Hackers,

I need a constraint that ensures that a text[] column has only unique values -- 
that is, that there is no overlap of values between rows. I thought this was a 
made-to-order for an exclusion constraint. So I tried it:

david=# create table tags (names text[] primary key, exclude using gist (names 
WITH &&));NOTICE:  CREATE TABLE / PRIMARY KEY will create implicit index 
"tags_pkey" for table "tags"
ERROR:  data type text[] has no default operator class for access method "gist"
HINT:  You must specify an operator class for the index or define a default 
operator class for the data type.

Rats! It looks like there is only a gin operator family for arrays, not gist, 
and exclusion constraints support only gist indexes, and I couldn't find an 
operator class, either. Have I missed something, in my (likely) ignorance? Or 
are there perhaps some types to consider modifying to support exclusion 
constraints?

Thanks,

David


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