[sql] Import SQLite 3.17.0.

third_party/sqlite/src/src/sqlite.h.in

Index: third_party/sqlite/src/src/sqlite.h.in
diff --git a/third_party/sqlite/src/src/sqlite.h.in b/third_party/sqlite/src/src/sqlite.h.in
index e5673fd93f3400a9ccd8412b7e9dee907ef9bcff..fbbf4b9f2db3b9745fdbcaea98df8a1f32d57d0f 100644
--- a/third_party/sqlite/src/src/sqlite.h.in
+++ b/third_party/sqlite/src/src/sqlite.h.in
@@ -30,8 +30,8 @@
 ** the version number) and changes its name to "sqlite3.h" as
 ** part of the build process.
 */
-#ifndef _SQLITE3_H_
-#define _SQLITE3_H_
+#ifndef SQLITE3_H
+#define SQLITE3_H
 #include <stdarg.h>     /* Needed for the definition of va_list */
 
 /*
@@ -54,8 +54,17 @@ extern "C" {
 #ifndef SQLITE_CDECL
 # define SQLITE_CDECL
 #endif
+#ifndef SQLITE_APICALL
+# define SQLITE_APICALL
+#endif
 #ifndef SQLITE_STDCALL
-# define SQLITE_STDCALL
+# define SQLITE_STDCALL SQLITE_APICALL
+#endif
+#ifndef SQLITE_CALLBACK
+# define SQLITE_CALLBACK
+#endif
+#ifndef SQLITE_SYSAPI
+# define SQLITE_SYSAPI
 #endif
 
 /*
@@ -99,7 +108,8 @@ extern "C" {
 ** be held constant and Z will be incremented or else Y will be incremented
 ** and Z will be reset to zero.
 **
-** Since version 3.6.18, SQLite source code has been stored in the
+** Since [version 3.6.18] ([dateof:3.6.18]), 
+** SQLite source code has been stored in the
 ** <a href="http://www.fossil-scm.org/">Fossil configuration management
 ** system</a>.  ^The SQLITE_SOURCE_ID macro evaluates to
 ** a string which identifies a particular check-in of SQLite
@@ -117,7 +127,7 @@ extern "C" {
 
 /*
 ** CAPI3REF: Run-Time Library Version Numbers
-** KEYWORDS: sqlite3_version, sqlite3_sourceid
+** KEYWORDS: sqlite3_version sqlite3_sourceid
 **
 ** These interfaces provide the same information as the [SQLITE_VERSION],
 ** [SQLITE_VERSION_NUMBER], and [SQLITE_SOURCE_ID] C preprocessor macros
@@ -249,7 +259,11 @@ typedef struct sqlite3 sqlite3;
 */
 #ifdef SQLITE_INT64_TYPE
   typedef SQLITE_INT64_TYPE sqlite_int64;
-  typedef unsigned SQLITE_INT64_TYPE sqlite_uint64;
+# ifdef SQLITE_UINT64_TYPE
+    typedef SQLITE_UINT64_TYPE sqlite_uint64;
+# else  
+    typedef unsigned SQLITE_INT64_TYPE sqlite_uint64;
+# endif
 #elif defined(_MSC_VER) || defined(__BORLANDC__)
   typedef __int64 sqlite_int64;
   typedef unsigned __int64 sqlite_uint64;
@@ -347,7 +361,7 @@ typedef int (*sqlite3_callback)(void*,int,char**, char**);
 ** from [sqlite3_malloc()] and passed back through the 5th parameter.
 ** To avoid memory leaks, the application should invoke [sqlite3_free()]
 ** on error message strings returned through the 5th parameter of
-** of sqlite3_exec() after the error message string is no longer needed.
+** sqlite3_exec() after the error message string is no longer needed.
 ** ^If the 5th parameter to sqlite3_exec() is not NULL and no errors
 ** occur, then sqlite3_exec() sets the pointer in its 5th parameter to
 ** NULL before returning.
@@ -443,7 +457,8 @@ int sqlite3_exec(
 ** [result codes].  However, experience has shown that many of
 ** these result codes are too coarse-grained.  They do not provide as
 ** much information about problems as programmers might like.  In an effort to
-** address this, newer versions of SQLite (version 3.3.8 and later) include
+** address this, newer versions of SQLite (version 3.3.8 [dateof:3.3.8]
+** and later) include
 ** support for additional result codes that provide more detailed information
 ** about errors. These [extended result codes] are enabled or disabled
 ** on a per database connection basis using the
@@ -506,6 +521,7 @@ int sqlite3_exec(
 #define SQLITE_NOTICE_RECOVER_ROLLBACK (SQLITE_NOTICE | (2<<8))
 #define SQLITE_WARNING_AUTOINDEX       (SQLITE_WARNING | (1<<8))
 #define SQLITE_AUTH_USER               (SQLITE_AUTH | (1<<8))
+#define SQLITE_OK_LOAD_PERMANENTLY     (SQLITE_OK | (1<<8))
 
 /*
 ** CAPI3REF: Flags For File Open Operations
@@ -560,7 +576,7 @@ int sqlite3_exec(
 ** file that were written at the application level might have changed
 ** and that adjacent bytes, even bytes within the same sector are
 ** guaranteed to be unchanged.  The SQLITE_IOCAP_UNDELETABLE_WHEN_OPEN
-** flag indicate that a file cannot be deleted when open.  The
+** flag indicates that a file cannot be deleted when open.  The
 ** SQLITE_IOCAP_IMMUTABLE flag indicates that the file is on
 ** read-only media and cannot be changed even by processes with
 ** elevated privileges.
@@ -710,6 +726,9 @@ struct sqlite3_file {
 ** <li> [SQLITE_IOCAP_ATOMIC64K]
 ** <li> [SQLITE_IOCAP_SAFE_APPEND]
 ** <li> [SQLITE_IOCAP_SEQUENTIAL]
+** <li> [SQLITE_IOCAP_UNDELETABLE_WHEN_OPEN]
+** <li> [SQLITE_IOCAP_POWERSAFE_OVERWRITE]
+** <li> [SQLITE_IOCAP_IMMUTABLE]
 ** </ul>
 **
 ** The SQLITE_IOCAP_ATOMIC property means that all writes of
@@ -966,6 +985,12 @@ struct sqlite3_io_methods {
 ** on whether or not the file has been renamed, moved, or deleted since it
 ** was first opened.
 **
+** <li>[[SQLITE_FCNTL_WIN32_GET_HANDLE]]
+** The [SQLITE_FCNTL_WIN32_GET_HANDLE] opcode can be used to obtain the
+** underlying native file handle associated with a file handle.  This file
+** control interprets its argument as a pointer to a native file handle and
+** writes the resulting value there.
+**
 ** <li>[[SQLITE_FCNTL_WIN32_SET_HANDLE]]
 ** The [SQLITE_FCNTL_WIN32_SET_HANDLE] opcode is used for debugging.  This
 ** opcode causes the xFileControl method to swap the file handle with the one
@@ -1016,6 +1041,8 @@ struct sqlite3_io_methods {
 #define SQLITE_FCNTL_RBU                    26
 #define SQLITE_FCNTL_VFS_POINTER            27
 #define SQLITE_FCNTL_JOURNAL_POINTER        28
+#define SQLITE_FCNTL_WIN32_GET_HANDLE       29
+#define SQLITE_FCNTL_PDB                    30
 
