sqllogictest

** been edited in any way since it was last checked in, then the last
** four hexadecimal digits of the hash may be modified.
**
** See also: [sqlite3_libversion()],
** [sqlite3_libversion_number()], [sqlite3_sourceid()],
** [sqlite_version()] and [sqlite_source_id()].
*/
#define SQLITE_VERSION        "3.25.0"
#define SQLITE_VERSION_NUMBER 3025000
#define SQLITE_SOURCE_ID      "2018-09-12 08:51:48 572de7e4e33562c72cd90790b267ba389370f21ddcaebc4db609fd76ae9b7ada"

/*
** CAPI3REF: Run-Time Library Version Numbers
** 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

** on a per database connection basis using the
** [sqlite3_extended_result_codes()] API.  Or, the extended code for
** the most recent error can be obtained using
** [sqlite3_extended_errcode()].
*/
#define SQLITE_ERROR_MISSING_COLLSEQ   (SQLITE_ERROR | (1<<8))
#define SQLITE_ERROR_RETRY             (SQLITE_ERROR | (2<<8))
#define SQLITE_ERROR_SNAPSHOT          (SQLITE_ERROR | (3<<8))
#define SQLITE_IOERR_READ              (SQLITE_IOERR | (1<<8))
#define SQLITE_IOERR_SHORT_READ        (SQLITE_IOERR | (2<<8))
#define SQLITE_IOERR_WRITE             (SQLITE_IOERR | (3<<8))
#define SQLITE_IOERR_FSYNC             (SQLITE_IOERR | (4<<8))
#define SQLITE_IOERR_DIR_FSYNC         (SQLITE_IOERR | (5<<8))
#define SQLITE_IOERR_TRUNCATE          (SQLITE_IOERR | (6<<8))
#define SQLITE_IOERR_FSTAT             (SQLITE_IOERR | (7<<8))

#define SQLITE_LOCKED_VTAB             (SQLITE_LOCKED |  (2<<8))
#define SQLITE_BUSY_RECOVERY           (SQLITE_BUSY   |  (1<<8))
#define SQLITE_BUSY_SNAPSHOT           (SQLITE_BUSY   |  (2<<8))
#define SQLITE_CANTOPEN_NOTEMPDIR      (SQLITE_CANTOPEN | (1<<8))
#define SQLITE_CANTOPEN_ISDIR          (SQLITE_CANTOPEN | (2<<8))
#define SQLITE_CANTOPEN_FULLPATH       (SQLITE_CANTOPEN | (3<<8))
#define SQLITE_CANTOPEN_CONVPATH       (SQLITE_CANTOPEN | (4<<8))
#define SQLITE_CANTOPEN_DIRTYWAL       (SQLITE_CANTOPEN | (5<<8)) /* Not Used */
#define SQLITE_CORRUPT_VTAB            (SQLITE_CORRUPT | (1<<8))
#define SQLITE_CORRUPT_SEQUENCE        (SQLITE_CORRUPT | (2<<8))
#define SQLITE_READONLY_RECOVERY       (SQLITE_READONLY | (1<<8))
#define SQLITE_READONLY_CANTLOCK       (SQLITE_READONLY | (2<<8))
#define SQLITE_READONLY_ROLLBACK       (SQLITE_READONLY | (3<<8))
#define SQLITE_READONLY_DBMOVED        (SQLITE_READONLY | (4<<8))
#define SQLITE_READONLY_CANTINIT       (SQLITE_READONLY | (5<<8))

** is not changed but instead the prior value of that setting is written
** into the array entry, allowing the current retry settings to be
** interrogated.  The zDbName parameter is ignored.
**
** <li>[[SQLITE_FCNTL_PERSIST_WAL]]
** ^The [SQLITE_FCNTL_PERSIST_WAL] opcode is used to set or query the
** persistent [WAL | Write Ahead Log] setting.  By default, the auxiliary
** write ahead log ([WAL file]) and shared memory
** files used for transaction control
** are automatically deleted when the latest connection to the database
** closes.  Setting persistent WAL mode causes those files to persist after
** close.  Persisting the files is useful when other processes that do not
** have write permission on the directory containing the database file want
** to read the database file, as the WAL and shared memory files must exist
** in order for the database to be readable.  The fourth parameter to
** [sqlite3_file_control()] for this opcode should be a pointer to an integer.

