[sqlite] Strange performance problem

[Michael Gross]

Hello
I use sqlite 3.2.2. I have a strange performance problem. I am able to 
solve the problem by a slight change in the query but I want to ask if 
somebody can explain this behavior to me:

I have two tables:
  CREATE TABLE t1 (id VARCHAR(40) NOT NULL PRIMARY KEY, deleted BIT);
  CREATE TABLE t2 (id VARCHAR(40) NOT NULL PRIMARY KEY, t1id 
VARCHAR(40), deleted BIT);
  CREATE INDEX idx_t1_deleted ON t1 (deleted);
  CREATE INDEX idx_t2_deleted ON t2 (deleted);
  CREATE INDEX idx_t2_t1id ON t2 (t1id);

When I now insert 2500 times (%d is the incrementing variable):
  INSERT INTO t1 (id, deleted) VALUES ('%d', 0);
  INSERT INTO t2 (id, t1id, deleted) VALUES ('%d', '%d', 0);
  INSERT INTO t2 (id, t1id, deleted) VALUES ('xxx%d', '%d', 0);

The the following query takes about 1 minute:
  SELECT COUNT(*) FROM t2 LEFT JOIN t1 ON t1.id=t2.id WHERE t1.deleted=0

whereas the following quere takes "no" time:
  SELECT COUNT(*) FROM t2 LEFT JOIN t1 ON t1.id=t2.id WHERE t1.deleted<>1


thx
  Michael