Support inserting and selecting VECTORs as binary data

[mjonss]

Feature Request

Is your feature request related to a problem? Please describe:

Since VECTOR datatype is implicitly parsed as text as well as converted to text implicitly, there are no way to insert and select VECTOR columns as binary data, causing unnecessary conversion and more network traffic.

Describe the feature you'd like:

Comparing to MySQL it is possible creating a program that inserts an array of 32-bit floats instead of STRING_TO_VECTOR() making it more efficient to insert vectors.

Comparing to MySQL and MariaDB the default format when selecting a VECTOR column is binary, so by default it will return the data as 32-bit float array if VECTOR_TO_STRING() or VEC_ToText() is not used. I cannot find any way to get that from TiDB (it also don't support HEX(vector_column)).

Describe alternatives you've considered:

Teachability, Documentation, Adoption, Migration Strategy:

We should also aim to be compatible with MySQL (and possibly MariaDB) also for VECTOR support.

[mjonss]

MySQL and MariaDB also supports insert Hex values, like INSERT INTO vt (v) VALUES (x'CDCC8C3FCDCC0C4033335340')

[mjonss]

I created a small repository for testing the compatibility between MySQL/MariaDB/TiDB (as well as MySQL with MYVECTOR) https://github.com/mjonss/mysql-vector-compare.