method

pp

v3.2.13 - Show latest stable - 0 notes - Class: ExplainPrettyPrinter

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What's this?

pp(result) public

Pretty prints the result of a EXPLAIN in a way that resembles the output of the PostgreSQL shell:

                                  QUERY PLAN
------------------------------------------------------------------------------
 Nested Loop Left Join  (cost=0.00..37.24 rows=8 width=0)
   Join Filter: (posts.user_id = users.id)
   ->  Index Scan using users_pkey on users  (cost=0.00..8.27 rows=1 width=4)
         Index Cond: (id = 1)
   ->  Seq Scan on posts  (cost=0.00..28.88 rows=8 width=4)
         Filter: (posts.user_id = 1)
(6 rows)

Show source

# File activerecord/lib/active_record/connection_adapters/postgresql_adapter.rb, line 551
        def pp(result)
          header = result.columns.first
          lines  = result.rows.map(&:first)

          # We add 2 because there's one char of padding at both sides, note
          # the extra hyphens in the example above.
          width = [header, *lines].map(&:length).max + 2

          pp = []

          pp << header.center(width).rstrip
          pp << '-' * width

          pp += lines.map {|line| " #{line}"}

          nrows = result.rows.length
          rows_label = nrows == 1 ? 'row' : 'rows'
          pp << "(#{nrows} #{rows_label})"

          pp.join("\n") + "\n"
        end

pp

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