Re: fix empty array expression in get_qual_for_list()

Here is an example:

create table t1 ( a int) partition by list (a);
create table t11 partition of t1 for values in (null);

*Current constraints:*
postgres=# \d+ t11;
Table "public.t11"
Column | Type | Collation | Nullable | Default | Storage | Stats target
| Description
--------+---------+-----------+----------+---------+---------+--------------+-------------
a | integer | | | | plain |
|
Partition of: t1 FOR VALUES IN (NULL)
Partition constraint: ((a IS NULL) OR (a = ANY (ARRAY[]::integer[])))

*Constraints after fix:*
postgres=# \d+ t11;
Table "public.t11"
Column | Type | Collation | Nullable | Default | Storage | Stats target
| Description
--------+---------+-----------+----------+---------+---------+--------------+-------------
a | integer | | | | plain |
|
Partition of: t1 FOR VALUES IN (NULL)
Partition constraint: (a IS NULL)

Regards,
Jeevan Ladhe

On Mon, Jun 26, 2017 at 4:53 PM, Jeevan Ladhe <jeevan(dot)ladhe(at)enterprisedb(dot)com
> wrote:

> Hi,
>
> In case of list partitioned table:
> 1. If there is a partition accepting only null values and nothing else,
> then
> currently the partition constraints for such a partition are constructed as
> "((a IS NULL) OR (a = ANY (ARRAY[]::integer[])))".
> I think there it is better to avoid constructing an empty array to avoid
> executing ANY expression.
>
> 2.Also, we are constructing an expression using index 0 of arrays in
> PartitionKey since currently we have only one column for list partition in
> key,
> added an assert for this.
>
> PFA.
>
> Regards,
> Jeevan Ladhe
>