** a prior successful call to [SQLITE_FCNTL_BEGIN_ATOMIC_WRITE].
**
** <li>[[SQLITE_FCNTL_LOCK_TIMEOUT]]
** The [SQLITE_FCNTL_LOCK_TIMEOUT] opcode causes attempts to obtain
** a file lock using the xLock or xShmLock methods of the VFS to wait
** for up to M milliseconds before failing, where M is the single 
** unsigned integer parameter.
**
** <li>[[SQLITE_FCNTL_DATA_VERSION]]
** The [SQLITE_FCNTL_DATA_VERSION] opcode is used to detect changes to
** a database file.  The argument is a pointer to a 32-bit unsigned integer.
** The "data version" for the pager is written into the pointer.  The
** "data version" changes whenever any change occurs to the corresponding
** database file, either through SQL statements on the same database
** connection, or through transactions committed by separate database
** connections possibly in other processes. The [sqlite3_total_changes()]
** interface can be used to find if any database on the connection has changed,
** but that interface response to changes on TEMP as well as MAIN and does
** not provide a mechanism to detect changes to MAIN only.  Also, the
** [sqlite3_total_changes()] interface response to internal changes only and
** omits changes made by other database connections.  The
** [PRAGMA data_version] command provide a mechanism to detect changes to
** a single attached database that occur due to other database connections,
** but omits changes implemented by the database connection for which it is
** called.  This file control is the only mechanism to detect changes that
** happen either internally or externally on a single database.
** </ul>
*/
#define SQLITE_FCNTL_LOCKSTATE               1
#define SQLITE_FCNTL_GET_LOCKPROXYFILE       2
#define SQLITE_FCNTL_SET_LOCKPROXYFILE       3
#define SQLITE_FCNTL_LAST_ERRNO              4
#define SQLITE_FCNTL_SIZE_HINT               5

#define SQLITE_FCNTL_JOURNAL_POINTER        28
#define SQLITE_FCNTL_WIN32_GET_HANDLE       29
#define SQLITE_FCNTL_PDB                    30
#define SQLITE_FCNTL_BEGIN_ATOMIC_WRITE     31
#define SQLITE_FCNTL_COMMIT_ATOMIC_WRITE    32
#define SQLITE_FCNTL_ROLLBACK_ATOMIC_WRITE  33
#define SQLITE_FCNTL_LOCK_TIMEOUT           34
#define SQLITE_FCNTL_DATA_VERSION           35

/* deprecated names */
#define SQLITE_GET_LOCKPROXYFILE      SQLITE_FCNTL_GET_LOCKPROXYFILE
#define SQLITE_SET_LOCKPROXYFILE      SQLITE_FCNTL_SET_LOCKPROXYFILE
#define SQLITE_LAST_ERRNO             SQLITE_FCNTL_LAST_ERRNO

**
** <dt>SQLITE_DBCONFIG_RESET_DATABASE</dt>
** <dd> Set the SQLITE_DBCONFIG_RESET_DATABASE flag and then run
** [VACUUM] in order to reset a database back to an empty database
** with no schema and no content. The following process works even for
** a badly corrupted database file:
** <ol>
** <li> If the database connection is newly opened, make sure it has read the
**      database schema by preparing then discarding some query against the
**      database, or calling sqlite3_table_column_metadata(), ignoring any
**      errors.  This step is only necessary if the application desires to keep
**      the database in WAL mode after the reset if it was in WAL mode before
**      the reset.  
** <li> sqlite3_db_config(db, SQLITE_DBCONFIG_RESET_DATABASE, 1, 0);
** <li> [sqlite3_exec](db, "[VACUUM]", 0, 0, 0);
** <li> sqlite3_db_config(db, SQLITE_DBCONFIG_RESET_DATABASE, 0, 0);
** </ol>
** Because resetting a database is destructive and irreversible, the
** process requires the use of this obscure API and multiple steps to help
** ensure that it does not happen by accident.