 /* deprecated names */
 #define SQLITE_GET_LOCKPROXYFILE      SQLITE_FCNTL_GET_LOCKPROXYFILE
@@ -1036,6 +1063,16 @@ struct sqlite3_io_methods {
 typedef struct sqlite3_mutex sqlite3_mutex;
 
 /*
+** CAPI3REF: Loadable Extension Thunk
+**
+** A pointer to the opaque sqlite3_api_routines structure is passed as
+** the third parameter to entry points of [loadable extensions].  This
+** structure must be typedefed in order to work around compiler warnings
+** on some platforms.
+*/
+typedef struct sqlite3_api_routines sqlite3_api_routines;
+
+/*
 ** CAPI3REF: OS Interface Object
 **
 ** An instance of the sqlite3_vfs object defines the interface between
@@ -1228,7 +1265,7 @@ struct sqlite3_vfs {
   const char *(*xNextSystemCall)(sqlite3_vfs*, const char *zName);
   /*
   ** The methods above are in versions 1 through 3 of the sqlite_vfs object.
-  ** New fields may be appended in figure versions.  The iVersion
+  ** New fields may be appended in future versions.  The iVersion
   ** value will increment whenever this happens. 
   */
 };
@@ -1820,6 +1857,20 @@ struct sqlite3_mem_methods {
 ** is enabled (using the [PRAGMA threads] command) and the amount of content
 ** to be sorted exceeds the page size times the minimum of the
 ** [PRAGMA cache_size] setting and this value.
+**
+** [[SQLITE_CONFIG_STMTJRNL_SPILL]]
+** <dt>SQLITE_CONFIG_STMTJRNL_SPILL
+** <dd>^The SQLITE_CONFIG_STMTJRNL_SPILL option takes a single parameter which
+** becomes the [statement journal] spill-to-disk threshold.  
+** [Statement journals] are held in memory until their size (in bytes)
+** exceeds this threshold, at which point they are written to disk.
+** Or if the threshold is -1, statement journals are always held
+** exclusively in memory.
+** Since many statement journals never become large, setting the spill
+** threshold to a value such as 64KiB can greatly reduce the amount of
+** I/O required to support statement rollback.
+** The default value for this setting is controlled by the
+** [SQLITE_STMTJRNL_SPILL] compile-time option.
 ** </dl>
 */
 #define SQLITE_CONFIG_SINGLETHREAD  1  /* nil */
@@ -1847,6 +1898,7 @@ struct sqlite3_mem_methods {
 #define SQLITE_CONFIG_WIN32_HEAPSIZE      23  /* int nByte */
 #define SQLITE_CONFIG_PCACHE_HDRSZ        24  /* int *psz */
 #define SQLITE_CONFIG_PMASZ               25  /* unsigned int szPma */
+#define SQLITE_CONFIG_STMTJRNL_SPILL      26  /* int nByte */
 
 /*
 ** CAPI3REF: Database Connection Configuration Options
@@ -1904,11 +1956,66 @@ struct sqlite3_mem_methods {
 ** following this call.  The second parameter may be a NULL pointer, in
 ** which case the trigger setting is not reported back. </dd>
 **
+** <dt>SQLITE_DBCONFIG_ENABLE_FTS3_TOKENIZER</dt>
+** <dd> ^This option is used to enable or disable the two-argument
+** version of the [fts3_tokenizer()] function which is part of the
+** [FTS3] full-text search engine extension.
+** There should be two additional arguments.
+** The first argument is an integer which is 0 to disable fts3_tokenizer() or
+** positive to enable fts3_tokenizer() or negative to leave the setting
+** unchanged.
+** The second parameter is a pointer to an integer into which
+** is written 0 or 1 to indicate whether fts3_tokenizer is disabled or enabled
+** following this call.  The second parameter may be a NULL pointer, in
+** which case the new setting is not reported back. </dd>
+**
+** <dt>SQLITE_DBCONFIG_ENABLE_LOAD_EXTENSION</dt>
+** <dd> ^This option is used to enable or disable the [sqlite3_load_extension()]
+** interface independently of the [load_extension()] SQL function.
+** The [sqlite3_enable_load_extension()] API enables or disables both the
+** C-API [sqlite3_load_extension()] and the SQL function [load_extension()].
+** There should be two additional arguments.
+** When the first argument to this interface is 1, then only the C-API is
+** enabled and the SQL function remains disabled.  If the first argument to
+** this interface is 0, then both the C-API and the SQL function are disabled.
+** If the first argument is -1, then no changes are made to state of either the
+** C-API or the SQL function.
+** The second parameter is a pointer to an integer into which
+** is written 0 or 1 to indicate whether [sqlite3_load_extension()] interface
+** is disabled or enabled following this call.  The second parameter may
+** be a NULL pointer, in which case the new setting is not reported back.
+** </dd>
+**
+** <dt>SQLITE_DBCONFIG_MAINDBNAME</dt>
+** <dd> ^This option is used to change the name of the "main" database
+** schema.  ^The sole argument is a pointer to a constant UTF8 string
+** which will become the new schema name in place of "main".  ^SQLite
+** does not make a copy of the new main schema name string, so the application
+** must ensure that the argument passed into this DBCONFIG option is unchanged
+** until after the database connection closes.
+** </dd>
+**
+** <dt>SQLITE_DBCONFIG_NO_CKPT_ON_CLOSE</dt>
+** <dd> Usually, when a database in wal mode is closed or detached from a 
+** database handle, SQLite checks if this will mean that there are now no 
+** connections at all to the database. If so, it performs a checkpoint 
+** operation before closing the connection. This option may be used to
+** override this behaviour. The first parameter passed to this operation
+** is an integer - non-zero to disable checkpoints-on-close, or zero (the
+** default) to enable them. The second parameter is a pointer to an integer
+** into which is written 0 or 1 to indicate whether checkpoints-on-close
+** have been disabled - 0 if they are not disabled, 1 if they are.
+** </dd>
+**
 ** </dl>
 */
-#define SQLITE_DBCONFIG_LOOKASIDE       1001  /* void* int int */
-#define SQLITE_DBCONFIG_ENABLE_FKEY     1002  /* int int* */
-#define SQLITE_DBCONFIG_ENABLE_TRIGGER  1003  /* int int* */
+#define SQLITE_DBCONFIG_MAINDBNAME            1000 /* const char* */
+#define SQLITE_DBCONFIG_LOOKASIDE             1001 /* void* int int */
+#define SQLITE_DBCONFIG_ENABLE_FKEY           1002 /* int int* */
+#define SQLITE_DBCONFIG_ENABLE_TRIGGER        1003 /* int int* */
+#define SQLITE_DBCONFIG_ENABLE_FTS3_TOKENIZER 1004 /* int int* */
+#define SQLITE_DBCONFIG_ENABLE_LOAD_EXTENSION 1005 /* int int* */
+#define SQLITE_DBCONFIG_NO_CKPT_ON_CLOSE      1006 /* int int* */
 
