Class: ArJdbc::PostgreSQL::ExplainSupport::ExplainPrettyPrinter
- Inherits:
-
Object
- Object
- ArJdbc::PostgreSQL::ExplainSupport::ExplainPrettyPrinter
- Defined in:
- lib/arjdbc/postgresql/explain_support.rb
Overview
:nodoc:
Instance Method Summary collapse
-
#pp(result) ⇒ Object
Pretty prints the result of a EXPLAIN in a way that resembles the output of the PostgreSQL shell:.
Instance Method Details
#pp(result) ⇒ Object
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)
28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 |
# File 'lib/arjdbc/postgresql/explain_support.rb', line 28 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 |