** ^This means that if the changes() SQL function (or similar) is used
** by the first INSERT, UPDATE or DELETE statement within a trigger, it 
** returns the value as set when the calling statement began executing.
** ^If it is used by the second or subsequent such statement within a trigger 
** program, the value returned reflects the number of rows modified by the 
** previous INSERT, UPDATE or DELETE statement within the same trigger.
**



** If a separate thread makes changes on the same database connection
** while [sqlite3_changes()] is running then the value returned
** is unpredictable and not meaningful.
**
** See also:
** <ul>
** <li> the [sqlite3_total_changes()] interface
** <li> the [count_changes pragma]
** <li> the [changes() SQL function]
** <li> the [data_version pragma]
** </ul>
*/
SQLITE_API int sqlite3_changes(sqlite3*);

/*
** CAPI3REF: Total Number Of Rows Modified
** METHOD: sqlite3
**
** ^This function returns the total number of rows inserted, modified or
** deleted by all [INSERT], [UPDATE] or [DELETE] statements completed
** since the database connection was opened, including those executed as
** part of trigger programs. ^Executing any other type of SQL statement
** does not affect the value returned by sqlite3_total_changes().
** 
** ^Changes made as part of [foreign key actions] are included in the
** count, but those made as part of REPLACE constraint resolution are
** not. ^Changes to a view that are intercepted by INSTEAD OF triggers 
** are not counted.
**
** This the [sqlite3_total_changes(D)] interface only reports the number
** of rows that changed due to SQL statement run against database
** connection D.  Any changes by other database connections are ignored.
** To detect changes against a database file from other database
** connections use the [PRAGMA data_version] command or the
** [SQLITE_FCNTL_DATA_VERSION] [file control].
** 
** If a separate thread makes changes on the same database connection
** while [sqlite3_total_changes()] is running then the value
** returned is unpredictable and not meaningful.
**
** See also:
** <ul>
** <li> the [sqlite3_changes()] interface
** <li> the [count_changes pragma]
** <li> the [changes() SQL function]
** <li> the [data_version pragma]
** <li> the [SQLITE_FCNTL_DATA_VERSION] [file control]
** </ul>
*/
SQLITE_API int sqlite3_total_changes(sqlite3*);

/*
** CAPI3REF: Interrupt A Long-Running Query
** METHOD: sqlite3
**

** CAPI3REF: Error Codes And Messages
** METHOD: sqlite3
**
** ^If the most recent sqlite3_* API call associated with 
** [database connection] D failed, then the sqlite3_errcode(D) interface
** returns the numeric [result code] or [extended result code] for that
** API call.


** ^The sqlite3_extended_errcode()
** interface is the same except that it always returns the 
** [extended result code] even when extended result codes are
** disabled.
**
** The values returned by sqlite3_errcode() and/or
** sqlite3_extended_errcode() might change with each API call.
** Except, there are some interfaces that are guaranteed to never
** change the value of the error code.  The error-code preserving
** interfaces are:
**
** <ul>
** <li> sqlite3_errcode()
** <li> sqlite3_extended_errcode()
** <li> sqlite3_errmsg()
** <li> sqlite3_errmsg16()
** </ul>
**
** ^The sqlite3_errmsg() and sqlite3_errmsg16() return English-language
** text that describes the error, as either UTF-8 or UTF-16 respectively.
** ^(Memory to hold the error message string is managed internally.
** The application does not need to worry about freeing the result.
** However, the error string might be overwritten or deallocated by
** subsequent calls to other SQLite interface functions.)^

** ^The pointers returned are valid until a type conversion occurs as
** described above, or until [sqlite3_step()] or [sqlite3_reset()] or
** [sqlite3_finalize()] is called.  ^The memory space used to hold strings
** and BLOBs is freed automatically.  Do not pass the pointers returned
** from [sqlite3_column_blob()], [sqlite3_column_text()], etc. into
** [sqlite3_free()].
**
** As long as the input parameters are correct, these routines will only
** fail if an out-of-memory error occurs during a format conversion.
** Only the following subset of interfaces are subject to out-of-memory
** errors:
**
** <ul>
** <li> sqlite3_column_blob()
** <li> sqlite3_column_text()
** <li> sqlite3_column_text16()
** <li> sqlite3_column_bytes()
** <li> sqlite3_column_bytes16()
** </ul>
**
** If an out-of-memory error occurs, then the return value from these
** routines is the same as if the column had contained an SQL NULL value.