 
 /*
@@ -2185,7 +2292,7 @@ int sqlite3_complete16(const void *sql);
 ** A busy handler must not close the database connection
 ** or [prepared statement] that invoked the busy handler.
 */
-int sqlite3_busy_handler(sqlite3*, int(*)(void*,int), void*);
+int sqlite3_busy_handler(sqlite3*,int(*)(void*,int),void*);
 
 /*
 ** CAPI3REF: Set A Busy Timeout
@@ -2707,6 +2814,9 @@ int sqlite3_set_authorizer(
 ** CAPI3REF: Tracing And Profiling Functions
 ** METHOD: sqlite3
 **
+** These routines are deprecated. Use the [sqlite3_trace_v2()] interface
+** instead of the routines described here.
+**
 ** These routines register callback functions that can be used for
 ** tracing and profiling the execution of SQL statements.
 **
@@ -2732,11 +2842,105 @@ int sqlite3_set_authorizer(
 ** sqlite3_profile() function is considered experimental and is
 ** subject to change in future versions of SQLite.
 */
-void *sqlite3_trace(sqlite3*, void(*xTrace)(void*,const char*), void*);
-SQLITE_EXPERIMENTAL void *sqlite3_profile(sqlite3*,
+SQLITE_DEPRECATED void *sqlite3_trace(sqlite3*,
+   void(*xTrace)(void*,const char*), void*);
+SQLITE_DEPRECATED void *sqlite3_profile(sqlite3*,
    void(*xProfile)(void*,const char*,sqlite3_uint64), void*);
 
 /*
+** CAPI3REF: SQL Trace Event Codes
+** KEYWORDS: SQLITE_TRACE
+**
+** These constants identify classes of events that can be monitored
+** using the [sqlite3_trace_v2()] tracing logic.  The third argument
+** to [sqlite3_trace_v2()] is an OR-ed combination of one or more of
+** the following constants.  ^The first argument to the trace callback
+** is one of the following constants.
+**
+** New tracing constants may be added in future releases.
+**
+** ^A trace callback has four arguments: xCallback(T,C,P,X).
+** ^The T argument is one of the integer type codes above.
+** ^The C argument is a copy of the context pointer passed in as the
+** fourth argument to [sqlite3_trace_v2()].
+** The P and X arguments are pointers whose meanings depend on T.
+**
+** <dl>
+** [[SQLITE_TRACE_STMT]] <dt>SQLITE_TRACE_STMT</dt>
+** <dd>^An SQLITE_TRACE_STMT callback is invoked when a prepared statement
+** first begins running and possibly at other times during the
+** execution of the prepared statement, such as at the start of each
+** trigger subprogram. ^The P argument is a pointer to the
+** [prepared statement]. ^The X argument is a pointer to a string which
+** is the unexpanded SQL text of the prepared statement or an SQL comment 
+** that indicates the invocation of a trigger.  ^The callback can compute
+** the same text that would have been returned by the legacy [sqlite3_trace()]
+** interface by using the X argument when X begins with "--" and invoking
+** [sqlite3_expanded_sql(P)] otherwise.
+**
+** [[SQLITE_TRACE_PROFILE]] <dt>SQLITE_TRACE_PROFILE</dt>
+** <dd>^An SQLITE_TRACE_PROFILE callback provides approximately the same
+** information as is provided by the [sqlite3_profile()] callback.
+** ^The P argument is a pointer to the [prepared statement] and the
+** X argument points to a 64-bit integer which is the estimated of
+** the number of nanosecond that the prepared statement took to run.
+** ^The SQLITE_TRACE_PROFILE callback is invoked when the statement finishes.
+**
+** [[SQLITE_TRACE_ROW]] <dt>SQLITE_TRACE_ROW</dt>
+** <dd>^An SQLITE_TRACE_ROW callback is invoked whenever a prepared
+** statement generates a single row of result.  
+** ^The P argument is a pointer to the [prepared statement] and the
+** X argument is unused.
+**
+** [[SQLITE_TRACE_CLOSE]] <dt>SQLITE_TRACE_CLOSE</dt>
+** <dd>^An SQLITE_TRACE_CLOSE callback is invoked when a database
+** connection closes.
+** ^The P argument is a pointer to the [database connection] object
+** and the X argument is unused.
+** </dl>
+*/
+#define SQLITE_TRACE_STMT       0x01
+#define SQLITE_TRACE_PROFILE    0x02
+#define SQLITE_TRACE_ROW        0x04
+#define SQLITE_TRACE_CLOSE      0x08
+
+/*
+** CAPI3REF: SQL Trace Hook
+** METHOD: sqlite3
+**
+** ^The sqlite3_trace_v2(D,M,X,P) interface registers a trace callback
+** function X against [database connection] D, using property mask M
+** and context pointer P.  ^If the X callback is
+** NULL or if the M mask is zero, then tracing is disabled.  The
+** M argument should be the bitwise OR-ed combination of
+** zero or more [SQLITE_TRACE] constants.
+**
+** ^Each call to either sqlite3_trace() or sqlite3_trace_v2() overrides 
+** (cancels) any prior calls to sqlite3_trace() or sqlite3_trace_v2().
+**
+** ^The X callback is invoked whenever any of the events identified by 
+** mask M occur.  ^The integer return value from the callback is currently
+** ignored, though this may change in future releases.  Callback
+** implementations should return zero to ensure future compatibility.
+**
+** ^A trace callback is invoked with four arguments: callback(T,C,P,X).
+** ^The T argument is one of the [SQLITE_TRACE]
+** constants to indicate why the callback was invoked.
+** ^The C argument is a copy of the context pointer.
+** The P and X arguments are pointers whose meanings depend on T.
+**
+** The sqlite3_trace_v2() interface is intended to replace the legacy
+** interfaces [sqlite3_trace()] and [sqlite3_profile()], both of which
+** are deprecated.
+*/
+int sqlite3_trace_v2(
+  sqlite3*,
+  unsigned uMask,
+  int(*xCallback)(unsigned,void*,void*,void*),
+  void *pCtx
+);
+
+/*
 ** CAPI3REF: Query Progress Callbacks
 ** METHOD: sqlite3
 **
@@ -3354,11 +3558,35 @@ int sqlite3_prepare16_v2(
 ** CAPI3REF: Retrieving Statement SQL
 ** METHOD: sqlite3_stmt
 **
-** ^This interface can be used to retrieve a saved copy of the original
-** SQL text used to create a [prepared statement] if that statement was
-** compiled using either [sqlite3_prepare_v2()] or [sqlite3_prepare16_v2()].
+** ^The sqlite3_sql(P) interface returns a pointer to a copy of the UTF-8
+** SQL text used to create [prepared statement] P if P was
+** created by either [sqlite3_prepare_v2()] or [sqlite3_prepare16_v2()].
+** ^The sqlite3_expanded_sql(P) interface returns a pointer to a UTF-8
+** string containing the SQL text of prepared statement P with
+** [bound parameters] expanded.
+**
+** ^(For example, if a prepared statement is created using the SQL
+** text "SELECT $abc,:xyz" and if parameter $abc is bound to integer 2345
+** and parameter :xyz is unbound, then sqlite3_sql() will return
+** the original string, "SELECT $abc,:xyz" but sqlite3_expanded_sql()
+** will return "SELECT 2345,NULL".)^
+**
+** ^The sqlite3_expanded_sql() interface returns NULL if insufficient memory
+** is available to hold the result, or if the result would exceed the
+** the maximum string length determined by the [SQLITE_LIMIT_LENGTH].
+**
+** ^The [SQLITE_TRACE_SIZE_LIMIT] compile-time option limits the size of
+** bound parameter expansions.  ^The [SQLITE_OMIT_TRACE] compile-time
+** option causes sqlite3_expanded_sql() to always return NULL.
+**
+** ^The string returned by sqlite3_sql(P) is managed by SQLite and is
+** automatically freed when the prepared statement is finalized.
+** ^The string returned by sqlite3_expanded_sql(P), on the other hand,
+** is obtained from [sqlite3_malloc()] and must be free by the application
+** by passing it to [sqlite3_free()].
 */
 const char *sqlite3_sql(sqlite3_stmt *pStmt);
+char *sqlite3_expanded_sql(sqlite3_stmt *pStmt);
 
