Sorry, was in a rush before. I still don't have time to fix this for
8.0.2, so that's why I rushed out the report. Here is a full description...
> You can drop a NOT NULL on a column, even if that column is part of an
> index that is clustered, where the index does not index NULLs.
First, install tsearch2...
test=# create table test (a tsvector);
CREATE TABLE
test=# create index test_gist_idx on test using gist (a);
CREATE INDEX
test=# \d test Table "public.test" Column | Type | Modifiers
--------+----------+----------- a | tsvector |
Indexes: "test_gist_idx" gist (a)
test=# cluster test_gist_idx on test;
ERROR: cannot cluster when index access method does not handle null values
HINT: You may be able to work around this by marking column "a" NOT NULL.
test=# alter table test alter a set not null;
ALTER TABLE
test=# cluster test_gist_idx on test;
CLUSTER
test=# \d test Table "public.test" Column | Type | Modifiers
--------+----------+----------- a | tsvector | not null
Indexes: "test_gist_idx" gist (a) CLUSTER
test=# alter table test alter a drop not null;
ALTER TABLE
test=# cluster test_gist_idx on test;
ERROR: cannot cluster when index access method does not handle null values
HINT: You may be able to work around this by marking column "a" NOT NULL.
test=# \d test Table "public.test" Column | Type | Modifiers
--------+----------+----------- a | tsvector |
Indexes: "test_gist_idx" gist (a) CLUSTER
Note that index is still 'clustered', but unclusterable.
The correct behaviour IMHO is to prevent dropping NOT NULL on a column
that particpates in such an index. (Index access method that does not
handle nulls)
> Also, I dont think that ALTER TABLE blah CLUSTER ON foo; actually warns
> about clustering a non-null indexing index. However, CLUSTER foo ON
> blah; does.
I was wrong about that...
Chris
