Tweak some code, add some docs, refs #14

lib/sequel/extensions/make_readyable.rb

@@ -1,11 +1,41 @@
 module Sequel
   module MakeReadyable
+    ##
+    # This method is primarily geared towards Spark SQL-based databases.
+    #
+    # Given some options, prepares a set of views to represent a set
+    # of tables across a collection of different schemas and external,
+    # unmanaged tables.
+    #
+    #   DB.make_ready(use_schema: :schema)
+    #   # => USE `schema`
+    #
+    # When using search_path, tables from previous schema override tables
+    # from the next schema.  This is analogous to the way Unix searches 
+    # the PATH variable for programs.
+    #
+    # Assuming the following tables: schema1.a, schema2.a, schema2.b
+    #
+    #   DB.make_ready(search_path: [:schema1, :schema2])
+    #   # => CREATE TEMPORARY VIEW `a` AS SELECT * FROM `schema1`.`a;`
+    #   # => CREATE TEMPORARY VIEW `b` AS SELECT * FROM `schema2`.`b;`
+    #
+    # When using Pathnames, the extension on the file becomes the format
+    # to try to read from the file.  
+    #
+    #   DB.make_ready(search_path: [Pathname.new("c.parquet"), Pathname.new("d.orc")])
+    #   # => CREATE TEMPORARY VIEW `c` USING parquet OPTIONS ('path'='c.parquet')
+    #   # => CREATE TEMPORARY VIEW `d` USING orc OPTIONS ('path'='d.orc')
+    #
+    # @param [Hash] opts the options used to prepare the database
+    # @option opts [String] :use_schema The schema to be used as the primary schema
+    # @option opts [Array] :search_path A set of sympbols (to represent schemas) or Pathnames (to represent externally managed data files)
     def make_ready(opts = {})
-      self.extension :usable
       ReadyMaker.new(self, opts).run
     end
   end
 
+  private 
   class ReadyMaker
     attr_reader :db, :opts
 
@@ -16,6 +46,7 @@ def initialize(db, opts)
 
     def run
       if opts[:use_schema]
+        db.extension :usable
         db.use(opts[:use_schema])
       end
       only_tables = Array(opts[:only])