RowExistenceExpectation indicates the row existence conditions.
Valid values:
IGNORE: Row existence check is not performed.
EXPECT_EXIST: The row is expected to exist.
EXPECT_NOT_EXIST: The row is not expected to exist.
enum RowExistenceExpectation {
IGNORE = 0;
EXPECT_EXIST = 1;
EXPECT_NOT_EXIST = 2;
}