Implement ICounted for Iter

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Assessment

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

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.

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.

Dominant language
Clojure
Stars
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Forks
318
PR merge metrics
No merged PRs in 30d

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