Re: Incremental View Maintenance, take 2

This is probably not trivial. 

In function  apply_new_delta_with_count.

 appendStringInfo(&querybuf,
"WITH updt AS (" /* update a tuple if this exists in the view */
"UPDATE %s AS mv SET %s = mv.%s OPERATOR(pg_catalog.+) diff.%s "
"%s " /* SET clauses for aggregates */
"FROM %s AS diff "
"WHERE %s " /* tuple matching condition */
"RETURNING %s" /* returning keys of updated tuples */
") INSERT INTO %s (%s)" /* insert a new tuple if this doesn't existw */
"SELECT %s FROM %s AS diff "
"WHERE NOT EXISTS (SELECT 1 FROM updt AS mv WHERE %s);",

---------------------

") INSERT INTO %s (%s)" /* insert a new tuple if this doesn't existw */
"SELECT %s FROM %s AS diff "

the INSERT INTO line, should have one white space in the end? 

also "existw" should be "exists"