Re: ALTER Table and CLUSTER does adding a new column rewrite clustered? (8.4.3)

Scott Carey wrote:
> v. 8.4.3
>
> I have a table that has several indexes, one of which the table is
> clustered on. If I do an ALTER TABLE Foo ADD COLUMN bar integer not
> null default -1;
>
> It re-writes the whole table.

All good questions:

> * Does it adhere to the CLUSTER property of the table and write the new
> version clustered?

The new table is the exact same heap ordering as the old table; it does
not refresh the clustering if the table has become unclustered.

> * Does it properly write it with the FILLFACTOR setting?

Yes, inserts are used to populate the new table, and inserts honor
FILLFACTOR.

> * Are all the indexes re-created too, or are they bloated and need a REINDEX?

They are recreated.

> http://www.postgresql.org/docs/8.4/static/sql-altertable.html
> does not seem to answer the above, it mentions the conditions that
> cause a rewrite but does not say what the state is after the rewrite
> with respect to CLUSTER, FILLFACTOR, and index bloat.

I have added a documentation patch to mention the indexes are rebuilt;
applied patch attached.

The gory details can be found in src/backend/commands/tablecmds.c.

--
Bruce Momjian <bruce(at)momjian(dot)us> http://momjian.us
EnterpriseDB http://enterprisedb.com

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