 /*
 ** CAPI3REF: Determine If An SQL Statement Writes The Database
@@ -3389,6 +3617,10 @@ const char *sqlite3_sql(sqlite3_stmt *pStmt);
 ** sqlite3_stmt_readonly() to return true since, while those statements
 ** change the configuration of a database connection, they do not make 
 ** changes to the content of the database files on disk.
+** ^The sqlite3_stmt_readonly() interface returns true for [BEGIN] since
+** [BEGIN] merely sets internal flags, but the [BEGIN|BEGIN IMMEDIATE] and
+** [BEGIN|BEGIN EXCLUSIVE] commands do touch the database and so
+** sqlite3_stmt_readonly() returns false for those commands.
 */
 int sqlite3_stmt_readonly(sqlite3_stmt *pStmt);
 
@@ -3671,8 +3903,12 @@ int sqlite3_clear_bindings(sqlite3_stmt*);
 ** METHOD: sqlite3_stmt
 **
 ** ^Return the number of columns in the result set returned by the
-** [prepared statement]. ^This routine returns 0 if pStmt is an SQL
-** statement that does not return data (for example an [UPDATE]).
+** [prepared statement]. ^If this routine returns 0, that means the 
+** [prepared statement] returns no data (for example an [UPDATE]).
+** ^However, just because this routine returns a positive number does not
+** mean that one or more rows of data will be returned.  ^A SELECT statement
+** will always have a positive sqlite3_column_count() but depending on the
+** WHERE clause constraints and the table content, it might return no rows.
 **
 ** See also: [sqlite3_data_count()]
 */
@@ -3853,7 +4089,8 @@ const void *sqlite3_column_decltype16(sqlite3_stmt*,int);
 ** other than [SQLITE_ROW] before any subsequent invocation of
 ** sqlite3_step().  Failure to reset the prepared statement using 
 ** [sqlite3_reset()] would result in an [SQLITE_MISUSE] return from
-** sqlite3_step().  But after version 3.6.23.1, sqlite3_step() began
+** sqlite3_step().  But after [version 3.6.23.1] ([dateof:3.6.23.1],
+** sqlite3_step() began
 ** calling [sqlite3_reset()] automatically in this circumstance rather
 ** than returning [SQLITE_MISUSE].  This is not considered a compatibility
 ** break because any application that ever receives an SQLITE_MISUSE error
@@ -4516,12 +4753,13 @@ sqlite3 *sqlite3_context_db_handle(sqlite3_context*);
 ** SQLite will invoke the destructor function X with parameter P exactly
 ** once, when the metadata is discarded.
 ** SQLite is free to discard the metadata at any time, including: <ul>
-** <li> when the corresponding function parameter changes, or
-** <li> when [sqlite3_reset()] or [sqlite3_finalize()] is called for the
-**      SQL statement, or
-** <li> when sqlite3_set_auxdata() is invoked again on the same parameter, or
-** <li> during the original sqlite3_set_auxdata() call when a memory 
-**      allocation error occurs. </ul>)^
+** <li> ^(when the corresponding function parameter changes)^, or
+** <li> ^(when [sqlite3_reset()] or [sqlite3_finalize()] is called for the
+**      SQL statement)^, or
+** <li> ^(when sqlite3_set_auxdata() is invoked again on the same
+**       parameter)^, or
+** <li> ^(during the original sqlite3_set_auxdata() call when a memory 
+**      allocation error occurs.)^ </ul>
 **
 ** Note the last bullet in particular.  The destructor X in 
 ** sqlite3_set_auxdata(C,N,P,X) might be called immediately, before the
@@ -5158,7 +5396,7 @@ void *sqlite3_rollback_hook(sqlite3*, void(*)(void *), void*);
 ** ^The sqlite3_update_hook() interface registers a callback function
 ** with the [database connection] identified by the first argument
 ** to be invoked whenever a row is updated, inserted or deleted in
-** a rowid table.
+** a [rowid table].
 ** ^Any callback set by a previous call to this function
 ** for the same database connection is overridden.
 **
@@ -5179,7 +5417,7 @@ void *sqlite3_rollback_hook(sqlite3*, void(*)(void *), void*);
 ** ^The update hook is not invoked when [WITHOUT ROWID] tables are modified.
 **
 ** ^In the current implementation, the update hook
-** is not invoked when duplication rows are deleted because of an
+** is not invoked when conflicting rows are deleted because of an
 ** [ON CONFLICT | ON CONFLICT REPLACE] clause.  ^Nor is the update hook
 ** invoked when rows are deleted using the [truncate optimization].
 ** The exceptions defined in this paragraph might change in a future
@@ -5197,8 +5435,8 @@ void *sqlite3_rollback_hook(sqlite3*, void(*)(void *), void*);
 ** on the same [database connection] D, or NULL for
 ** the first call on D.
 **
-** See also the [sqlite3_commit_hook()] and [sqlite3_rollback_hook()]
