SQLite version 3.6.16 is another general maintenance relase containing performance and robustness enhancements. A single notable bug was fixed (ticket #3929). This bug cause cause INSERT or UPDATE statements to fail on indexed tables that have AFTER triggers that modify the same table and index.
SQLite version 3.6.15 is a general maintenance release containing performance and robustness enhancements and fixes for various obscure bugs.
SQLite version 220.127.116.11 fixes an obscure bug in the code generator (ticket #3879) section of SQLite which can potentially cause incorrect query results. The changes from the prior release consist of only this one bug fix, check-in  and a change to the version number text.
The bug was introduced in version 3.6.14. It is recommended that users of version 3.6.14 and 18.104.22.168 upgrade to this release. Applications are unlikely to hit this bug, but since it is difficult to predict which applications might hit it and which might not, we recommend that all users of 3.6.14 and 22.214.171.124 upgrade to this release.
SQLite version 3.6.14 provides new performance enhancements in the btree and pager layers and in the query optimizer. Certain workloads can be as much as twice as fast as the previous release, though 10% faster is a more typical result.
Queries against virtual tables that contain OR and IN operators in the WHERE clause are now able to use indexing.
A new optional asynchronous I/O backend is available for unix and windows. The asynchronous backend gives the illusion of faster response time by pushing slow write operations into a background thread. The tradeoff for faster response time is that more memory is required (to hold the content of the pending writes) and if a power failure or program crash occurs, some transactions that appeared to have committed might end up being rolled back upon restart.
This release also contains many minor bug fixes, documentation enhancements, new test cases, and cleanups and simplifications to the source code.
There is no compelling reason to upgrade from versions 3.6.12 or 3.6.13 if those prior versions are working. Though many users may benefit from the improved performance.
SQLite version 3.6.13 fixes several minor issues that appeared in previous version, including Ticket #3774, ticket #3791, and ticket #3777. This is a bug-fix release only. There are no new features or enhancements.
SQLite version 3.6.12 fixes a database corruption bug. If an incremental_vacuum is rolled back in an in-memory database, the database will often go corrupt. This only happens for in-memory databases. On-disk databases are unaffected. And the corruption only appears if an incremental vacuum is rolled back. Nevertheless, upgrading is recommended for all applications, especially those that make use of in-memory databases and/or incremental vacuum. See ticket #3761.
SQLite version 3.6.12 also adds support for the sqlite3_unlock_notify() interface and the reverse_unordered_selects pragma and the new ".genfkey" command in the CLI. There are also performance improvements in many count(*) SQL statements.
During testing of version 3.6.12, a bug in the lookaside memory allocator as it relates to shared cache mode was found that effects all prior versions of SQLite back to version 3.6.1. If you are using shared cache mode you should either disable lookaside memory allocation or upgrade to version 3.6.12. See ticket #3743.
SQLite version 3.6.11 adds support for the hot-backup interface. This interface can be used to create a backup copy of an SQLite database while it is in use. The same interface can be used to initialize an in-memory database from a persistent disk image or to save an in-memory database into a persistent disk image. Usage examples can be found at Using the SQLite Online Backup API.
SQLite version 3.6.10 fixes a cache coherency bug (Ticket #3584) introduced by check-in  which was part of version 3.6.5. This bug might lead to database corruption, hence we felt it was important to get it out as quickly as possible, even though there had already been two prior releases this week.
Some concern has been expressed that we are releasing too frequently. (Three releases in one week is a lot!) The concern is that this creates the impression of volatility and unreliability. We have been told that we should delay releases in order to create the impression of stability. But the SQLite developers feel that truth is more important than perception, not the other way around. We think it is important to make the highest quality and most stable version of SQLite available to users at all times. This week has seen two important bugs being discovered shortly after a major release, and so we have issued two emergency patch releases after the regularly scheduled major release. This makes us look bad. This puts "egg on our face." We do not like that. But, three releases also ensures that the best quality SQLite code base is available available to you at all times.
It has been suggested that "beta" releases might find these kinds of bugs prior to a major release. But our experience indicates otherwise. The two issues that prompted releases 3.6.9 and 3.6.10 were both discovered by internal testing and review - not by external users. And, indeed, most the problems found in SQLite these days are discovered by our rigorous internal testing protocol, not bug reports from the field.
It has also been argued that we should withhold releases "until testing is finished." The fallacy there is that we never finish testing. We are constantly writing new test cases for SQLite and thinking of new ways to stress and potentially break the code. This is a continuous, never-ending, and on-going process. All existing tests pass before each release. But we will always be writing new tests the day after a release, regardless of how long we delay that release. And sometimes those new tests will uncover new problems.
All this is to say that we believe that SQLite version 3.6.10 is the most stable, most thoroughly tested, and bug-free version of SQLite that has ever existed. Please do not be freaked out by three releases occurring in one week.
Internal stress testing revealed a corner case where the cost function on the query optimizer might mislead the query optimizer into making a poor indexing choice. That choice could then tickle another bug in the VDBE which might result in an incorrect query result. This release fixes both problems. The chances of actually hitting this combination of problems in a real application seems remote. Nevertheless upgrading is recommended.
SQLite version 3.6.8 adds support for nested transactions and improved optimization of WHERE clauses with OR-connected terms. There is also a new compile-time option that changes the way full-text search patterns are parsed so that they can contain nested parentheses.
These are substantial changes. Even so, the release testing for SQLite has become so extensive that the developers have high confidence that this release is stable and ready for production use.