Add codec for Postgres enumerated types

[My-]

Feature Request

Looks like enums are not supported.

Is your feature request related to a problem? Please describe

Maybe I missing something, or doing something wrong but I can't make Postgres enum type work (query with SELECT, INSERT).

Describe the solution you'd like

Possibility to map directly to Java enum type to Postgres enum.

Describe alternatives you've considered

An alternative could be to get enum value as a string.

Teachability, Documentation, Adoption, Migration Strategy

[mp911de]

We decided to not support Java native enums within the driver as enums are a user-space feature regarding their mapping possibilities (string name, ordinal, Postgres type). You can register your own codec if you wish to do so with your specific mapping rules.

[mp911de]

Reopening this issue. The assumption back then was to make enums work with either the VARCHAR or a numeric codec and that's what my previous comment was about.

We can make Postgres enumerated types work by providing a EnumCodec that takes an OID and the Java enum type so we can map enumerated values in both types. From a particular Java type we can derive the Postgres type OID. While reading, we have a reference to a Java enum and can materialize a value.