`unique` works incorrectly with `IndexedFactbase`

[yegor256]

This is my code:

    require 'fbe/fb'
    fb = Factbase.new
    fb = Factbase::IndexedFactbase.new(fb)  # here!
    fb.import(File.binread('1.fb'))
    puts fb.query("(and (eq repository 798641472) (unique issue))").each.to_a.count

If I comment out one line, I get 305 as an output.

With this line I get 59 as an output.

The 1.fb file is here: https://public.zerocracy.com/1.fb

This most probably is related to the changes we've made in #487

[yegor256]

@belfil maybe you can help? This is a critical issue now.

[belfil]

@yegor256 Yes, I'll help.

[belfil]

@yegor256 You're right, there's an error in the unique index.
It currently lacks the necessary execution context to resolve correctly.

Query: (and (eq foo 2) (unique bar))

Without Context

Facts	(eq foo 2)	(unique bar)	Result
{ id: 1, foo: 1, bar: 1 }	—	✅	—
{ id: 2, foo: 2, bar: 1 }	✅	—	—
{ id: 3, foo: 2, bar: 1 }	✅	—	—

With Context

Facts	(eq foo 2)	(unique bar) ctx (eq foo 2)	Result
{ id: 1, foo: 1, bar: 1 }	—	—	—
{ id: 2, foo: 2, bar: 1 }	✅	✅	✅
{ id: 3, foo: 2, bar: 1 }	✅	—	—

Test

  def test_unique_and_context
    fb = Factbase::IndexedFactbase.new(Factbase.new)
    (1..200).each do |i|
      f = fb.insert
      f.id = i
      f.foo = (i <= 50 ? 1 : 2)
      f.bar = 3
    end
    found = fb.query('(and (eq foo 2) (unique bar))').each.to_a
    assert_equal([51], found.map(&:id))
  end

[belfil]

@yegor256 #540

[yegor256]

@rultor release, tag is 0.19.9

[rultor]

@rultor release, tag is 0.19.9

@yegor256 OK, I will release it now. Please check the progress here.