Re: Parser Hook

> Also, I'm not sure that many extensions would really benefit from custom
> utility command, as you can already do pretty much anything you want using
> SQL
> functions. For instance it would be nice for hypopg to be able to support
>
> CREATE HYPOTHETICAL INDEX ...
>
> rather than
>
> SELECT hypopg_create_index('CREATE INDEX...')
>
> But really the only benefit would be autocompletion, which still wouldn't
> be
> possible as psql autocompletion won't be extended. And even if it somehow
> was,
> I wouldn't expect all psql clients to be setup as needed.
>

The extending parser can be interesting for two cases

a) compatibility with other databases

b) experimental supports of some features standard (current or future)

c) some experiments - using

CREATE PIPE xxx(xxx), or CREATE HYPERCUBE xxx (xxx) is more readable more
SQLish (more natural syntax) than

SELECT create_pipe('name', 'a1', 'int', ...) or SELECT ext('CREATE PIPE ...)

Possibility to work with a parser is one main reason for forking postgres.
Lot of interestings projects fail on the cost of maintaining their own fork.

Maybe a good enough possibility is the possibility to inject an own parser
called before Postgres parser. Then it can do a transformation from "CREATE
PIPE ..." to "SELECT extparse("CREATE PIPE()". There can be a switch if
returned content is string for reparsing or already prepared AST.

It can be very interesting feature.

Pavel