Module: Sequel::Snowflake::DatasetMethods

Included in:
Dataset
Defined in:
lib/sequel/adapters/shared/snowflake.rb

Instance Method Summary collapse

Instance Method Details

#explain(opts = OPTS) ⇒ Object

Return an array of strings specifying a query explanation for a SELECT of the current dataset. The options (symbolized, in lowercase) are:

JSON: JSON output is easier to store in a table and query.
TABULAR (default): tabular output is generally more human-readable than JSON output.
TEXT: formatted text output is generally more human-readable than JSON output.



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# File 'lib/sequel/adapters/shared/snowflake.rb', line 12

def explain(opts=OPTS)
  # Load the PrettyTable class, needed for explain output
  Sequel.extension(:_pretty_table) unless defined?(Sequel::PrettyTable)

  explain_with_format = if opts[:tabular]
    "EXPLAIN USING TABULAR"
  elsif opts[:json]
    "EXPLAIN USING JSON"
  elsif opts[:text]
    "EXPLAIN USING TEXT"
  else
    "EXPLAIN"
  end

  ds = db.send(:metadata_dataset).clone(:sql=>"#{explain_with_format} #{select_sql}")
  rows = ds.all
  Sequel::PrettyTable.string(rows, ds.columns)
end