-** interfaces.
+** See also the [sqlite3_commit_hook()], [sqlite3_rollback_hook()],
+** and [sqlite3_preupdate_hook()] interfaces.
 */
 void *sqlite3_update_hook(
   sqlite3*, 
@@ -5215,7 +5453,8 @@ void *sqlite3_update_hook(
 ** and disabled if the argument is false.)^
 **
 ** ^Cache sharing is enabled and disabled for an entire process.
-** This is a change as of SQLite version 3.5.0. In prior versions of SQLite,
+** This is a change as of SQLite [version 3.5.0] ([dateof:3.5.0]). 
+** In prior versions of SQLite,
 ** sharing was enabled or disabled for each thread separately.
 **
 ** ^(The cache sharing mode set by this interface effects all subsequent
@@ -5309,7 +5548,8 @@ int sqlite3_db_release_memory(sqlite3*);
 **      from the heap.
 ** </ul>)^
 **
-** Beginning with SQLite version 3.7.3, the soft heap limit is enforced
+** Beginning with SQLite [version 3.7.3] ([dateof:3.7.3]), 
+** the soft heap limit is enforced
 ** regardless of whether or not the [SQLITE_ENABLE_MEMORY_MANAGEMENT]
 ** compile-time option is invoked.  With [SQLITE_ENABLE_MEMORY_MANAGEMENT],
 ** the soft heap limit is enforced on every memory allocation.  Without
@@ -5348,7 +5588,7 @@ SQLITE_DEPRECATED void sqlite3_soft_heap_limit(int N);
 ** column exists.  ^The sqlite3_table_column_metadata() interface returns
 ** SQLITE_ERROR and if the specified column does not exist.
 ** ^If the column-name parameter to sqlite3_table_column_metadata() is a
-** NULL pointer, then this routine simply checks for the existance of the
+** NULL pointer, then this routine simply checks for the existence of the
 ** table and returns SQLITE_OK if the table exists and SQLITE_ERROR if it
 ** does not.
 **
@@ -5445,9 +5685,18 @@ int sqlite3_table_column_metadata(
 ** should free this memory by calling [sqlite3_free()].
 **
 ** ^Extension loading must be enabled using
-** [sqlite3_enable_load_extension()] prior to calling this API,
+** [sqlite3_enable_load_extension()] or
+** [sqlite3_db_config](db,[SQLITE_DBCONFIG_ENABLE_LOAD_EXTENSION],1,NULL)
+** prior to calling this API,
 ** otherwise an error will be returned.
 **
+** <b>Security warning:</b> It is recommended that the 
+** [SQLITE_DBCONFIG_ENABLE_LOAD_EXTENSION] method be used to enable only this
+** interface.  The use of the [sqlite3_enable_load_extension()] interface
+** should be avoided.  This will keep the SQL function [load_extension()]
+** disabled and prevent SQL injections from giving attackers
+** access to extension loading capabilities.
+**
 ** See also the [load_extension() SQL function].
 */
 int sqlite3_load_extension(
@@ -5470,6 +5719,17 @@ int sqlite3_load_extension(
 ** ^Call the sqlite3_enable_load_extension() routine with onoff==1
 ** to turn extension loading on and call it with onoff==0 to turn
 ** it back off again.
+**
+** ^This interface enables or disables both the C-API
+** [sqlite3_load_extension()] and the SQL function [load_extension()].
+** ^(Use [sqlite3_db_config](db,[SQLITE_DBCONFIG_ENABLE_LOAD_EXTENSION],..)
+** to enable or disable only the C-API.)^
+**
+** <b>Security warning:</b> It is recommended that extension loading
+** be disabled using the [SQLITE_DBCONFIG_ENABLE_LOAD_EXTENSION] method
+** rather than this interface, so the [load_extension()] SQL function
+** remains disabled. This will prevent SQL injections from giving attackers
+** access to extension loading capabilities.
 */
 int sqlite3_enable_load_extension(sqlite3 *db, int onoff);
 
@@ -5483,7 +5743,7 @@ int sqlite3_enable_load_extension(sqlite3 *db, int onoff);
 **
 ** ^(Even though the function prototype shows that xEntryPoint() takes
 ** no arguments and returns void, SQLite invokes xEntryPoint() with three
-** arguments and expects and integer result as if the signature of the
+** arguments and expects an integer result as if the signature of the
 ** entry point where as follows:
 **
 ** <blockquote><pre>
@@ -5509,7 +5769,7 @@ int sqlite3_enable_load_extension(sqlite3 *db, int onoff);
 ** See also: [sqlite3_reset_auto_extension()]
 ** and [sqlite3_cancel_auto_extension()]
 */
-int sqlite3_auto_extension(void (*xEntryPoint)(void));
+int sqlite3_auto_extension(void(*xEntryPoint)(void));
 
 /*
 ** CAPI3REF: Cancel Automatic Extension Loading
@@ -5521,7 +5781,7 @@ int sqlite3_auto_extension(void (*xEntryPoint)(void));
 ** unregistered and it returns 0 if X was not on the list of initialization
 ** routines.
 */
-int sqlite3_cancel_auto_extension(void (*xEntryPoint)(void));
+int sqlite3_cancel_auto_extension(void(*xEntryPoint)(void));
 
