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Re: Do we want a hashset type? - Mailing list pgsql-hackers

From	Joel Jacobson
Subject	Re: Do we want a hashset type?
Date	June 27, 2023 23:25:52
Msg-id	b9562b5e-1dd7-4c18-ab97-b1924e213110@app.fastmail.com Whole thread Raw
In response to	Re: Do we want a hashset type? ("Joel Jacobson" <joel@compiler.org>)
List	pgsql-hackers
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On Tue, Jun 27, 2023, at 10:26, Joel Jacobson wrote:
> Attachments:
> * hashset-0.0.1-b7e5614-full.patch
> * hashset-0.0.1-b7e5614-incremental.patch

To help verify that the semantics, I thought it might be helpful to provide
a comprehensive set of examples that tries to cover all different ways of varying
the arguments to the functions.

Please let me know if you find any possible errors or if you think it looks good.

SELECT NULL::int4hashset;
 int4hashset
-------------

(1 row)

SELECT '{}'::int4hashset;
 int4hashset
-------------
 {}
(1 row)

SELECT int4hashset();
 int4hashset
-------------
 {}
(1 row)

SELECT '{NULL}'::int4hashset;
 int4hashset
-------------
 {NULL}
(1 row)

SELECT '{NULL,NULL}'::int4hashset;
 int4hashset
-------------
 {NULL}
(1 row)

SELECT '{1,3,2,NULL,2,NULL,3,1}'::int4hashset;
 int4hashset
--------------
 {2,1,3,NULL}
(1 row)

SELECT hashset_add(NULL, NULL);
 hashset_add
-------------
 {NULL}
(1 row)

SELECT hashset_add(NULL, 1);
 hashset_add
-------------
 {1}
(1 row)

SELECT hashset_add('{}', 1);
 hashset_add
-------------
 {1}
(1 row)

SELECT hashset_add('{NULL}', 1);
 hashset_add
-------------
 {1,NULL}
(1 row)

SELECT hashset_add('{1}', 1);
 hashset_add
-------------
 {1}
(1 row)

SELECT hashset_add('{1}', 2);
 hashset_add
-------------
 {1,2}
(1 row)

SELECT hashset_add('{1}', NULL);
 hashset_add
-------------
 {1,NULL}
(1 row)

SELECT hashset_contains(NULL, NULL);
 hashset_contains
------------------

(1 row)

SELECT hashset_contains('{}', NULL);
 hashset_contains
------------------
 f
(1 row)

SELECT hashset_contains('{NULL}', NULL);
 hashset_contains
------------------

(1 row)

SELECT hashset_contains('{1}', 1);
 hashset_contains
------------------
 t
(1 row)

SELECT hashset_contains('{1,NULL}', 1);
 hashset_contains
------------------
 t
(1 row)

SELECT hashset_contains('{1}', 2);
 hashset_contains
------------------
 f
(1 row)

SELECT hashset_contains('{1,NULL}', 2);
 hashset_contains
------------------

(1 row)

SELECT hashset_to_array(NULL);
 hashset_to_array
------------------

(1 row)

SELECT hashset_to_array('{}');
 hashset_to_array
------------------
 {}
(1 row)

SELECT hashset_to_array('{NULL}');
 hashset_to_array
------------------
 {NULL}
(1 row)

SELECT hashset_to_array('{3,1,NULL,2}');
 hashset_to_array
------------------
 {1,3,2,NULL}
(1 row)

SELECT hashset_to_sorted_array(NULL);
 hashset_to_sorted_array
-------------------------

(1 row)

SELECT hashset_to_sorted_array('{}');
 hashset_to_sorted_array
-------------------------
 {}
(1 row)

SELECT hashset_to_sorted_array('{NULL}');
 hashset_to_sorted_array
-------------------------
 {NULL}
(1 row)

SELECT hashset_to_sorted_array('{3,1,NULL,2}');
 hashset_to_sorted_array
-------------------------
 {1,2,3,NULL}
(1 row)

