PostgreSQL primary key length limit

postgresql primary-key varchar
FolksLord picture FolksLord · Dec 27, 2010 · Viewed 9.9k times · Source

What is the limit of the length of primary key column? I'm going to use varchar as primary key. I've found no info, how long it can be, since PostgreSQL does not require to specify varchar limit when used as primary key?

Answer

Peter Eisentraut picture Peter Eisentraut · Dec 27, 2010

The maximum length for a value in a B-tree index, which includes primary keys, is one third of the size of a buffer page, by default floor(8192/3) = 2730 bytes.

Related questions

How to reset postgres' primary key sequence when it falls out of sync?

I ran into the problem that my primary key sequence is not in sync with my table rows. That is, when I insert a new row I get a duplicate key error because the sequence implied in the serial datatype …

Read More
How to add an auto-incrementing primary key to an existing table, in PostgreSQL?

I have a table with existing data. Is there a way to add a primary key without deleting and re-creating the table?

Read More
Reset PostgreSQL primary key to 1

Is there a way to reset the primary key of a PostgreSQL table to start at 1 again on a populated table? Right now it's generating numbers from 1000000 and up. I want it all to reset and start to 1, keeping all …

Read More