docs: function (tableName, index) {
              var indexName = this.__quoteIdentifier(index.name || this.__defaultIndexName(tableName,
                  index.columns)), t = index.type, using = "";
              var indexType = "";
              if (t === "fullText") {
                  indexType = "FULLTEXT ";
              } else if (t === "spatial") {
                  indexType = "SPATIAL ";
              } else {
                  indexType = index.unique ? "UNIQUE " : "";
                  using = t ? " USING " + t : "";
              }
              return format("CREATE %sINDEX %s%s ON %s %s", indexType, indexName, using,
                  this.__quoteSchemaTable(tableName), this.literal(index.columns.map(function (c) {
                      return isString(c) ? sql.identifier(c) : c;
                  })));
          }