SELECT hashset_cardinality(NULL);
 hashset_cardinality
---------------------

(1 row)

SELECT hashset_cardinality('{}');
 hashset_cardinality
---------------------
                   0
(1 row)

SELECT hashset_cardinality('{NULL}');
 hashset_cardinality
---------------------
                   1
(1 row)

SELECT hashset_cardinality('{NULL,NULL}');
 hashset_cardinality
---------------------
                   1
(1 row)

SELECT hashset_cardinality('{1}');
 hashset_cardinality
---------------------
                   1
(1 row)

SELECT hashset_cardinality('{1,1}');
 hashset_cardinality
---------------------
                   1
(1 row)

SELECT hashset_cardinality('{1,2}');
 hashset_cardinality
---------------------
                   2
(1 row)

SELECT hashset_cardinality('{1,2,NULL}');
 hashset_cardinality
---------------------
                   3
(1 row)

SELECT hashset_union(NULL, NULL);
 hashset_union
---------------

(1 row)

SELECT hashset_union(NULL, '{}');
 hashset_union
---------------

(1 row)

SELECT hashset_union('{}', NULL);
 hashset_union
---------------

(1 row)

SELECT hashset_union('{}', '{}');
 hashset_union
---------------
 {}
(1 row)

SELECT hashset_union('{}', '{NULL}');
 hashset_union
---------------
 {NULL}
(1 row)

SELECT hashset_union('{NULL}', '{}');
 hashset_union
---------------
 {NULL}
(1 row)

SELECT hashset_union('{NULL}', '{NULL}');
 hashset_union
---------------
 {NULL}
(1 row)

SELECT hashset_union('{}', '{1}');
 hashset_union
---------------
 {1}
(1 row)

SELECT hashset_union('{1}', '{}');
 hashset_union
---------------
 {1}
(1 row)

SELECT hashset_union('{1}', '{1}');
 hashset_union
---------------
 {1}
(1 row)

SELECT hashset_union('{1}', NULL);
 hashset_union
---------------

(1 row)

SELECT hashset_union(NULL, '{1}');
 hashset_union
---------------

(1 row)

SELECT hashset_union('{1}', '{NULL}');
 hashset_union
---------------
 {1,NULL}
(1 row)

SELECT hashset_union('{NULL}', '{1}');
 hashset_union
---------------
 {1,NULL}
(1 row)

SELECT hashset_union('{1}', '{2}');
 hashset_union
---------------
 {1,2}
(1 row)

SELECT hashset_union('{1,2}', '{2,3}');
 hashset_union
---------------
 {3,1,2}
(1 row)

SELECT hashset_intersection(NULL, NULL);
 hashset_intersection
----------------------

(1 row)

SELECT hashset_intersection(NULL, '{}');
 hashset_intersection
----------------------

(1 row)

SELECT hashset_intersection('{}', NULL);
 hashset_intersection
----------------------

(1 row)

SELECT hashset_intersection('{}', '{}');
 hashset_intersection
----------------------
 {}
(1 row)

SELECT hashset_intersection('{}', '{NULL}');
 hashset_intersection
----------------------
 {}
(1 row)

SELECT hashset_intersection('{NULL}', '{}');
 hashset_intersection
----------------------
 {}
(1 row)

SELECT hashset_intersection('{NULL}', '{NULL}');
 hashset_intersection
----------------------
 {NULL}
(1 row)

SELECT hashset_intersection('{}', '{1}');
 hashset_intersection
----------------------
 {}
(1 row)

SELECT hashset_intersection('{1}', '{}');
 hashset_intersection
----------------------
 {}
(1 row)

SELECT hashset_intersection('{1}', '{1}');
 hashset_intersection
----------------------
 {1}
(1 row)

SELECT hashset_intersection('{1}', NULL);
 hashset_intersection
----------------------

(1 row)

SELECT hashset_intersection(NULL, '{1}');
 hashset_intersection
----------------------

(1 row)

SELECT hashset_intersection('{1}', '{NULL}');
 hashset_intersection
----------------------
 {}
(1 row)

