Split api feature

[wyhaya]

This PR split the "server" into the api feature, which can significantly reduce the compilation time for those who just want to use the messages to write a Postgres client.

# Consistent with before, there are no breaking changes
pgwire = "..."

# Only messages
# 120+ crates -> 14 crates
pgwire = { version = "...", default-features = false }

Two unused crates have been deleted.

log = "0.4"
time = "0.3"

Export FORMAT_CODE

This helps the client determine the value format

- pub(crate) const FORMAT_CODE_TEXT: i16 = 0;
+ pub const FORMAT_CODE_TEXT: i16 = 0;

[wyhaya]

pub type Oid = u32;

Oid is just an alias for u32, to avoid introducing postgres_types, we restore it here.

[sunng87]

LGTM. This is great addition to keep the library compact. I will be adding more feature gates to various authentication methods too.

I'm curious how you are using this library in your application, for message format only?

[wyhaya]

I'm curious how you are using this library in your application, for message format only?

My application need to run simple query, but also need to obtain columns/rows(text format) or affected rows (I don't know whether to call execute or query.).
It seems that neither tokio-postgres nor sqlx can meet the demands, so I decided to start writing a pg client from scratch, messages completely meets my needs.

Thank you very much for writing pgwire!

[sunng87]

That's great to hear. I think there can be some use-case on client side and it becomes true.

I will merge this and rename the api feature to server-api in case that you may want to upstream some of your client implementation, as client-api