** Valid SQL NULL returns can be distinguished from out-of-memory errors
** by invoking the [sqlite3_errcode()] immediately after the suspect
** return value is obtained and before any
** other SQLite interface is called on the same [database connection].
*/
SQLITE_API const void *sqlite3_column_blob(sqlite3_stmt*, int iCol);
SQLITE_API double sqlite3_column_double(sqlite3_stmt*, int iCol);
SQLITE_API int sqlite3_column_int(sqlite3_stmt*, int iCol);
SQLITE_API sqlite3_int64 sqlite3_column_int64(sqlite3_stmt*, int iCol);
SQLITE_API const unsigned char *sqlite3_column_text(sqlite3_stmt*, int iCol);
SQLITE_API const void *sqlite3_column_text16(sqlite3_stmt*, int iCol);

** KEYWORDS: {function creation routines}
** KEYWORDS: {application-defined SQL function}
** KEYWORDS: {application-defined SQL functions}
** METHOD: sqlite3
**
** ^These functions (collectively known as "function creation routines")
** are used to add SQL functions or aggregates or to redefine the behavior
** of existing SQL functions or aggregates. The only differences between
** the three "sqlite3_create_function*" routines are the text encoding 
** expected for the second parameter (the name of the function being 
** created) and the presence or absence of a destructor callback for
** the application data pointer. Function sqlite3_create_window_function()
** is similar, but allows the user to supply the extra callback functions
** needed by [aggregate window functions].
**
** ^The first parameter is the [database connection] to which the SQL
** function is to be added.  ^If an application uses more than one database
** connection then application-defined SQL functions must be added
** to each database connection separately.
**
** ^The second parameter is the name of the SQL function to be created or

** function that is not deterministic.  The SQLite query planner is able to
** perform additional optimizations on deterministic functions, so use
** of the [SQLITE_DETERMINISTIC] flag is recommended where possible.
**
** ^(The fifth parameter is an arbitrary pointer.  The implementation of the
** function can gain access to this pointer using [sqlite3_user_data()].)^
**
** ^The sixth, seventh and eighth parameters passed to the three
** "sqlite3_create_function*" functions, xFunc, xStep and xFinal, are
** pointers to C-language functions that implement the SQL function or
** aggregate. ^A scalar SQL function requires an implementation of the xFunc
** callback only; NULL pointers must be passed as the xStep and xFinal
** parameters. ^An aggregate SQL function requires an implementation of xStep
** and xFinal and NULL pointer must be passed for xFunc. ^To delete an existing
** SQL function or aggregate, pass NULL pointers for all three function
** callbacks.
**
** ^The sixth, seventh, eighth and ninth parameters (xStep, xFinal, xValue 
** and xInverse) passed to sqlite3_create_window_function are pointers to
** C-lanugage callbacks that implement the new function. xStep and xFinal
** must both be non-NULL. xValue and xInverse may either both be NULL, in
** which case a regular aggregate function is created, or must both be 
** non-NULL, in which case the new function may be used as either an aggregate
** or aggregate window function. More details regarding the implementation
** of aggregate window functions are 
** [user-defined window functions|available here].
**
** ^(If the final parameter to sqlite3_create_function_v2() or
** sqlite3_create_window_function() is not NULL, then it is destructor for
** the application data pointer. The destructor is invoked when the function 
** is deleted, either by being overloaded or when the database connection 
** closes.)^ ^The destructor is also invoked if the call to 
** sqlite3_create_function_v2() fails.  ^When the destructor callback is