SELECT hashset_intersection('{NULL}', '{1}');
 hashset_intersection
----------------------
 {}
(1 row)

SELECT hashset_intersection('{1}', '{2}');
 hashset_intersection
----------------------
 {}
(1 row)

SELECT hashset_intersection('{1,2}', '{2,3}');
 hashset_intersection
----------------------
 {2}
(1 row)

SELECT hashset_difference(NULL, NULL);
 hashset_difference
--------------------

(1 row)

SELECT hashset_difference(NULL, '{}');
 hashset_difference
--------------------

(1 row)

SELECT hashset_difference('{}', NULL);
 hashset_difference
--------------------

(1 row)

SELECT hashset_difference('{}', '{}');
 hashset_difference
--------------------
 {}
(1 row)

SELECT hashset_difference('{}', '{NULL}');
 hashset_difference
--------------------
 {}
(1 row)

SELECT hashset_difference('{NULL}', '{}');
 hashset_difference
--------------------
 {NULL}
(1 row)

SELECT hashset_difference('{NULL}', '{NULL}');
 hashset_difference
--------------------
 {}
(1 row)

SELECT hashset_difference('{}', '{1}');
 hashset_difference
--------------------
 {}
(1 row)

SELECT hashset_difference('{1}', '{}');
 hashset_difference
--------------------
 {1}
(1 row)

SELECT hashset_difference('{1}', '{1}');
 hashset_difference
--------------------
 {}
(1 row)

SELECT hashset_difference('{1}', NULL);
 hashset_difference
--------------------

(1 row)

SELECT hashset_difference(NULL, '{1}');
 hashset_difference
--------------------

(1 row)

SELECT hashset_difference('{1}', '{NULL}');
 hashset_difference
--------------------
 {1}
(1 row)

SELECT hashset_difference('{NULL}', '{1}');
 hashset_difference
--------------------
 {NULL}
(1 row)

SELECT hashset_difference('{1}', '{2}');
 hashset_difference
--------------------
 {1}
(1 row)

SELECT hashset_difference('{1,2}', '{2,3}');
 hashset_difference
--------------------
 {1}
(1 row)

SELECT hashset_symmetric_difference(NULL, NULL);
 hashset_symmetric_difference
------------------------------

(1 row)

SELECT hashset_symmetric_difference(NULL, '{}');
 hashset_symmetric_difference
------------------------------

(1 row)

SELECT hashset_symmetric_difference('{}', NULL);
 hashset_symmetric_difference
------------------------------

(1 row)

SELECT hashset_symmetric_difference('{}', '{}');
 hashset_symmetric_difference
------------------------------
 {}
(1 row)

SELECT hashset_symmetric_difference('{}', '{NULL}');
 hashset_symmetric_difference
------------------------------
 {NULL}
(1 row)

SELECT hashset_symmetric_difference('{NULL}', '{}');
 hashset_symmetric_difference
------------------------------
 {NULL}
(1 row)

SELECT hashset_symmetric_difference('{NULL}', '{NULL}');
 hashset_symmetric_difference
------------------------------
 {}
(1 row)

SELECT hashset_symmetric_difference('{}', '{1}');
 hashset_symmetric_difference
------------------------------
 {1}
(1 row)

SELECT hashset_symmetric_difference('{1}', '{}');
 hashset_symmetric_difference
------------------------------
 {1}
(1 row)

SELECT hashset_symmetric_difference('{1}', '{1}');
 hashset_symmetric_difference
------------------------------
 {}
(1 row)

SELECT hashset_symmetric_difference('{1}', NULL);
 hashset_symmetric_difference
------------------------------

(1 row)

SELECT hashset_symmetric_difference(NULL, '{1}');
 hashset_symmetric_difference
------------------------------

(1 row)

SELECT hashset_symmetric_difference('{1}', '{NULL}');
 hashset_symmetric_difference
------------------------------
 {1,NULL}
(1 row)

SELECT hashset_symmetric_difference('{NULL}', '{1}');
 hashset_symmetric_difference
------------------------------
 {1,NULL}
(1 row)

