I got several suggestions to include ordering operator for tsvector to aim
grouping, union and except etc.
I wrote silly comparing function (byte to byte with some optimizations), but I
wondered that for using operator < in order clause its need to declate B-tree
opclass for type:
regression=# select a from test_tsvector order by a;
ERROR: could not identify an ordering operator for type tsvector
HINT: Use an explicit ordering operator or modify the query.
I see in
backend/utils/cache/typcache.c near line 169:
if ((flags & TYPECACHE_LT_OPR) && typentry->lt_opr == InvalidOid) { if
(typentry->btree_opc!= InvalidOid) typentry->lt_opr =
get_opclass_member(typentry->btree_opc,InvalidOid, BTLessStrategyNumber); }
So, I must declare b-tree opclass for tsvector. Why?
My supposition is to guarantee that operator < is really 'less-than' one. Is it?
--
Teodor Sigaev E-mail: teodor@sigaev.ru