Change the page cache so that a new sqlite3_pcache object is allocated as
soon as the page cache is opened, not delayed until the first fetch request.
This give a noticable performance boost.  The interface between pager and
the page cache has changed slightly, which might break ZIPVFS.
Performance enhancement in sqlite3VdbeMemNulTerminate().
Factor out the exception paths from sqlite3ValueToText() into a separate
function so that the main routine is much faster for the common case of
no required type or encoding conversions.
In the sqlite3_context object, keep a pointer to the result value rather
than storing the result value in the sqlite3_context object and using
memcpy() to move the value back into its register
after the function returns.  This runs faster and saves over 500 bytes
of code space.
When determining whether or not a partial index is usable, do not assume that the cursor number assigned to each table in the query is the same as its index in the FROM clause. Fix for ticket [98d973b8f5].
Add a missing ticket number to a comment in index7.test.
Add a VDBE synopsis comment for clarification.
Refactor the sqlite3PcacheFetch() routine into three separate routines,
which are significantly faster overall and about 100 bytes smaller in
size as well.
Fix a formatting error ("%d" needed in place of "%g") on a WHERETRACE
macro inside of the query planner.  This fix applies to debugging logic
only.
Fix a problem causing an inaccurate stat4-based estimate for the number of rows visited by a range scan.
Add a testcase() macro to help verfity the row estimation logic.
Fix a problem causing an inaccurate stat4-based estimate for the
number of rows visited by a range scan.
Improved WHERETRACE messages for the estimated output row reductions from
range scans.
Avoid an unnecessary OP_Move operation for expression subqueries.
Note a fault after all, rather a testing mistake.
Move this change back to trunk.
Was: Avoid an unnecessary OP_Move operation for expression subqueries.
Merge recent performance enhancements from trunk onto the threads branch.
Add SQLITE_LIMIT_WORKER_THREADS for controlling the maximum number of
worker threads.
Fix the speedtest1.c test program to set the worker thread count using
the threads pragma.
Disable worker threads when SQLITE_THREADSAFE=0.  Set the default compile-time
maximum number of worker threads to 8 and honor the
SQLITE_DEFAULT_WORKER_THREADS compile-time constant (which defaults to 0).