SELECT hashset_symmetric_difference('{1}', '{2}');
 hashset_symmetric_difference
------------------------------
 {1,2}
(1 row)

SELECT hashset_symmetric_difference('{1,2}', '{2,3}');
 hashset_symmetric_difference
------------------------------
 {1,3}
(1 row)

SELECT hashset_eq(NULL, NULL);
 hashset_eq
------------

(1 row)

SELECT hashset_eq(NULL, '{}');
 hashset_eq
------------

(1 row)

SELECT hashset_eq('{}', NULL);
 hashset_eq
------------

(1 row)

SELECT hashset_eq('{}', '{}');
 hashset_eq
------------
 t
(1 row)

SELECT hashset_eq('{}', '{NULL}');
 hashset_eq
------------
 f
(1 row)

SELECT hashset_eq('{NULL}', '{}');
 hashset_eq
------------
 f
(1 row)

SELECT hashset_eq('{NULL}', '{NULL}');
 hashset_eq
------------
 t
(1 row)

SELECT hashset_eq('{}', '{1}');
 hashset_eq
------------
 f
(1 row)

SELECT hashset_eq('{1}', '{}');
 hashset_eq
------------
 f
(1 row)

SELECT hashset_eq('{1}', '{1}');
 hashset_eq
------------
 t
(1 row)

SELECT hashset_eq('{1}', NULL);
 hashset_eq
------------

(1 row)

SELECT hashset_eq(NULL, '{1}');
 hashset_eq
------------

(1 row)

SELECT hashset_eq('{1}', '{NULL}');
 hashset_eq
------------
 f
(1 row)

SELECT hashset_eq('{NULL}', '{1}');
 hashset_eq
------------
 f
(1 row)

SELECT hashset_eq('{1}', '{2}');
 hashset_eq
------------
 f
(1 row)

SELECT hashset_eq('{1,2}', '{2,3}');
 hashset_eq
------------
 f
(1 row)

SELECT hashset_ne(NULL, NULL);
 hashset_ne
------------

(1 row)

SELECT hashset_ne(NULL, '{}');
 hashset_ne
------------

(1 row)

SELECT hashset_ne('{}', NULL);
 hashset_ne
------------

(1 row)

SELECT hashset_ne('{}', '{}');
 hashset_ne
------------
 f
(1 row)

SELECT hashset_ne('{}', '{NULL}');
 hashset_ne
------------
 t
(1 row)

SELECT hashset_ne('{NULL}', '{}');
 hashset_ne
------------
 t
(1 row)

SELECT hashset_ne('{NULL}', '{NULL}');
 hashset_ne
------------
 f
(1 row)

SELECT hashset_ne('{}', '{1}');
 hashset_ne
------------
 t
(1 row)

SELECT hashset_ne('{1}', '{}');
 hashset_ne
------------
 t
(1 row)

SELECT hashset_ne('{1}', '{1}');
 hashset_ne
------------
 f
(1 row)

SELECT hashset_ne('{1}', NULL);
 hashset_ne
------------

(1 row)

SELECT hashset_ne(NULL, '{1}');
 hashset_ne
------------

(1 row)

SELECT hashset_ne('{1}', '{NULL}');
 hashset_ne
------------
 t
(1 row)

SELECT hashset_ne('{NULL}', '{1}');
 hashset_ne
------------
 t
(1 row)

SELECT hashset_ne('{1}', '{2}');
 hashset_ne
------------
 t
(1 row)

SELECT hashset_ne('{1,2}', '{2,3}');
 hashset_ne
------------
 t
(1 row)

/Joel
pgsql-hackers by date:
From: Peter Geoghegan
Date: 27 June 2023, 22:50:37
Subject: Re: POC, WIP: OR-clause support for indexes
From: Roberto Mello
Date: 28 June 2023, 00:44:28
Subject: Re: PostgreSQL 16 Beta 2 release announcement draft
Re: Do we want a hashset type? - Mailing list pgsql-hackers

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