valid data length for mysql timestamp binary encoding

[MichaelScofield]

In decode.rs:

https://github.com/datafuselabs/opensrv/blob/68aa6a05c7d31b292592d73fa87d994bdde36042/mysql/src/value/decode.rs#L236-L239

The code asserts that v must have length of either 7 or 11.

However, it seems that 0 and 4 are also valid:

from https://mariadb.com/kb/en/resultset-row/#timestamp-binary-encoding

Any specific considerations why this assertion only makes 7 and 11 valid here?

[BohuTANG]

cc @PsiACE for a check.

[PsiACE]

The main reason is that, initially, only the encoding and decoding of data conforming to chrono::NaiveDate were considered. This was basically inherited from msql-srv. I think we need to carefully consider this case and point out why there are parts that are not fully compatible with the mysql protocol.

Later, I will conduct some tests to ensure that it does not disrupt existing behaviors.

Thank you very much for your Issue and PR.

[MichaelScofield]

ping @BohuTANG @PsiACE PTAL