Module: SchemaPlusPgIndexes::Middleware::Postgresql::Schema::Indexes

Defined in:
lib/schema_plus_pg_indexes/middleware/postgresql/schema.rb

Instance Method Summary collapse

Instance Method Details

#get_opclass_names(env, opclasses) ⇒ Object 



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# File 'lib/schema_plus_pg_indexes/middleware/postgresql/schema.rb', line 7

def get_opclass_names(env, opclasses)
  @opclass_names ||= {}
  if (missing = opclasses - @opclass_names.keys).any?
    result = env.connection.query(<<-SQL, 'SCHEMA')
    SELECT oid, opcname FROM pg_opclass
    WHERE (NOT opcdefault) AND oid IN (#{opclasses.join(',')})
    SQL
    result.each do |oid, opcname|
      @opclass_names[oid] = opcname
    end
  end
end

#implement(env) ⇒ Object 



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# File 'lib/schema_plus_pg_indexes/middleware/postgresql/schema.rb', line 20

def implement(env)
  # Ideally we'd let AR do its stuff and then add the extras.
  #
  # But one of the extras is expressions.  AR completely strips out
  # indexes with expressions, so to handle them we need to
  # essentially reissue the original query and then duplicate what
  # AR does to process them.  That being the case we may as well
  # just skip AR's implementation and use ours.
  #
  # We could limit that query to just those indexes that have
  # expressions, but we'd still have our code duplicating the AR
  # code.  Plus, our own query can handle operator classess at the
  # same time, but to add operator_classes to AR's definitions we'd
  # still have to issue additional queries.  Plus, using our own
  # query we have the opportunity to handle tables of the form
  # 'namespace.tablename'
  #
  # So, this replacs the AR implementation

  result = env.connection.query(<<-SQL, 'SCHEMA')
    SELECT distinct i.relname, d.indisunique, d.indkey, pg_get_indexdef(d.indexrelid), t.oid,
            m.amname, pg_get_expr(d.indpred, t.oid) as conditions, pg_get_expr(d.indexprs, t.oid) as expression,
            d.indclass
    FROM pg_class t
    INNER JOIN pg_index d ON t.oid = d.indrelid
    INNER JOIN pg_class i ON d.indexrelid = i.oid
    INNER JOIN pg_am m ON i.relam = m.oid
    WHERE i.relkind = 'i'
      AND d.indisprimary = 'f'
      AND t.relname = '#{table_name_without_namespace(env.table_name)}'
      AND i.relnamespace IN (SELECT oid FROM pg_namespace WHERE nspname = #{namespace_sql(env.table_name)} )
    ORDER BY i.relname
  SQL

  env.index_definitions += result.map do |(index_name, unique, indkey, inddef, oid, using, conditions, expression, indclass)|
    index_keys = indkey.split(" ")
    opclasses = indclass.split(" ")

    rows = env.connection.query(<<-SQL, 'SCHEMA')
      SELECT CAST(a.attnum as VARCHAR), a.attname, t.typname
      FROM pg_attribute a
      INNER JOIN pg_type t ON a.atttypid = t.oid
      WHERE a.attrelid = #{oid}
    SQL
    columns = {}
    types = {}
    rows.each do |num, name, type|
      columns[num] = name
      types[name] = type
    end

    column_names = columns.values_at(*index_keys).compact
    case_sensitive = true

    # extract column names from the expression, for a
    # case-insensitive index.
    # only applies to character, character varying, and text
    if expression
      rexp_lower = %r{\blower\(\(?([^)]+)(\)::text)?\)}
      if expression.match /\A#{rexp_lower}(?:, #{rexp_lower})*\z/i
        case_insensitive_columns = expression.scan(rexp_lower).map(&:first).select{|column| %W[char varchar text].include? types[column]}
        if case_insensitive_columns.any?
          case_sensitive = false
          column_names = index_keys.map { |index_key|
            index_key == '0' ? case_insensitive_columns.shift : columns[index_key]
          }.compact | column_names
        end
      end
    end

    get_opclass_names(env, opclasses)
    operator_classes = Hash[
      index_keys.zip(opclasses).map { |index_key, opclass| [columns[index_key], @opclass_names[opclass]] }
    ]
    operator_classes.delete_if{|k,v| v.nil?}

    # add info on sort order for columns (only desc order is explicitly specified, asc is the default)
    desc_order_columns = inddef.scan(/(\w+) DESC/).flatten
    orders = desc_order_columns.any? ? Hash[column_names.map {|column| [column, desc_order_columns.include?(column) ? :desc : :asc]}] : {}

    ::ActiveRecord::ConnectionAdapters::IndexDefinition.new(env.table_name, column_names,
                                                            :name => index_name,
                                                            :unique => (unique == 't'),
                                                            :orders => orders,
                                                            :where => conditions,
                                                            :case_sensitive => case_sensitive,
                                                            :using => using.downcase == "btree" ? nil : using.to_sym,
                                                            :operator_classes => operator_classes,
                                                            :expression => expression)
  end
end

#namespace_sql(table_name) ⇒ Object 



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# File 'lib/schema_plus_pg_indexes/middleware/postgresql/schema.rb', line 112

def namespace_sql(table_name)
  (table_name.to_s =~ /(.*)[.]/) ?  "'#{$1}'" : "ANY (current_schemas(false))"
end

#table_name_without_namespace(table_name) ⇒ Object 



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# File 'lib/schema_plus_pg_indexes/middleware/postgresql/schema.rb', line 116

def table_name_without_namespace(table_name)
  table_name.to_s.sub /.*[.]/, ''
end