Documentation Source Text

Artifact [55d7c2c684]

Artifact 55d7c2c6845d59080a19284cdbc3c87622c1747f:

<title>Recent SQLite News</title>

<h2>Recent News</h2>

proc newsitem {date title text} {
  regsub -all {[^a-z0-9]} [string tolower $date] _ tag
  hd_puts "<a name=\"$tag\"></a>"
  if {![regsub -all {(Version) (\d+)\.(\d+)\.(\d+)\.(\d+)} $title \
        {<a href="releaselog/\2_\3_\4_\5.html">\0</a>} title]} {
    regsub -all {(Version) (\d+)\.(\d+)\.(\d+)} $title \
      {<a href="releaselog/\2_\3_\4.html">\0</a>} title
  hd_puts "<h3>$date - $title</h3>"
  regsub -all "\n( *\n)+" $text "</p>\n\n<p>" txt
  regsub -all {[Tt]icket #(\d+)} $txt \
      {<a href="\1">\0</a>} txt
  hd_resolve "<blockquote>$txt</blockquote>"
  hd_puts "<hr width=\"50%\">"

newsitem {2014-04-03} {Release} {
<p>The optimizations added in [version 3.8.4] caused some queries that involve
   subqueries in the FROM clause, DISTINCT, and ORDER BY clauses, to give an incorrect
   result.  See
   [| ticket 98825a79ce145]
   for details.
   This release adds a 
   [|one-character change]
   to a single line of code to fix the problem.

newsitem {2014-03-26} {Release} {
<p>The code changes that resulted in the performance improvements
   in [version 3.8.4] missed a single buffer overflow test, which could
   result in a read past the end of a buffer while searching a database
   that is corrupted in a particular way.  [Version] fixes that
   problem using a
   [|one-line patch].

<p>We are not aware of any problems in [version 3.8.4]
   when working with well-formed database files.  The problem fixed by this
   release only comes up when reading corrupt database files.

newsitem {2014-03-11} {Release} {
<p>SQLite [version] is a patch against [version 3.8.4] that fixes
   two minor issues:
<li> Work around a C-preprocessor macro conflict that causes compilation
     problems for some configurations of Visual Studio.
<li> Adjust the cost computation for the [skip-scan optimization] for
     improved performance.
Both of these issues came to light within minutes of tagging the previous
release.  Neither issue is serious but they can be annoying.  Hence, the
decision was made to do a quick patch release to address both issues.

newsitem {2014-03-10} {Release 3.8.4} {
<p>SQLite [version 3.8.4] is a maintenance release featuring performance
   enhancements and fixes for a number of obscure bugs.
   There are no significant new features in SQLite version 3.8.4.
   However, the number of CPU cycles (measured by valgrind) needed to 
   do many common operations has be reduced by about 12% relative to the
   previous release, and by about 25% relative to [version 3.7.16]
   from approximately one year ago.

<p>Version 3.8.4 of SQLite fixes several corner-case bugs that were
   found since the previous release.  These bugs were unlikely to appear
   in practice, and none represent a security vulnerability. 
   Nevertheless, developers are encouraged to upgrade from all prior releases.

newsitem {2014-02-11} {Release} {
<p>SQLite [version] fixes a bug present in versions 3.8.1,
   3.8.2 and 3.8.3 that can cause queries to omit valid output rows.
   Upgrading from those versions is recommended.
<p>The problem only comes up if SQLite is compiled with either the
   [SQLITE_ENABLE_STAT3] or [SQLITE_ENABLE_STAT4] compile-time options.
   In that case, if a query has a WHERE clause that contains expressions
   like this:
WHERE (expr1 OR expr2 OR ... OR exprN) AND column IS NOT NULL
   Where all of expr1 through exprN are suitable for use by indexes,
   then during query planning SQLite might mistakenly converted
   the "column IS NOT NULL" term into "column>NULL".  But the latter
   term is never true, and so the query would return no rows.

<p>The trouble ticket for this bug is
   It is recommended that all users upgrade to avoid this problem.

newsitem {2014-02-03} {Release 3.8.3} {
  <p>SQLite [version 3.8.3] is a regularly scheduled maintenance release.
  Upgrading from the previous release is optional.