** invoked, it is passed a single argument which is a copy of the application
** data pointer which was the fifth parameter to sqlite3_create_function_v2().
**
** ^It is permitted to register multiple implementations of the same
** functions with the same name but with either differing numbers of
** arguments or differing preferred text encodings.  ^SQLite will use
** the implementation that most closely matches the way in which the
** SQL function is used.  ^A function implementation with a non-negative
** nArg parameter is a better match than a function implementation with

  int nArg,
  int eTextRep,
  void *pApp,
  void (*xFunc)(sqlite3_context*,int,sqlite3_value**),
  void (*xStep)(sqlite3_context*,int,sqlite3_value**),
  void (*xFinal)(sqlite3_context*),
  void(*xDestroy)(void*)
);
SQLITE_API int sqlite3_create_window_function(
  sqlite3 *db,
  const char *zFunctionName,
  int nArg,
  int eTextRep,
  void *pApp,
  void (*xStep)(sqlite3_context*,int,sqlite3_value**),
  void (*xFinal)(sqlite3_context*),
  void (*xValue)(sqlite3_context*),
  void (*xInverse)(sqlite3_context*,int,sqlite3_value**),
  void(*xDestroy)(void*)
);

/*
** CAPI3REF: Text Encodings
**
** These constant define integer codes that represent the various
** text encodings supported by SQLite.

** from [sqlite3_value_blob()], [sqlite3_value_text()], or
** [sqlite3_value_text16()] can be invalidated by a subsequent call to
** [sqlite3_value_bytes()], [sqlite3_value_bytes16()], [sqlite3_value_text()],
** or [sqlite3_value_text16()].
**
** These routines must be called from the same thread as
** the SQL function that supplied the [sqlite3_value*] parameters.
**
** As long as the input parameter is correct, these routines can only
** fail if an out-of-memory error occurs during a format conversion.
** Only the following subset of interfaces are subject to out-of-memory
** errors:
**
** <ul>
** <li> sqlite3_value_blob()
** <li> sqlite3_value_text()
** <li> sqlite3_value_text16()
** <li> sqlite3_value_text16le()
** <li> sqlite3_value_text16be()
** <li> sqlite3_value_bytes()
** <li> sqlite3_value_bytes16()
** </ul>
**
** If an out-of-memory error occurs, then the return value from these
** routines is the same as if the column had contained an SQL NULL value.
** Valid SQL NULL returns can be distinguished from out-of-memory errors
** by invoking the [sqlite3_errcode()] immediately after the suspect
** return value is obtained and before any
** other SQLite interface is called on the same [database connection].
*/
SQLITE_API const void *sqlite3_value_blob(sqlite3_value*);
SQLITE_API double sqlite3_value_double(sqlite3_value*);
SQLITE_API int sqlite3_value_int(sqlite3_value*);
SQLITE_API sqlite3_int64 sqlite3_value_int64(sqlite3_value*);
SQLITE_API void *sqlite3_value_pointer(sqlite3_value*, const char*);
SQLITE_API const unsigned char *sqlite3_value_text(sqlite3_value*);

#define SQLITE_INDEX_CONSTRAINT_GLOB      66
#define SQLITE_INDEX_CONSTRAINT_REGEXP    67
#define SQLITE_INDEX_CONSTRAINT_NE        68
#define SQLITE_INDEX_CONSTRAINT_ISNOT     69
#define SQLITE_INDEX_CONSTRAINT_ISNOTNULL 70
#define SQLITE_INDEX_CONSTRAINT_ISNULL    71
#define SQLITE_INDEX_CONSTRAINT_IS        72
#define SQLITE_INDEX_CONSTRAINT_FUNCTION 150

/*
** CAPI3REF: Register A Virtual Table Implementation
** METHOD: sqlite3
**
** ^These routines are used to register a new [virtual table module] name.
** ^Module names must be registered before

