indexes

# File activerecord/lib/active_record/connection_adapters/sqlite3/schema_statements.rb, line 8
        def indexes(table_name)
          exec_query("PRAGMA index_list(#{quote_table_name(table_name)})", "SCHEMA").map do |row|
            # Indexes SQLite creates implicitly for internal use start with "sqlite_".
            # See https://www.sqlite.org/fileformat2.html#intschema
            next if row["name"].starts_with?("sqlite_")

            index_sql = query_value(<<~SQL, "SCHEMA")
              SELECT sql
              FROM sqlite_master
              WHERE name = #{quote(row['name'])} AND type = 'index'
              UNION ALL
              SELECT sql
              FROM sqlite_temp_master
              WHERE name = #{quote(row['name'])} AND type = 'index'
            SQL

            /\bON\b\s*"?(\w+?)"?\s*\((?<expressions>.+?)\)(?:\s*WHERE\b\s*(?<where>.+))?\z/ =~ index_sql

            columns = exec_query("PRAGMA index_info(#{quote(row['name'])})", "SCHEMA").map do |col|
              col["name"]
            end

            orders = {}

            if columns.any?(&:nil?) # index created with an expression
              columns = expressions
            else
              # Add info on sort order for columns (only desc order is explicitly specified,
              # asc is the default)
              if index_sql # index_sql can be null in case of primary key indexes
                index_sql.scan(/"(\w+)" DESC/).flatten.each { |order_column|
                  orders[order_column] = :desc
                }
              end
            end

            IndexDefinition.new(
              table_name,
              row["name"],
              row["unique"] != 0,
              columns,
              where: where,
              orders: orders
            )
          end.compact
        end