Re: Support logical replication of DDLs

Hi,

Attaching v25 patch which adds supports for:
CREATE TRANSFORM
DROP TRANSFORM

These are relatively new commands so they're not in the original DDL
deparser patch.
Some tweaking is made in deparse_drop_command in order to make DROP
TRANSFORM deparsing work. This is because the objidentity captured in
currentEventTriggerState->SQLDropList contains the keyword 'on', for
example "for typename on language lang", but the keyword 'on' is not
needed in the current DROP TRANSFORM syntax. So we need to remove the
'on' keyword in objidentity. I'm not sure if this is the best way to
handle it, maybe
we can consider directly modifying what's captured in
currentEventTriggerState->SQLDropList
so we don't have the "on" keyword to begin with?

BTW, my colleague Runqi started a new thread to discuss DDL deparser
testing in [1].
Your feedback is appreciated.

With Regards,
Zheng Li

[1] https://www.postgresql.org/message-id/CAH8n8_jMTunxxtP4L-3tc%3DGNamg%3Dmg1X%3DtgHr9CqqjjzFLwQng%40mail.gmail.com