 /*
 ** CAPI3REF: Reset Automatic Extension Loading
@@ -5683,13 +5943,15 @@ struct sqlite3_module {
 ** the xUpdate method are automatically rolled back by SQLite.
 **
 ** IMPORTANT: The estimatedRows field was added to the sqlite3_index_info
-** structure for SQLite version 3.8.2. If a virtual table extension is
+** structure for SQLite [version 3.8.2] ([dateof:3.8.2]). 
+** If a virtual table extension is
 ** used with an SQLite version earlier than 3.8.2, the results of attempting 
 ** to read or write the estimatedRows field are undefined (but are likely 
 ** to included crashing the application). The estimatedRows field should
 ** therefore only be used if [sqlite3_libversion_number()] returns a
 ** value greater than or equal to 3008002. Similarly, the idxFlags field
-** was added for version 3.9.0. It may therefore only be used if
+** was added for [version 3.9.0] ([dateof:3.9.0]). 
+** It may therefore only be used if
 ** sqlite3_libversion_number() returns a value greater than or equal to
 ** 3009000.
 */
@@ -5697,7 +5959,7 @@ struct sqlite3_index_info {
   /* Inputs */
   int nConstraint;           /* Number of entries in aConstraint */
   struct sqlite3_index_constraint {
-     int iColumn;              /* Column on left-hand side of constraint */
+     int iColumn;              /* Column constrained.  -1 for ROWID */
      unsigned char op;         /* Constraint operator */
      unsigned char usable;     /* True if this constraint is usable */
      int iTermOffset;          /* Used internally - xBestIndex should ignore */
@@ -5937,6 +6199,12 @@ typedef struct sqlite3_blob sqlite3_blob;
 ** [database connection] error code and message accessible via 
 ** [sqlite3_errcode()] and [sqlite3_errmsg()] and related functions. 
 **
+** A BLOB referenced by sqlite3_blob_open() may be read using the
+** [sqlite3_blob_read()] interface and modified by using
+** [sqlite3_blob_write()].  The [BLOB handle] can be moved to a
+** different row of the same table using the [sqlite3_blob_reopen()]
+** interface.  However, the column, table, or database of a [BLOB handle]
+** cannot be changed after the [BLOB handle] is opened.
 **
 ** ^(If the row that a BLOB handle points to is modified by an
 ** [UPDATE], [DELETE], or by [ON CONFLICT] side-effects
@@ -5960,6 +6228,10 @@ typedef struct sqlite3_blob sqlite3_blob;
 **
 ** To avoid a resource leak, every open [BLOB handle] should eventually
 ** be released by a call to [sqlite3_blob_close()].
+**
+** See also: [sqlite3_blob_close()],
+** [sqlite3_blob_reopen()], [sqlite3_blob_read()],
+** [sqlite3_blob_bytes()], [sqlite3_blob_write()].
 */
 int sqlite3_blob_open(
   sqlite3*,
@@ -5975,11 +6247,11 @@ int sqlite3_blob_open(
 ** CAPI3REF: Move a BLOB Handle to a New Row
 ** METHOD: sqlite3_blob
 **
-** ^This function is used to move an existing blob handle so that it points
+** ^This function is used to move an existing [BLOB handle] so that it points
 ** to a different row of the same database table. ^The new row is identified
 ** by the rowid value passed as the second argument. Only the row can be
 ** changed. ^The database, table and column on which the blob handle is open
-** remain the same. Moving an existing blob handle to a new row can be
+** remain the same. Moving an existing [BLOB handle] to a new row is
 ** faster than closing the existing handle and opening a new one.
 **
 ** ^(The new row must meet the same criteria as for [sqlite3_blob_open()] -
@@ -6387,7 +6659,7 @@ int sqlite3_mutex_notheld(sqlite3_mutex*);
 #define SQLITE_MUTEX_STATIC_MEM       3  /* sqlite3_malloc() */
 #define SQLITE_MUTEX_STATIC_MEM2      4  /* NOT USED */
 #define SQLITE_MUTEX_STATIC_OPEN      4  /* sqlite3BtreeOpen() */
-#define SQLITE_MUTEX_STATIC_PRNG      5  /* sqlite3_random() */
+#define SQLITE_MUTEX_STATIC_PRNG      5  /* sqlite3_randomness() */
 #define SQLITE_MUTEX_STATIC_LRU       6  /* lru page list */
 #define SQLITE_MUTEX_STATIC_LRU2      7  /* NOT USED */
 #define SQLITE_MUTEX_STATIC_PMEM      7  /* sqlite3PageMalloc() */
@@ -6491,6 +6763,7 @@ int sqlite3_test_control(int op, ...);
 #define SQLITE_TESTCTRL_SCRATCHMALLOC           17
 #define SQLITE_TESTCTRL_LOCALTIME_FAULT         18
 #define SQLITE_TESTCTRL_EXPLAIN_STMT            19  /* NOT USED */
+#define SQLITE_TESTCTRL_ONCE_RESET_THRESHOLD    19
 #define SQLITE_TESTCTRL_NEVER_CORRUPT           20
 #define SQLITE_TESTCTRL_VDBE_COVERAGE           21
 #define SQLITE_TESTCTRL_BYTEORDER               22
@@ -6697,6 +6970,18 @@ int sqlite3_db_status(sqlite3*, int op, int *pCur, int *pHiwtr, int resetFlg);
 ** memory used by all pager caches associated with the database connection.)^
 ** ^The highwater mark associated with SQLITE_DBSTATUS_CACHE_USED is always 0.
 **
+** [[SQLITE_DBSTATUS_CACHE_USED_SHARED]] 
+** ^(<dt>SQLITE_DBSTATUS_CACHE_USED_SHARED</dt>
+** <dd>This parameter is similar to DBSTATUS_CACHE_USED, except that if a
+** pager cache is shared between two or more connections the bytes of heap
+** memory used by that pager cache is divided evenly between the attached
+** connections.)^  In other words, if none of the pager caches associated
+** with the database connection are shared, this request returns the same
+** value as DBSTATUS_CACHE_USED. Or, if one or more or the pager caches are
+** shared, the value returned by this call will be smaller than that returned
+** by DBSTATUS_CACHE_USED. ^The highwater mark associated with
+** SQLITE_DBSTATUS_CACHE_USED_SHARED is always 0.
+**
 ** [[SQLITE_DBSTATUS_SCHEMA_USED]] ^(<dt>SQLITE_DBSTATUS_SCHEMA_USED</dt>
 ** <dd>This parameter returns the approximate number of bytes of heap
 ** memory used to store the schema for all databases associated
@@ -6754,7 +7039,8 @@ int sqlite3_db_status(sqlite3*, int op, int *pCur, int *pHiwtr, int resetFlg);
 #define SQLITE_DBSTATUS_CACHE_MISS           8
 #define SQLITE_DBSTATUS_CACHE_WRITE          9
 #define SQLITE_DBSTATUS_DEFERRED_FKS        10
-#define SQLITE_DBSTATUS_MAX                 10   /* Largest defined DBSTATUS */
+#define SQLITE_DBSTATUS_CACHE_USED_SHARED   11
+#define SQLITE_DBSTATUS_MAX                 11   /* Largest defined DBSTATUS */
 
 
 /*
@@ -7108,7 +7394,7 @@ typedef struct sqlite3_backup sqlite3_backup;
 ** must be different or else sqlite3_backup_init(D,N,S,M) will fail with
 ** an error.
 **
-** ^A call to sqlite3_backup_init() will fail, returning SQLITE_ERROR, if 
+** ^A call to sqlite3_backup_init() will fail, returning NULL, if 
 ** there is already a read or read-write transaction open on the 
 ** destination database.
 **
@@ -7512,7 +7798,7 @@ void sqlite3_log(int iErrCode, const char *zFormat, ...);
 ** previously registered write-ahead log callback. ^Note that the
 ** [sqlite3_wal_autocheckpoint()] interface and the
 ** [wal_autocheckpoint pragma] both invoke [sqlite3_wal_hook()] and will
-** those overwrite any prior [sqlite3_wal_hook()] settings.
+** overwrite any prior [sqlite3_wal_hook()] settings.
 */
 void *sqlite3_wal_hook(
   sqlite3*, 
@@ -7910,8 +8196,122 @@ void sqlite3_stmt_scanstatus_reset(sqlite3_stmt*);
 int sqlite3_db_cacheflush(sqlite3*);
 
