Initial implementation of MakeReadyable

Gemfile

@@ -2,3 +2,7 @@ source 'https://rubygems.org'
 
 # Specify your gem's dependencies in sequelizer.gemspec
 gemspec
+
+group :test do
+  gem "sequel-hexspace", github: "outcomesinsights/sequel-hexspace", branch: "master"
+end

lib/sequel/extensions/make_readyable.rb

@@ -0,0 +1,76 @@
+module Sequel
+  module MakeReadyable
+    def make_ready(opts = {})
+      self.extension :usable
+      ReadyMaker.new(self, opts).run
+    end
+  end
+
+  class ReadyMaker
+    attr_reader :db, :opts
+
+    def initialize(db, opts)
+      @db = db
+      @opts = opts
+    end
+
+    def run
+      if opts[:use_schema]
+        db.use(opts[:use_schema])
+      end
+      only_tables = Array(opts[:only])
+      created_views = (Array(opts[:except]) || [])
+      (opts[:search_path] || []).each do |schema|
+        source = get_source(db, schema)
+        tables = source.tables(schema: schema) - created_views
+        tables &= only_tables unless only_tables.empty?
+        tables.each do |table|
+          create_view(source, table, schema)
+          created_views << table
+        end
+      end
+    end
+
+    def create_view(source, table, schema)
+      if schema.to_s =~ %r{/}
+        source.create_view(table, temp: true)
+      else
+        source.create_view(table, db[Sequel.qualify(schema, table)], temp: true)
+      end
+    end
+
+    def get_source(db, schema)
+      if schema.to_s =~ %r{/}
+        FileSourcerer.new(db, Pathname.new(schema))
+      else
+        db
+      end
+    end
+
+    class FileSourcerer
+      attr_reader :db, :schema
+      def initialize(db, schema)
+        @db = db
+        @schema = schema
+      end
+
+      def tables(opts = {})
+        [schema.basename(".*").to_s.to_sym]
+      end
+
+      def create_view(table, opts = {})
+        db.create_view(table, {
+          temp: true,
+          using: format,
+          options: { path: schema.expand_path }
+        }.merge(opts))
+      end
+
+      def format
+        schema.extname[1..-1]
+      end
+    end
+  end
+
+  Database.register_extension(:make_readyable, MakeReadyable)
+end

test/lib/sequel/extensions/test_make_readyable.rb

@@ -0,0 +1,81 @@
+require_relative "../../../test_helper"
+require "fileutils"
+require "pathname"
+require "sequel"
+require "sequel/extensions/make_readyable"
+
+class TestUsable < Minitest::Test
+  def setup
+    # These features are mostly intended for Spark, but sqlite is a close enough
+    # mock that we'll just roll with it
+    @db = Sequel.mock(host: :spark)
+    @db.extension :make_readyable
+    def @db.tables(opts = {})
+      case opts[:schema]
+      when :schema1
+        [:a]
+      when :schema2
+        [:a, :b]
+      when :schema3
+        [:a, :b]
+      end
+    end
+  end
+
+  def test_should_call_use_schema
+    @db.make_ready(use_schema: :some_schema)
+    assert_equal(["USE `some_schema`"], @db.sqls)
+  end
+
+  def test_should_create_views_based_on_tables_in_search_paths
+    @db.make_ready(search_path: [:schema1, :schema2, :schema3])
+    assert_equal([
+      "CREATE TEMPORARY VIEW `a` AS SELECT * FROM `schema1`.`a`",
+      "CREATE TEMPORARY VIEW `b` AS SELECT * FROM `schema2`.`b`"
+    ], @db.sqls)
+  end
+
+  def test_should_create_views_based_on_tables_in_search_paths_accepts_except
+    @db.make_ready(search_path: [:schema1, :schema2, :schema3], except: :a)
+    assert_equal([
+      "CREATE TEMPORARY VIEW `b` AS SELECT * FROM `schema2`.`b`"
+    ], @db.sqls)
+  end
+
+  def test_should_create_views_based_on_tables_in_search_paths_accepts_only
+    @db.make_ready(search_path: [:schema1, :schema2, :schema3], only: :b)
+    assert_equal([
+      "CREATE TEMPORARY VIEW `b` AS SELECT * FROM `schema2`.`b`"
+    ], @db.sqls)
+  end
+
+  def test_should_create_views_based_on_path
+    dir = Pathname.new(Dir.mktmpdir)
+    a_file = dir + "a.parquet"
+    b_file = dir + "b.parquet"
+    FileUtils.touch(a_file.to_s)
+    FileUtils.touch(b_file.to_s)
+
+    @db.make_ready(search_path: [:schema1, a_file, b_file, :schema2])
+    sqls = @db.sqls.dup
+    assert_equal("CREATE TEMPORARY VIEW `a` AS SELECT * FROM `schema1`.`a`", sqls[0])
+    assert_match(%r{CREATE TEMPORARY VIEW `b` USING parquet OPTIONS \('path'='/tmp/[^/]+/b.parquet'\)}, sqls[1])
+  end
+
+  def test_should_create_views_format_based_on_path
+    dir = Pathname.new(Dir.mktmpdir)
+    a_file = dir + "a.parquet"
+    b_file = dir + "b.delta"
+    c_file = dir + "c.csv"
+    FileUtils.touch(a_file.to_s)
+    FileUtils.touch(b_file.to_s)
+    FileUtils.touch(c_file.to_s)
+
+    @db.make_ready(search_path: [a_file, b_file, c_file])
+    sqls = @db.sqls.dup
+    assert_match(%r{CREATE TEMPORARY VIEW `a` USING parquet OPTIONS \('path'='/tmp/[^/]+/a.parquet'\)}, sqls[0])
+    assert_match(%r{CREATE TEMPORARY VIEW `b` USING delta OPTIONS \('path'='/tmp/[^/]+/b.delta'\)}, sqls[1])
+    assert_match(%r{CREATE TEMPORARY VIEW `c` USING csv OPTIONS \('path'='/tmp/[^/]+/c.csv'\)}, sqls[2])
+  end
+end
+