/iter-chunk iter))) (btset/iter-chunked-next iter))
      cnt)))

which uses the chunking. A similar and even faster -count should be implemented in btset. This is probably an easy one for outsiders.

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First steps

  1. Read the whole issue, then the project's contributing guide.
  2. Comment on the issue to say you are picking it up — it saves two people doing the same work.
  3. Fork the repository and make your change on a branch.
  4. Open a pull request that references the issue number.

Research direction

Locate the Iter and btset implementations, then inspect the existing chunking methods and protocol implementations. Done means Iter supports an efficient ICounted/-count path based on chunking, with the repository's existing checks still passing.

Written by the indexing model from the issue text.

Assessment

Tech stack
clojure
Domain
databases
Issue type
Feature
Difficulty
3/5
Estimated time
1-2 days
Activity status
Stale
Clarity
Mostly clear
Newbie friendliness
45/100

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