That makes perfect sense, now that you have explained it. I just didn't pick up on that from the text as written.
-- D. Richard Hipp d...@sqlite.org On Wednesday, October 16th, 2024 at 9:22 AM, Alvaro Herrera <alvhe...@alvh.no-ip.org> wrote: > Hello, > > On 2024-Oct-15, PG Doc comments form wrote: > > > The documentation does not say what happens if you do "CLUSTER tablename" > > and omit the USING clause, which is shown as optional in the BNF, if I'm > > reading it right. Does CLUSTER use the PRIMARY KEY in that case? What if > > no PRIMARY KEY is specified? > > > The table is clustered on the index that was previously selected as the > cluster index (either by running "CLUSTER table ON idx" or by doing > ALTER TABLE tab CLUSTER ON idx"). If no index is selected, an error is > thrown. > > The docs explain it this way: > > When a table is clustered, PostgreSQL remembers which index it was clustered > by. The form CLUSTER table_name reclusters the table using the same index as > before. You can also use the CLUSTER or SET WITHOUT CLUSTER forms of ALTER > TABLE to set the index to be used for future cluster operations, or to clear > any previous setting. > > I'm not sure if we need to make this clearer. It's perfectly clear to > me, but then I already knew what I wanted to read ... > > -- > Álvaro Herrera Breisgau, Deutschland — https://www.EnterpriseDB.com/ > "After a quick R of TFM, all I can say is HOLY CR** THAT IS COOL! PostgreSQL > was > amazing when I first started using it at 7.2, and I'm continually astounded by > learning new features and techniques made available by the continuing work of > the development team." > Berend Tober, > http://archives.postgresql.org/pgsql-hackers/2007-08/msg01009.php
