Android SQLite Select query speed
Try not using nested SELECT statments, instead see if you can use JOIN.
Example:
SELECT * FROM Songs AS s1 JOIN Songs AS s2 ON s1.KEY_ID = s2.KEY_ID WHERE length (s2.KEY_SONGPATH) >= " + strLength + ") AND s1.KEY_SONGPATH LIKE '" + currentDir + "%'
Don't use a subquery; it doesn't make anything faster because it still has to do the same checks.
Dont use LENGTH(column) >= value because it isn't faster than the LIKE check, and cannot be indexed.
To speed up the LIKE, put an index on the KEY_ID column.Because LIKE is case-insensitive by default, you have to use COLLATE NOCASE when creating the index(see the CREATE INDEX documentation).