DROP DATABASE IF EXISTS bug17164;

CREATE DATABASE bug17164;
USE bug17164;

DROP TABLE IF EXISTS t2;
CREATE TABLE t2 (
  id int(11) NOT NULL,
  name varchar(20),
  PRIMARY KEY  (id),
  INDEX (name)
) ENGINE=InnoDB;

INSERT INTO t2 VALUES (1,'A1'),(2,'A2'),(3,'B');

DROP TABLE IF EXISTS t1;
CREATE TABLE t1 (
  id int(11) NOT NULL,
  fkey int(11),
  PRIMARY KEY  (id),
  FOREIGN KEY (fkey) REFERENCES t2(id)
) ENGINE=InnoDB;

INSERT INTO t1 VALUES (1,1),(2,2),(3,2),(4,3),(5,3);

EXPLAIN
  SELECT
    COUNT(*)
  FROM
    t1
    LEFT JOIN t2 ON t1.fkey = t2.id
  WHERE
    t2.name LIKE 'A%' \G

EXPLAIN
  SELECT
    COUNT(*)
  FROM
    t1
    LEFT JOIN t2 ON t1.fkey = t2.id
  WHERE
    (t2.name LIKE 'A%' OR FALSE) \G