Is an index needed for a primary key in SQLite?

Question

When an integer column is marked as a primary key in an SQLite table, should an index be explicitly created for it as well? SQLite does not appear to automatically create an

Answer 1

If an column is marked INTEGER PRIMARY KEY, it's actually around twice as fast as a similar search made by specifying any other PRIMARY KEY or indexed value. This is because:

...all rows within SQLite tables have a 64-bit signed integer key that uniquely identifies the row within its table ... Searching for a record with a specific rowid, or for all records with rowids within a specified range is around twice as fast as a similar search made by specifying any other PRIMARY KEY or indexed value.

With one exception noted below, if a rowid table has a primary key that consists of a single column and the declared type of that column is "INTEGER" in any mixture of upper and lower case, then the column becomes an alias for the rowid.

Such a column is usually referred to as an "integer primary key". A PRIMARY KEY column only becomes an integer primary key if the declared type name is exactly "INTEGER". Other integer type names like "INT" or "BIGINT" or "SHORT INTEGER" or "UNSIGNED INTEGER" causes the primary key column to behave as an ordinary table column with integer affinity and a unique index, not as an alias for the rowid.

See: http://www.sqlite.org/lang_createtable.html#rowid