Re: proposal: schema variables

Nico Williams <nico@cryptonector.com>

From: Nico Williams <nico@cryptonector.com>

To: Robert Haas <robertmhaas@gmail.com>

Cc: Pavel Stehule <pavel.stehule@gmail.com>, PostgreSQL Hackers <pgsql-hackers@postgresql.org>

Date: 2017-11-02T15:35:07Z

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

On Thu, Nov 02, 2017 at 06:05:54PM +0530, Robert Haas wrote:
> On Thu, Oct 26, 2017 at 12:51 PM, Pavel Stehule <pavel.stehule@gmail.com> wrote:
> > The variables can be modified by SQL command SET (this is taken from
> > standard, and it natural)
> >
> > SET varname = expression;
> 
> Overloading SET to handle both variables and GUCs seems likely to
> create problems, possibly including security problems.  For example,
> maybe a security-definer function could leave behind variables to
> trick the calling code into failing to set GUCs that it intended to
> set.  Or maybe creating a variable at the wrong time will just break
> things randomly.

That's already true of GUCs, since there are no access controls on
set_config()/current_setting().

Presumably "schema variables" would really just be GUC-like and not at
all like lexically scoped variables.  And also subject to access
controls, thus an overall improvement on set_config()/current_setting().

With access controls, GUCs could become schema variables, and settings
from postgresql.conf could move into the database itself (which I think
would be nice).

Nico
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