Horton

Re: [HACKERS] proposal: schema variables

Pavel Stehule <pavel.stehule@gmail.com>

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From: Pavel Stehule <pavel.stehule@gmail.com>
To: Pavel Golub <pavel@gf.microolap.com>
Cc: PostgreSQL Hackers <pgsql-hackers@postgresql.org>
Date: 2018-02-02T22:06:44Z
Lists: pgsql-hackers, pgsql-performance

Commits

Same data as JSON: GET /api/v1/messages/:b64id/commits the thread's linked commits as JSON, with link sources. API reference →

  1. Move WAL sequence code into its own file

  2. Add ExplainState argument to pg_plan_query() and planner().

  3. Don't include access/htup_details.h in executor/tuptable.h

  4. Refactor to avoid code duplication in transformPLAssignStmt.

  5. Avoid including commands/dbcommands.h in so many places

  6. Restrict psql meta-commands in plain-text dumps.

  7. Split func.sgml into more manageable pieces

  8. Fix squashing algorithm for query texts

  9. EXPLAIN: Always use two fractional digits for row counts.

  10. Preliminary refactoring of plpgsql expression construction.

  11. plpgsql: pure parser and reentrant scanner

  12. Add some sanity checks in executor for query ID reporting

  13. Fix misleading error message context

  14. Add macros for looping through a List without a ListCell.

Attachments

Hi

I wrote proof concept of schema variables. The patch is not nice, but the
functionality is almost complete (for scalars only) and can be good enough
for playing with this concept.

I recap a goals (the order is random):

1. feature like PL/SQL package variables (with similar content life cycle)
2. available from any PL used by PostgreSQL, data can be shared between
different PL
3. possibility to store short life data in fast secured storage
4. possibility to pass parameters and results to/from anonymous blocks
5. session variables with possibility to process static code check
6. multiple API available from different environments - SQL commands, SQL
functions, internal functions
7. data are stored in binary form

Example:

CREATE VARIABLE public.foo AS integer;

LET foo = 10 + 20;

DO $$
declare x int = random() * 1000;
BEGIN
  RAISE NOTICE '%', foo;
  LET foo = x + 100;
END;
$$;

SELECT public.foo + 10;
SELECT * FROM data WHERE col = foo;

All implemented features are described by regress tests

Interesting note - it is running without any modification of plpgsql code.

Regards

Pavel