Fix a bug (ticket #2273)
+ that could cause a segfault when the IN operator
+ is used one term of a two-column index and the right-hand side of
+ the IN operator contains a NULL.
+
Added a new OS interface method for determining the sector size
+ of underlying media: sqlite3OsSectorSize().
+
A new algorithm for statements of the form
+ INSERT INTO table1 SELECT * FROM table2
+ is faster and reduces fragmentation. VACUUM uses statements of
+ this form and thus runs faster and defragments better.
+
Performance enhancements through reductions in disk I/O:
+
+
Do not read the last page of an overflow chain when
+ deleting the row - just add that page to the freelist.
+
Do not store pages being deleted in the
+ rollback journal.
+
Do not read in the (meaningless) content of
+ pages extracted from the freelist.
+
Do not flush the page cache (and thus avoiding
+ a cache refill) unless another process changes the underlying
+ database file.
+
Truncate rather than delete the rollback journal when committing
+ a transaction in exclusive access mode, or when committing the TEMP
+ database.