id	summary	reporter	owner	description	type	status	component	version	severity	resolution	keywords	cc	stage	has_patch	needs_docs	needs_tests	needs_better_patch	easy	ui_ux
26684	Example for Full-Text Search Index doesn't work	Christophe Pettus	nobody	"The example given for creating an index on a to_tsvector() call doesn't actually work, since to_tsvector() is not immutable (the results of it can change with changes to the underlying dictionaries it is ruled it is built on).

{{{
xof=# create table t (z text);
CREATE TABLE
xof=# create index on t(to_tsvector(z));
ERROR:  functions in index expression must be marked IMMUTABLE
}}}

(As a note, indexes on `tsvector`s should be GIN indexes rather than B-tree.)

For documentation purposes, I'd suggest pointing the reader to the PostgreSQL documentation that describes how to handle this situation."	Cleanup/optimization	new	Documentation	1.10	Release blocker				Unreviewed	0	0	0	0	0	0