  <p>The most visible change in version 3.8.3 is the addition of
  support for [common table expressions].  It is now possible to write a
  single [SELECT] statement that will query a tree or graph, using either
  a depth-first or a breadth-first search.  A single SQLite query will 
  even [solve Sudoku puzzles] or [compute the Mandelbrot set].  As part
  of this change, SQLite now accepts a [VALUES clause] anyplace that
  a [SELECT] statement is valid.

  <p>This release also includes many small performance enhancements which
  should give a small speed boost to legacy applications.  And there are
  other minor enhancements such as the addition of the [printf()] SQL
  function.  See the [version 3.8.3|change log] for details.

newsitem {2013-12-06} {Release 3.8.2} {
  <p>SQLite [version 3.8.2] is a regularly scheduled maintenance release.
  Upgrading from the previous release is optional.

  <p>Version 3.8.2 adds support for [WITHOUT ROWID] tables.  This is a
  significant extension to SQLite.  Database files that contain WITHOUT ROWID
  tables are not readable or writable by prior versions of SQLite, however
  databases that do not use WITHOUT ROWID tables are fully backwards 
  and forwards compatible.

  <p>The 3.8.2 release contains a potentially incompatible change.  In
  all prior versions of SQLite, a [cast] from a very large positive 
  floating point number into an integer resulted in the most negative integer.
  In other words, CAST(+99.9e99 to INT) would yield -9223372036854775808.
  This behavior came about because it is what x86/x64 hardware does 
  for the equivalent cast in the C language.  But the behavior is
  bizarre.  And so it has been changed effective with this release so that
  a cast from a floating point number into an integer returns the integer
  between the floating point value and zero that is closest to the floating
  point value.  Hence, CAST(+99.9e99 to INT) now returns +9223372036854775807.
  Since routines like [sqlite3_column_int64()] do an implicit cast if the
  value being accessed is really a floating point number, they are also
  affected by this change.

  <p>Besides the two changes mentioned above, the 3.8.2 release also 
  includes a number of performance enhancements.  The
  [skip-scan optimization] is now available for databases that have been
  processed by [ANALYZE].  Constant SQL functions are now factored out of
  inner loops, which can result in a significant speedup for queries that
  contain WHERE clause terms like "date>datetime('now','-2 days')".  And
  various high-runner internal routines have been refactored for reduced
  CPU load.

newsitem {2013-10-17} {Release 3.8.1} {
  <p>SQLite [version 3.8.1] is a regularly scheduled maintenance release.
  Upgrading from the previous release is optional, though you should upgrade
  if you are using [partial indices] as there was a 
  [|bug] related to partial
  indices in the previous release that could result in an incorrect answer
  for count(*) queries.

  <p>The [next generation query planner] that was premiered in the previous
  release continues to work well.  
  The new query planner has been tweaked slightly
  in the current release to help it make better decisions in some
  cases, but is largely unchanged.  Two new SQL functions, [likelihood()] and
  [unlikely()], have been added to allow developers to give hints to the
  query planner without forcing the query planner into a particular decision.

  <p>Version 3.8.1 is the first SQLite release to take into account the
  estimated size of table and index rows when choosing a query plan.
  Row size estimates are based on the declared datatypes of columns.
  For example, a column of type VARCHAR(1000) is assumed
  to use much more space than a column of type INT.  The datatype-based
  row size estimate can be
  overridden by appending a term of the form "sz=NNN" (where NNN is the
  average row size in bytes) to the end of the [sqlite_stat1|sqlite_stat1.stat]
  record for a table or index.  Currently, row sizes are only used to help the
  query planner choose between a table or one of its indices when doing a
  table scan or a count(*) operation, though future releases are likely
  to use the estimated row size in other contexts as well.  The new
  [PRAGMA stats] statement can be used to view row size estimates.

