Re: attach partition to parent table with default partition accessexclusive

On Wed, 2023-04-12 at 03:03 +0000, James Pang (chaolpan) wrote:
> We have a table    wbxdata (xxxx…)  partition by range(starttime) , and have a
> default partition, now we want to add a new partition and move the data from
> default partition to new added partition.
>  
> Begin;
>   Alter table only  wbxdata … detach partition  wbxdata_pdefault;          ---from here, accessexclusive lock on wbxdata_pdefault default partition, and it block all query on parent table wbxdata.
>  Insert into wbxdata_p2305 select * from wbxdata_pdefault where starttime >= ‘2023-05-01 00:00:00’::date and starttime < ‘2023-06-01 00:00:00’;
> Delete from wbxdata_pdefault where starttime >= ‘2023-05-01 00:00:00’::date and starttime < ‘2023-06-01 00:00:00’;
> Alter table only wbxdata attach partition wbxdata_p2305 for values from ‘‘2023-05-01 00:00:00’ TO  ‘2023-06-01 00:00:00’;
> Alter table attach default partition;
> End;
> Is it expected to see all query even select on  parent table  wbxdata got blocked ,
> when  detach default partition and attach default partition ?
> Postgresql 14.7 version.

Yes, that is expected.

I recommend not to use a default partition if you want to attach more partitions later.

Yours,
Laurenz Albe