Re: SQL:2011 application time

From: Peter Eisentraut <peter(at)eisentraut(dot)org>
To: Paul Jungwirth <pj(at)illuminatedcomputing(dot)com>, jian he <jian(dot)universality(at)gmail(dot)com>
Cc: PostgreSQL Hackers <pgsql-hackers(at)lists(dot)postgresql(dot)org>
Subject: Re: SQL:2011 application time
Date: 2023-09-25 21:00:30
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On 25.09.23 21:20, Paul Jungwirth wrote:
> On 9/24/23 21:52, jian he wrote:
>> On Wed, Sep 20, 2023 at 10:50 AM Paul Jungwirth
>> <pj(at)illuminatedcomputing(dot)com> wrote:
>>> On 9/17/23 20:11, jian he wrote:
>>>> small issues so far I found, v14.
>>> Thank you again for the review! v15 is attached.
>> hi. some tiny issues.
> Rebased v16 patches attached.

Looking through the tests in v16-0001:

+-- PK with no columns just WITHOUT OVERLAPS:
+CREATE TABLE temporal_rng (
+ valid_at tsrange,
+ERROR: syntax error at or near "WITHOUT"
+LINE 3: CONSTRAINT temporal_rng_pk PRIMARY KEY (valid_at WITHOUT OV...
+ ^

I think this error is confusing. The SQL standard requires at least one
non-period column in a PK. I don't know why that is or why we should
implement it. But if we want to implement it, maybe we should enforce
that in parse analysis rather than directly in the parser, to be able to
produce a more friendly error message.

+-- PK with a range column/PERIOD that isn't there:
+CREATE TABLE temporal_rng (
+ CONSTRAINT temporal_rng_pk PRIMARY KEY (id, valid_at WITHOUT
+ERROR: range or PERIOD "valid_at" in WITHOUT OVERLAPS does not exist

I think here we should just produce a "column doesn't exist" error
message, the same as if the "id" column was invalid. We don't need to
get into the details of what kind of column it should be. That is done
in the next test

+ERROR: column "valid_at" in WITHOUT OVERLAPS is not a range type

Also, in any case it would be nice to have a location pointer here (for
both cases).

+-- PK with one column plus a range:
+CREATE TABLE temporal_rng (
+ -- Since we can't depend on having btree_gist here,
+ -- use an int4range instead of an int.
+ -- (The rangetypes regression test uses the same trick.)
+ id int4range,
+ valid_at tsrange,
+ CONSTRAINT temporal_rng_pk PRIMARY KEY (id, valid_at WITHOUT

I'm confused why you are using int4range here (and in further tests) for
the scalar (non-range) part of the primary key. Wouldn't a plaint int4
serve here?

+SELECT pg_get_indexdef(conindid, 0, true) FROM pg_constraint WHERE
conname = 'temporal_rng_pk';
+ pg_get_indexdef
+ CREATE UNIQUE INDEX temporal_rng_pk ON temporal_rng USING gist (id,

Shouldn't this somehow show the operator classes for the columns? We
are using different operator classes for the id and valid_at columns,
aren't we?

+-- PK with USING INDEX (not possible):
+CREATE TABLE temporal3 (
+ id int4range,
+ valid_at tsrange
+CREATE INDEX idx_temporal3_uq ON temporal3 USING gist (id, valid_at);
+ALTER TABLE temporal3
+ ADD CONSTRAINT temporal3_pk
+ PRIMARY KEY USING INDEX idx_temporal3_uq;
+ERROR: "idx_temporal3_uq" is not a unique index
+LINE 2: ADD CONSTRAINT temporal3_pk
+ ^
+DETAIL: Cannot create a primary key or unique constraint using such an

Could you also add a test where the index is unique and the whole thing
does work?

Apart from the tests, how about renaming the column
pg_constraint.contemporal to something like to conwithoutoverlaps?

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