Support HSTORE

[tblundy]

Currently reading from a postgres database that has data in hstore format, I get
PanicException: not implemented: hstore

Hstore is a key-value format, similar to jsonb. https://www.postgresql.org/docs/14/hstore.html
Supporting it could be a worthwhile addition. It could be parsed into a dictionary or passed through as a string.

[wangxiaoying]

Hi @tblundy , thanks for the suggestion! We will add it to our plan for next release (after 0.2.2).

[wangxiaoying]

Hi, we have add the support for HSTORE (convert to string) in 0.2.3 release. However since the underlying's driver does not support this type in copy_out, we can only support this in the cursor protocol. For binary and csv protocol, a workaround is to convert the HSTORE column to string directly in the sql query.