drainer/: Fix when pk is handle and value overflow int64 #573
What problem does this PR solve?
Fix when pk is handle and value overflow int64
before this pr:
note uint64(int64(-1)) = 18446744073709551615
the test added also fix https://internal.pingcap.net/jira/browse/TOOL-1139
What is changed and how it works?
change to uint64 from int64 when the pk column is unsigned