I think Teodor's solution is wrong as it stands, because if the subquery
finds matches for mapcfg and maptokentype, but none of those rows
produce a non-null ts_lexize result, it will instead emit one row with a
null result, which is not what should happen.
But concatenation with NULL will have result NULL, so "Lexized token" column
will have NULL as supposed.
--
Teodor Sigaev E-mail: [EMAIL PROTECTED]
WWW: http://www.sigaev.ru/
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TIP 9: In versions below 8.0, the planner will ignore your desire to
choose an index scan if your joining column's datatypes do not
match