Horton

Re: proposal: schema variables

Pavel Stehule <pavel.stehule@gmail.com>

View thread
From: Pavel Stehule <pavel.stehule@gmail.com>
To: Dmitry Dolgov <9erthalion6@gmail.com>
Cc: Laurenz Albe <laurenz.albe@cybertec.at>, Erik Rijkers <er@xs4all.nl>, Michael Paquier <michael@paquier.xyz>, Amit Kapila <amit.kapila16@gmail.com>, DUVAL REMI <REMI.DUVAL@cheops.fr>, PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>
Date: 2024-11-10T17:51:40Z
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.

ne 10. 11. 2024 v 17:19 odesílatel Pavel Stehule <pavel.stehule@gmail.com>
napsal:

>
>
> ne 10. 11. 2024 v 16:24 odesílatel Dmitry Dolgov <9erthalion6@gmail.com>
> napsal:
>
>> Hi folks,
>>
>> Thanks for continuing this work. As a side note, I would like to mention
>> how strange the situation in this CF item is. If I understand correctly,
>> there are two hackers threads discussing the same patch, with recent
>> patches posted in both of them. This is obviously confusing, e.g. the
>> main concern from another thread, about names clashing, wasn't even
>> mentioned in this one. Is it possible to reconcile development in one
>> thread?
>>
>
> This is probably my error. I don't try to organize threads, just I'll try
> to reply in the thread where I got a question.
>

I thought a lot of time about better solutions for identifier collisions
and I really don't think so there is some consistent user friendly syntax.
Personally I think there is an easy already implemented solution -
convention - just use a dedicated schema for variables and this schema
should not be in the search path. Or use secondary convention - like using
prefix "__" for session variables. Common convention is using "_" for
PLpgSQL variables. I searched how this issue is solved in other databases,
or in standard, and I found nothing special. The Oracle and SQL/PSM has a
concept of visibility - the variables are not visible outside packages or
modules, but Postgres has nothing similar. It can be emulated by a
dedicated schema without inserting a search path, but it is less strong.

I think we can introduce an alternative syntax, that will not be user
friendly or readable friendly, but it can be without collisions - or can
decrease possible risks.

It is nothing new - SQL does it with old, "new" syntax of inner joins, or
in Postgres we can

where salary < 40000

or

where pg_catalog.int4lt(salary, 40000);


or some like we use for operators OPERATOR(*schema*.*operatorname*)

So introducing VARIABLE(schema.variablename) syntax as an alternative
syntax for accessing variables I really like. I strongly prefer to use this
as only alternative (secondary) syntax, because I don't think it is
friendly syntax or writing friendly, but it is safe, and I can imagine
tools that can replace generic syntax to this special, or that detects
generic syntax and shows some warning. Then users can choose what they
prefer. Two syntaxes - generic and special can be good enough for all - and
this can be perfectly consistent with current Postgres.

Regards

Pavel


> Regards
>
> Pavel
>
>