  <p>Version 3.8.1 adds the [SQLITE_ENABLE_STAT4] compile-time option.
  STAT4 is very similar to STAT3 in that it uses samples from indices to 
  try to guess how many rows of the index will be satisfy by WHERE clause
  constraints.  The difference is that STAT4 samples all columns of the
  index whereas the older STAT3 only sampled the left-most column.  Users
  of STAT3 are encouraged to upgrade to STAT4.  Application developers should
  use STAT3 and STAT4 with caution since both options, by design, violate 
  the [query planner stability guarantee], making it more difficult to ensure
  uniform performance is widely-deployed and mass-produced embedded

newsitem {2013-09-03} {Release} {
  <p>SQLite [version] contains a one-line fix to a bug in the
  new optimization that tries to omit unused LEFT JOINs from a query.

newsitem {2013-08-29} {Release} {
  <p>SQLite [version] fixes some obscure bugs that were uncovered by
  users in the 3.8.0 release.  Changes from 3.8.0 are minimal.

newsitem {2013-08-26} {Release 3.8.0} {
  <b>Do not fear the zero!</b>

  <p>SQLite [version 3.8.0] might easily have been called "3.7.18" instead.
  However, this release features the cutover of the
  [next generation query planner] or [NGQP], and there is a small chance of
  [hazards of upgrading to the NGQP | breaking legacy programs] that
  rely on undefined behavior in previous SQLite releases, and so the
  minor version number was incremented for that reason.
  But the risks are low and there is a [query planner checklist] is 
  available to application developers to aid in avoiding problems.

  <p>SQLite [version 3.8.0] is actually one of the most heavily tested
  SQLite releases ever.  Thousands and thousands of beta copies have
  be downloaded, and presumably tested, and there have been no problem

  <p>In addition to the [next generation query planner], the 3.8.0 release
  adds support for [partial indices], as well as several other new features.
  See the [version 3.8.0 | change log] for further detail.

newsitem {2013-05-20} {Release 3.7.17} {
  SQLite [version 3.7.17] is a regularly schedule maintenance release.
  Visit the [version 3.7.17 | change log] for a full explanation of the
  changes in this release.

  There are many bug fixes in version 3.7.17.  But this does not indicate
  that 3.7.16 was a problematic release.  All of the bugs in 3.7.17 are 
  obscure and are unlikely to impact any particular application.  And most 
  of the bugs that are fixed in 3.7.17 predate 3.7.16 and have been in 
  the code for years without ever before being noticed.
  Nevertheless, due to the large number of fixes,
  all users are encouraged to upgrade when possible.

newsitem {2013-04-12} {Release} {
  SQLite [version] fixes a long-standing flaw in the Windows
  OS interface that
  can result in database corruption under a rare race condition.
  See [] for a full description
  of the problem.

  As far as we know, this bug has never been seen in the wild.  The
  problem was discovered by the SQLite developers while writing stress tests
  for a separate component of SQLite.  Those stress tests have not yet
  found any problems with the component they were intended to verify, but 
  they did find the bug which is the subject of this patch release.

  Other than updates to version numbers, the only difference between this
  release and is a two-character change in a single identifier,
  which is contained in the windows-specific OS interface logic.  There 
  are no changes in this release (other than version numbers) for platforms
  other than Windows.

newsitem {2013-03-29} {Release} {
  SQLite [version] is a bug fix release that fixes a few problems
  that were present in the previous releases.

  The primary motivation for version is to fix a bug in the
  query optimizer that was introduced as part of [version 3.7.15].  The
  query optimizer was being a little overzealous in optimizing out some
  ORDER BY clauses, which resulted in sorting being omitted on occasions
  where sorting is required to get the correct answer.  See
  ticket [ | a179fe7465] for

  In addition to the ORDER BY fix, several other patches to fix obscure
  (and mostly harmless) bugs and to fix spelling errors in source code
  comments are also included in this release.

newsitem {2013-03-18} {Release 3.7.16} {
  SQLite [version 3.7.16] is a regularly scheduled release of SQLite.
  This release contains several language enhancements and improvements
  to the query optimizer.  A list of the major enhancements and optimizations
  can be see on the [version 3.7.16 | change log].

  There was one important bug fix
  (see [ | Ticket fc7bd6358f])
  that addresses an incorrect query result that could have occurred in
  a three-way join where the join constraints compared INTEGER columns
  to TEXT columns.  This issue had been in the code for time out of mind
  and had never before been reported, so we surmise that it is very obscure.
  Nevertheless, all users are advised to upgrade to avoid any future problems
  associated with this issue.

newsitem {2013-01-09} {Release} {
  SQLite [version] is a patch release that fixes a single bug
  that was introduced in version [version 3.7.15].  The fix is a 4-character
  edit to a single line of code.  Other than this 4-character change and
  the update of the version number, nothing has changed from


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