No constraint and index names

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1

It appears that the constraint name reported under INFORMATION_SCHEMA.TABLE_CONSTRAINTS.CONSTRAINT_NAME is always ‘PRIMARY’ for every primary key constraint, regardless of what name was specified in the CREATE TABLE DDL. The same goes for the corresponding index reported in INFORMATION_SCHEMA.STATISTICS.INDEX_NAME.

Note that for unique constraints and foreign key constraints this is not the case.

I was also a bit surprised that both for reference and sharded tables every primary key index always appears twice in INFORMATION_SCHEMA.STATISTICS. Once with INDEX_TYPE ‘BTREE’ and once with ‘SHARD’. But this is maybe to be expected.

2

Can you give an example of the syntax you used to create the table with the named primary key constraint?

3

I assume like this?

create table s(a int, constraint foobar primary key(a));

4

Yes, like that. But I have noticed that MySQL has the same behavior here (unlike many other RDBMS implementations, however). So from that standpoint it can be considered consistent.