To: pgsql-hackers@postgresql.org
From: Arcadiy Ivanov <arcadiy@gmail.com>
Subject: Parser extensions (maybe for 10?)
Message-ID: <570C7B5A.9070309@gmail.com>
Date: Tue, 12 Apr 2016 00:36:42 -0400
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I thought I'd float this idea and see if this gets any traction. Please 
forgive my ignorance if this has been discussed already.

Currently the parser and lexer are fully fixed at compile-time and not 
amenable to the extensions - extensions are only capable of introducing 
functions etc.

There is, however, an advantage to being able if not add or alter 
complete statements (which would be nice), but to at least augment 
portions of syntax for existing ones in some places.

For example PGXL adds the following to CREATE TABLE statement:

[
   DISTRIBUTE BY { REPLICATION | ROUNDROBIN | { [HASH | MODULO ] ( 
column_name ) } } |
   DISTRIBUTED { { BY ( column_name ) } | { RANDOMLY } |
   DISTSTYLE { EVEN | KEY | ALL } DISTKEY ( column_name )
]
[ TO { GROUP groupname | NODE ( nodename [, ... ] ) } ]

Compare:

http://www.postgresql.org/docs/9.5/static/sql-createtable.html
http://files.postgres-xl.org/documentation/sql-createtable.html

Is there any interest and/or tips to allow a pluggable parser or at 
least allow some syntactical pluggability by extensions?
I think this may allow some projects to move towards becoming an 
extension as opposed to forking the project entirely.

Cheers,

-- 
Arcadiy Ivanov
arcadiy@gmail.com | @arcivanov | https://ivanov.biz
https://github.com/arcivanov


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    <font face=3D"Verdana">I thought I'd float this idea and see if this
      gets any traction. Please forgive my ignorance if this has been
      discussed already.<br>
      <br>
      Currently the parser and lexer are fully fixed at compile-time and
      not amenable to the extensions - extensions are only capable of
      introducing functions etc. <br>
      <br>
      There is, however, an advantage to being able if not add or alter
      complete statements (which would be nice), but to at least augment
      portions of syntax for existing ones in some places. <br>
      <br>
      For example PGXL adds the following to CREATE TABLE statement:<br>
      <br>
      [ <br>
      =C2=A0 DISTRIBUTE BY { REPLICATION | ROUNDROBIN | { [HASH | MODULO =
] (
      column_name ) } } |<br>
      =C2=A0 DISTRIBUTED { { BY ( column_name ) } | { RANDOMLY } |<br>
      =C2=A0 DISTSTYLE { EVEN | KEY | ALL } DISTKEY ( column_name )<br>
      ]<br>
      [ TO { GROUP groupname | NODE ( nodename [, ... ] ) } ]<br>
      <br>
      Compare:<br>
      <br>
      <a class=3D"moz-txt-link-freetext" href=3D"http://www.postgresql.or=
g/docs/9.5/static/sql-createtable.html">http://www.postgresql.org/docs/9.=
5/static/sql-createtable.html</a><br>
      <a class=3D"moz-txt-link-freetext" href=3D"http://files.postgres-xl=
=2Eorg/documentation/sql-createtable.html">http://files.postgres-xl.org/d=
ocumentation/sql-createtable.html</a><br>
      <br>
      Is there any interest and/or tips to allow a pluggable parser or
      at least allow some syntactical pluggability by extensions? <br>
      I think this may allow some projects to move towards becoming an
      extension as opposed to forking the project entirely.<br>
      <br>
      Cheers,<br>
    </font>
    <pre class=3D"moz-signature" cols=3D"72">--=20
Arcadiy Ivanov
<a class=3D"moz-txt-link-abbreviated" href=3D"mailto:arcadiy@gmail.com">a=
rcadiy@gmail.com</a> | @arcivanov | <a class=3D"moz-txt-link-freetext" hr=
ef=3D"https://ivanov.biz">https://ivanov.biz</a>
<a class=3D"moz-txt-link-freetext" href=3D"https://github.com/arcivanov">=
https://github.com/arcivanov</a>
</pre>
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