On Fri, 2023-03-31 at 10:35 -0700, Siddharth Jain wrote:
> Is following correct?
> 
> when a PK is created on (X,Y) on the parent table what happens internally is 
> that the
> command is run individually on each of the child tables. nothing more. 
> nothing less.

If you are talking about inheritance, no.  Creating a constraint on the parent 
table
has no effect on a child table.

If you are talking about partitioning: If you create a primary key on the 
partitioned
table, that will be implemented by a partitioned index.  That partitioned index 
consists
of a unique index for each partition.  So I guess that is more or less what you 
mean.

There are some differences between a primary key on the partitioned table and a 
unique
index on each partition:
- the primary key is a constraint, so it can be the target of a foreign key
- the primary key will force a unique index on each new partition
- the primary key keeps you from dropping the unique index on the partitions

Yours,
Laurenz Albe


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