SELECT t1.blah
  FROM t1 LEFT OUTER JOIN t2 ON (t1.blah = t2.blah)
 WHERE t1.blah IS NOT NULL
   AND t2.blah IS NULL
[download]

It's the correct way to rewrite the NOT EXISTS (about 100x faster in my tests) and is faster than the MINUS because it doesn't have to pull both result sets into memory, then do an expensive ARRAYCOMPARE on them.

SQLite doesn't do the full outer join thing, so you have to fake it with two left outer joins :

-- in table2 but not in table1:
SELECT r.id
FROM table2 AS r
LEFT JOIN table1 AS l
  ON r.id = l.id
WHERE
       r.system = ?
   and l.id IS NULL
   and r.id IS NOT NULL

-- in table1 but not in table2:
SELECT l.id
FROM table2 AS l
LEFT JOIN table1 AS r
  ON l.id = r.id
WHERE
       l.system = ?
   and l.id IS NOT NULL
   and r.id IS NULL
SQL
[download]

But other than that, SQLite is up to the task, as it includes a nice bulk import statement (SQLite 2.x) and a bulk loader program (SQLite 3.x).

Update: Added the "full" to "full outer join", as a "left (outer) join" is an outer join too, but one which SQLite does...

Umm ... Corion? That is an outer join. SQLite just doesn't require the OUTER keyword. :-)

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