PL Features Matrix

Goal of this page is to document the main features of a Procedural Language, and summarize which features each implemented language provides.

List of Features

• accepts named args
• returns arrays
• returns tables
• has a validator function
• supports triggers
• variadic
  • on TRUNCATE
  • FOR EACH STATEMENT

• Trusted mode (security)
  • Have a need for testers for trusted languages
  • We probably will not accept additional languages in core, but we may get to the point where we stop allowing non-core trusted languages
  • PL/Ruby - stuff you can turn on/off ?

• DO block support (aka inline handlers)
• Composite type support
• Native types
  • ENUMs - passing it too and from a language that does or doesn't support enums
  • how does type mapping work in general?

• SPI interface documentation
  • Cursor support

• Subtransactions
• Support for OUT arguments, how is it bound to the native language

• Sharing data / global hash to allow functions to share data :) (in the same PLs)
• Quoting functions (string escaping)

• AUTOLOAD support (TCL, Perl has it)
  • Standardize where each PL does this (a table?)

Wishlist / Alternative architectural discussions

• Getting functions to have introspection
• Ability to handle internal types: text search parsers, windowing functions, aggregate functions in PLs :), -- how to expose?, extend API in backend to allow this
• Foreign Data Wrappers
• Streaming SRFs (tuple store discussion)
• How to merge PL/PSM without having to duplicate 70% of the PL/pgsql code

• Top memory context vs caching of XYZ somewhere else
  • output of a JIT stashed in memory
  • TODO: hook for a DROP FUNCTION to clean up the cache
  • boilerplate in the PL code ? -->
    • PL handler: pass a pointer to a piece of memory so you can store whatever you want
    • PL handler: also keep track of lifecycle
    • hash table support to stash the compiled version of the function
    • Tim wrote a NULL language: shell of a validator, executor

TODO

• Publish code for PL/NULL - Tim
• Make a list of all the boilerplate code :) - Tim, Selena will send email to -hackers about it
• Set up a 1/2 day meeting at the next pgcon - Josh Berkus (?)
• Set up a Skype session in a few months time to go over progress - Selena (Tim, Alvaro agreed to attend)
• Further discussion of DDL triggers - Jan
• Further discussion of permission system - Steve
• Further discussion of per-statement config parameters for things like timezone - Jan

PL interface improvements

• Can't write INPUT/OUTPUT functions in languages other than C
  • PL handler needs to know that it is now an i/o function, and i just passed a DATUM through (usually get pointers to these)
  • Most PLs wrap all the args in text (but not python for bytea)
  • Peter -- SQL CREATE *something* standard - casts for type between PLs and SQL (?); e.g. hstores in PL/Python - create transforms for [type name]
  • Tim does it with casts for functions
  • email Dec 15 2011 hstores in pl/python
  • http://publib.boulder.ibm.com/infocenter/db2luw/v9r7/index.jsp?topic=/com.ibm.db2.luw.sql.ref.doc/doc/r0003292.html
  • Pass arguments in their native format without going through i/o functions
  • Profiling: a lot of time is spent in the pg i/o functions

Matrix

See PL_Matrix