Re: 回复：how to create index concurrently on partitioned table

On Thu, Sep 24, 2020 at 05:11:03PM +0900, Michael Paquier wrote:
> start. So, the goal of the patch, as I would define it, is to give a
> way to CLUSTER to work on a partitioned table using a given
> partitioned index. Hence, we would perform CLUSTER automatically from
> the top-most parent for any partitions that have an index on the same
> partition tree as the partitioned index defined in USING, switching
> indisclustered automatically depending on the index used.

I think that's right, except there's no need to look for a compatible
partitioned index: we just use the child index.

Also, if a partitioned index is clustered, when we clear indisclustered for
other indexes, should we also propogate that to their parent indexes, if any ?

> From what I can see, attempting to use a CLUSTER on a top-most
> partitioned table fails to work on child tables,

Oops - it looks like this patch never worked right, due to the RECHECK on
indisclustered. I think maybe I returned to the CIC patch and never finishing
with cluster.

> It would be good also to check if
> we have a partition index tree that maps partially with a partition
> table tree (aka no all table partitions have a partition index), where
> these don't get clustered because there is no index to work on.

This should not happen, since a incomplete partitioned index is "invalid".

> Isn't NoLock unsafe here, even knowing that an exclusive lock is taken on
> the parent? It seems to me that at least schema changes should be
> prevented with a ShareLock in the first transaction building the list
> of elements to cluster.

Thanks for noticing. I chose ShareUpdateExclusiveLock since it's
set-exclusive.

--
Justin