Re: proposal: schema variables

Pavel Stehule <pavel.stehule@gmail.com>

From: Pavel Stehule <pavel.stehule@gmail.com>

To: Nico Williams <nico@cryptonector.com>

Cc: PostgreSQL Hackers <pgsql-hackers@postgresql.org>

Date: 2017-10-27T05:08:43Z

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 →

Move WAL sequence code into its own file
- a87987cafca6 19 (unreleased) cited
Add ExplainState argument to pg_plan_query() and planner().
- c83ac02ec730 19 (unreleased) cited
Don't include access/htup_details.h in executor/tuptable.h
- 1a8b5b11e48a 19 (unreleased) cited
Refactor to avoid code duplication in transformPLAssignStmt.
- b0fb2c6aa5a4 19 (unreleased) cited
Avoid including commands/dbcommands.h in so many places
- 325fc0ab14d1 19 (unreleased) cited
Restrict psql meta-commands in plain-text dumps.
- 71ea0d679543 19 (unreleased) cited
Split func.sgml into more manageable pieces
- 4e23c9ef65ac 19 (unreleased) cited
Fix squashing algorithm for query texts
- 0f65f3eec478 18.0 cited
EXPLAIN: Always use two fractional digits for row counts.
- 95dbd827f2ed 18.0 cited
Preliminary refactoring of plpgsql expression construction.
- a654af21ae52 18.0 cited
plpgsql: pure parser and reentrant scanner
- 7b27f5fd36cb 18.0 cited
Add some sanity checks in executor for query ID reporting
- 24f520594809 18.0 cited
Fix misleading error message context
- 4af123ad45bd 18.0 cited
Add macros for looping through a List without a ListCell.
- 14dd0f27d7cd 17.0 cited

Hi

2017-10-27 0:07 GMT+02:00 Nico Williams <nico@cryptonector.com>:

> On Thu, Oct 26, 2017 at 09:21:24AM +0200, Pavel Stehule wrote:
> > Comments, notes?
>
> I like it.
>
> I would further like to move all of postgresql.conf into the database,
> as much as possible, as well as pg_ident.conf and pg_hba.conf.
>
> Variables like current_user have a sort of nesting context
> functionality: calling a SECURITY DEFINER function "pushes" a new value
> onto current_user, then when the function returns the new value of
> current_user is "popped" and the previous value restored.
>

My proposal doesn't expecting with nesting, because there is only one scope
- schema / session - but I don't think so it is necessary

current_user is a function - it is based on parser magic in Postgres. The
origin from Oracle uses the feature of ADA language. When function has no
parameters then parenthesis are optional. So current_user, current_time are
functions current_user(), current_time().

> It might be nice to be able to generalize this.
>
> Questions that then arise:
>
>  - can one see up the stack?
>  - are there permissions issues with seeing up the stack?
>

these variables are pined to schema - so there is not any relation to
stack. It is like global variables.

Theoretically we can introduce "functional" variables, where the value is
based on immediate evaluation of expression. It can be very similar to
current current_user.

>
>
> I recently posted proposing a feature such that SECURITY DEFINER
> functions could observe the _caller_'s current_user.
>

your use case is good example - this proposed feature doesn't depend on
stack, depends on security context (security context stack) what is super
set of call stack

Regards

Pavel

> Nico
> --
>