 /*
+** CAPI3REF: The pre-update hook.
+**
+** ^These interfaces are only available if SQLite is compiled using the
+** [SQLITE_ENABLE_PREUPDATE_HOOK] compile-time option.
+**
+** ^The [sqlite3_preupdate_hook()] interface registers a callback function
+** that is invoked prior to each [INSERT], [UPDATE], and [DELETE] operation
+** on a database table.
+** ^At most one preupdate hook may be registered at a time on a single
+** [database connection]; each call to [sqlite3_preupdate_hook()] overrides
+** the previous setting.
+** ^The preupdate hook is disabled by invoking [sqlite3_preupdate_hook()]
+** with a NULL pointer as the second parameter.
+** ^The third parameter to [sqlite3_preupdate_hook()] is passed through as
+** the first parameter to callbacks.
+**
+** ^The preupdate hook only fires for changes to real database tables; the
+** preupdate hook is not invoked for changes to [virtual tables] or to
+** system tables like sqlite_master or sqlite_stat1.
+**
+** ^The second parameter to the preupdate callback is a pointer to
+** the [database connection] that registered the preupdate hook.
+** ^The third parameter to the preupdate callback is one of the constants
+** [SQLITE_INSERT], [SQLITE_DELETE], or [SQLITE_UPDATE] to identify the
+** kind of update operation that is about to occur.
+** ^(The fourth parameter to the preupdate callback is the name of the
+** database within the database connection that is being modified.  This
+** will be "main" for the main database or "temp" for TEMP tables or 
+** the name given after the AS keyword in the [ATTACH] statement for attached
+** databases.)^
+** ^The fifth parameter to the preupdate callback is the name of the
+** table that is being modified.
+**
+** For an UPDATE or DELETE operation on a [rowid table], the sixth
+** parameter passed to the preupdate callback is the initial [rowid] of the 
+** row being modified or deleted. For an INSERT operation on a rowid table,
+** or any operation on a WITHOUT ROWID table, the value of the sixth 
+** parameter is undefined. For an INSERT or UPDATE on a rowid table the
+** seventh parameter is the final rowid value of the row being inserted
+** or updated. The value of the seventh parameter passed to the callback
+** function is not defined for operations on WITHOUT ROWID tables, or for
+** INSERT operations on rowid tables.
+**
+** The [sqlite3_preupdate_old()], [sqlite3_preupdate_new()],
+** [sqlite3_preupdate_count()], and [sqlite3_preupdate_depth()] interfaces
+** provide additional information about a preupdate event. These routines
+** may only be called from within a preupdate callback.  Invoking any of
+** these routines from outside of a preupdate callback or with a
+** [database connection] pointer that is different from the one supplied
+** to the preupdate callback results in undefined and probably undesirable
+** behavior.
+**
+** ^The [sqlite3_preupdate_count(D)] interface returns the number of columns
+** in the row that is being inserted, updated, or deleted.
+**
+** ^The [sqlite3_preupdate_old(D,N,P)] interface writes into P a pointer to
+** a [protected sqlite3_value] that contains the value of the Nth column of
+** the table row before it is updated.  The N parameter must be between 0
+** and one less than the number of columns or the behavior will be
+** undefined. This must only be used within SQLITE_UPDATE and SQLITE_DELETE
+** preupdate callbacks; if it is used by an SQLITE_INSERT callback then the
+** behavior is undefined.  The [sqlite3_value] that P points to
+** will be destroyed when the preupdate callback returns.
+**
+** ^The [sqlite3_preupdate_new(D,N,P)] interface writes into P a pointer to
+** a [protected sqlite3_value] that contains the value of the Nth column of
+** the table row after it is updated.  The N parameter must be between 0
+** and one less than the number of columns or the behavior will be
+** undefined. This must only be used within SQLITE_INSERT and SQLITE_UPDATE
+** preupdate callbacks; if it is used by an SQLITE_DELETE callback then the
+** behavior is undefined.  The [sqlite3_value] that P points to
+** will be destroyed when the preupdate callback returns.
+**
+** ^The [sqlite3_preupdate_depth(D)] interface returns 0 if the preupdate
+** callback was invoked as a result of a direct insert, update, or delete
+** operation; or 1 for inserts, updates, or deletes invoked by top-level 
+** triggers; or 2 for changes resulting from triggers called by top-level
+** triggers; and so forth.
+**
+** See also:  [sqlite3_update_hook()]
+*/
+#if defined(SQLITE_ENABLE_PREUPDATE_HOOK)
+void *sqlite3_preupdate_hook(
+  sqlite3 *db,
+  void(*xPreUpdate)(
+    void *pCtx,                   /* Copy of third arg to preupdate_hook() */
+    sqlite3 *db,                  /* Database handle */
+    int op,                       /* SQLITE_UPDATE, DELETE or INSERT */
+    char const *zDb,              /* Database name */
+    char const *zName,            /* Table name */
+    sqlite3_int64 iKey1,          /* Rowid of row about to be deleted/updated */
+    sqlite3_int64 iKey2           /* New rowid value (for a rowid UPDATE) */
+  ),
+  void*
+);
+int sqlite3_preupdate_old(sqlite3 *, int, sqlite3_value **);
+int sqlite3_preupdate_count(sqlite3 *);
+int sqlite3_preupdate_depth(sqlite3 *);
+int sqlite3_preupdate_new(sqlite3 *, int, sqlite3_value **);
+#endif
+
+/*
+** CAPI3REF: Low-level system error code
+**
+** ^Attempt to return the underlying operating system error code or error
+** number that caused the most recent I/O error or failure to open a file.
+** The return value is OS-dependent.  For example, on unix systems, after
+** [sqlite3_open_v2()] returns [SQLITE_CANTOPEN], this interface could be
+** called to get back the underlying "errno" that caused the problem, such
+** as ENOSPC, EAUTH, EISDIR, and so forth.  
+*/
+int sqlite3_system_errno(sqlite3*);
+
+/*
 ** CAPI3REF: Database Snapshot
-** KEYWORDS: {snapshot}
+** KEYWORDS: {snapshot} {sqlite3_snapshot}
 ** EXPERIMENTAL
 **
 ** An instance of the snapshot object records the state of a [WAL mode]
@@ -7935,7 +8335,9 @@ int sqlite3_db_cacheflush(sqlite3*);
 ** to an historical snapshot (if possible).  The destructor for 
 ** sqlite3_snapshot objects is [sqlite3_snapshot_free()].
 */
-typedef struct sqlite3_snapshot sqlite3_snapshot;
+typedef struct sqlite3_snapshot {
+  unsigned char hidden[48];
+} sqlite3_snapshot;
 
 /*
 ** CAPI3REF: Record A Database Snapshot
@@ -7946,9 +8348,32 @@ typedef struct sqlite3_snapshot sqlite3_snapshot;
 ** schema S in database connection D.  ^On success, the
 ** [sqlite3_snapshot_get(D,S,P)] interface writes a pointer to the newly
 ** created [sqlite3_snapshot] object into *P and returns SQLITE_OK.
-** ^If schema S of [database connection] D is not a [WAL mode] database
-** that is in a read transaction, then [sqlite3_snapshot_get(D,S,P)]
-** leaves the *P value unchanged and returns an appropriate [error code].
+** If there is not already a read-transaction open on schema S when
+** this function is called, one is opened automatically. 
+**
+** The following must be true for this function to succeed. If any of
+** the following statements are false when sqlite3_snapshot_get() is
+** called, SQLITE_ERROR is returned. The final value of *P is undefined
+** in this case. 
+**
+** <ul>
+**   <li> The database handle must be in [autocommit mode].
+**
+**   <li> Schema S of [database connection] D must be a [WAL mode] database.
+**
+**   <li> There must not be a write transaction open on schema S of database
+**        connection D.
+**
+**   <li> One or more transactions must have been written to the current wal
+**        file since it was created on disk (by any connection). This means
+**        that a snapshot cannot be taken on a wal mode database with no wal 
+**        file immediately after it is first opened. At least one transaction
+**        must be written to it first.
+** </ul>
+**
+** This function may also return SQLITE_NOMEM.  If it is called with the
+** database handle in autocommit mode but fails for some other reason, 
+** whether or not a read transaction is opened on schema S is undefined.
 **
 ** The [sqlite3_snapshot] object returned from a successful call to
 ** [sqlite3_snapshot_get()] must be freed using [sqlite3_snapshot_free()]
@@ -7967,17 +8392,30 @@ SQLITE_EXPERIMENTAL int sqlite3_snapshot_get(
 ** CAPI3REF: Start a read transaction on an historical snapshot
 ** EXPERIMENTAL
 **
-** ^The [sqlite3_snapshot_open(D,S,P)] interface attempts to move the
-** read transaction that is currently open on schema S of
-** [database connection] D so that it refers to historical [snapshot] P.
+** ^The [sqlite3_snapshot_open(D,S,P)] interface starts a
+** read transaction for schema S of
+** [database connection] D such that the read transaction
+** refers to historical [snapshot] P, rather than the most
+** recent change to the database.
 ** ^The [sqlite3_snapshot_open()] interface returns SQLITE_OK on success
 ** or an appropriate [error code] if it fails.
 **
 ** ^In order to succeed, a call to [sqlite3_snapshot_open(D,S,P)] must be
-** the first operation, apart from other sqlite3_snapshot_open() calls,
-** following the [BEGIN] that starts a new read transaction.
-** ^A [snapshot] will fail to open if it has been overwritten by a 
-** [checkpoint].  
+** the first operation following the [BEGIN] that takes the schema S
+** out of [autocommit mode].
+** ^In other words, schema S must not currently be in
+** a transaction for [sqlite3_snapshot_open(D,S,P)] to work, but the
+** database connection D must be out of [autocommit mode].
+** ^A [snapshot] will fail to open if it has been overwritten by a
+** [checkpoint].
+** ^(A call to [sqlite3_snapshot_open(D,S,P)] will fail if the
+** database connection D does not know that the database file for
+** schema S is in [WAL mode].  A database connection might not know
+** that the database file is in [WAL mode] if there has been no prior
+** I/O on that database connection, or if the database entered [WAL mode] 
+** after the most recent I/O on the database connection.)^
+** (Hint: Run "[PRAGMA application_id]" against a newly opened
+** database connection in order to make it ready to use snapshots.)
 **
 ** The [sqlite3_snapshot_open()] interface is only available when the
 ** SQLITE_ENABLE_SNAPSHOT compile-time option is used.
@@ -8002,6 +8440,55 @@ SQLITE_EXPERIMENTAL int sqlite3_snapshot_open(
 SQLITE_EXPERIMENTAL void sqlite3_snapshot_free(sqlite3_snapshot*);
 
 /*
+** CAPI3REF: Compare the ages of two snapshot handles.
+** EXPERIMENTAL
+**
+** The sqlite3_snapshot_cmp(P1, P2) interface is used to compare the ages
+** of two valid snapshot handles. 
+**
+** If the two snapshot handles are not associated with the same database 
+** file, the result of the comparison is undefined. 
+**
+** Additionally, the result of the comparison is only valid if both of the
+** snapshot handles were obtained by calling sqlite3_snapshot_get() since the
+** last time the wal file was deleted. The wal file is deleted when the
+** database is changed back to rollback mode or when the number of database
+** clients drops to zero. If either snapshot handle was obtained before the 
+** wal file was last deleted, the value returned by this function 
+** is undefined.
+**
+** Otherwise, this API returns a negative value if P1 refers to an older
+** snapshot than P2, zero if the two handles refer to the same database
+** snapshot, and a positive value if P1 is a newer snapshot than P2.
+*/
+SQLITE_EXPERIMENTAL int sqlite3_snapshot_cmp(
+  sqlite3_snapshot *p1,
+  sqlite3_snapshot *p2
+);
+
+/*
+** CAPI3REF: Recover snapshots from a wal file
+** EXPERIMENTAL
+**
+** If all connections disconnect from a database file but do not perform
+** a checkpoint, the existing wal file is opened along with the database
+** file the next time the database is opened. At this point it is only
+** possible to successfully call sqlite3_snapshot_open() to open the most
+** recent snapshot of the database (the one at the head of the wal file),
+** even though the wal file may contain other valid snapshots for which
+** clients have sqlite3_snapshot handles.
+**
+** This function attempts to scan the wal file associated with database zDb
+** of database handle db and make all valid snapshots available to
+** sqlite3_snapshot_open(). It is an error if there is already a read
+** transaction open on the database, or if the database is not a wal mode
+** database.
+**
+** SQLITE_OK is returned if successful, or an SQLite error code otherwise.
+*/
+SQLITE_EXPERIMENTAL int sqlite3_snapshot_recover(sqlite3 *db, const char *zDb);
+
+/*
 ** Undo the hack that converts floating point types to integer for
 ** builds on processors without floating point support.
 */
@@ -8012,4 +8499,4 @@ SQLITE_EXPERIMENTAL void sqlite3_snapshot_free(sqlite3_snapshot*);
 #ifdef __cplusplus
 }  /* End of the 'extern "C"' block */
 #endif
-#endif /* _SQLITE3_H_ */
+#endif /* SQLITE3_H */