** routine returns a NULL pointer.
*/
SQLITE_API sqlite3_mutex *sqlite3_db_mutex(sqlite3*);

/*
** CAPI3REF: Low-Level Control Of Database Files
** METHOD: sqlite3
** KEYWORDS: {file control}
**
** ^The [sqlite3_file_control()] interface makes a direct call to the
** xFileControl method for the [sqlite3_io_methods] object associated
** with a particular database identified by the second argument. ^The
** name of the database is "main" for the main database or "temp" for the
** TEMP database, or the name that appears after the AS keyword for
** databases that are added using the [ATTACH] SQL command.
** ^A NULL pointer can be used in place of "main" to refer to the
** main database file.
** ^The third and fourth parameters to this routine
** are passed directly through to the second and third parameters of
** the xFileControl method.  ^The return value of the xFileControl
** method becomes the return value of this routine.
**
** A few opcodes for [sqlite3_file_control()] are handled directly
** by the SQLite core and never invoke the 
** sqlite3_io_methods.xFileControl method.
** ^The [SQLITE_FCNTL_FILE_POINTER] value for the op parameter causes
** a pointer to the underlying [sqlite3_file] object to be written into
** the space pointed to by the 4th parameter.  The

** [SQLITE_FCNTL_JOURNAL_POINTER] works similarly except that it returns
** the [sqlite3_file] object associated with the journal file instead of
** the main database.  The [SQLITE_FCNTL_VFS_POINTER] opcode returns
** a pointer to the underlying [sqlite3_vfs] object for the file.
** The [SQLITE_FCNTL_DATA_VERSION] returns the data version counter
** from the pager.
**
** ^If the second parameter (zDbName) does not match the name of any
** open database file, then SQLITE_ERROR is returned.  ^This error
** code is not remembered and will not be recalled by [sqlite3_errcode()]
** or [sqlite3_errmsg()].  The underlying xFileControl method might
** also return SQLITE_ERROR.  There is no way to distinguish between
** an incorrect zDbName and an SQLITE_ERROR return from the underlying

** as ENOSPC, EAUTH, EISDIR, and so forth.  
*/
SQLITE_API int sqlite3_system_errno(sqlite3*);

/*
** CAPI3REF: Database Snapshot
** KEYWORDS: {snapshot} {sqlite3_snapshot}

**
** An instance of the snapshot object records the state of a [WAL mode]
** database for some specific point in history.
**
** In [WAL mode], multiple [database connections] that are open on the
** same database file can each be reading a different historical version
** of the database file.  When a [database connection] begins a read
** transaction, that connection sees an unchanging copy of the database
** as it existed for the point in time when the transaction first started.
** Subsequent changes to the database from other connections are not seen
** by the reader until a new read transaction is started.
**
** The sqlite3_snapshot object records state information about an historical
** version of the database file so that it is possible to later open a new read
** transaction that sees that historical version of the database rather than
** the most recent version.





*/
typedef struct sqlite3_snapshot {
  unsigned char hidden[48];
} sqlite3_snapshot;

/*
** CAPI3REF: Record A Database Snapshot
** CONSTRUCTOR: sqlite3_snapshot
**
** ^The [sqlite3_snapshot_get(D,S,P)] interface attempts to make a
** new [sqlite3_snapshot] object that records the current state of
** 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 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 not 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

** 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()]
** to avoid a memory leak.
**
** The [sqlite3_snapshot_get()] interface is only available when the
** [SQLITE_ENABLE_SNAPSHOT] compile-time option is used.
*/
SQLITE_API SQLITE_EXPERIMENTAL int sqlite3_snapshot_get(
  sqlite3 *db,
  const char *zSchema,
  sqlite3_snapshot **ppSnapshot
);

/*
** CAPI3REF: Start a read transaction on an historical snapshot
** METHOD: sqlite3_snapshot
**
** ^The [sqlite3_snapshot_open(D,S,P)] interface either starts a new read 
** transaction or upgrades an existing one 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, the database connection must not be in 

** [autocommit mode] when [sqlite3_snapshot_open(D,S,P)] is called. If there
** is already a read transaction open on schema S, then the database handle
** must have no active statements (SELECT statements that have been passed
** to sqlite3_step() but not sqlite3_reset() or sqlite3_finalize()). 
** SQLITE_ERROR is returned if either of these conditions is violated, or
** if schema S does not exist, or if the snapshot object is invalid.
**
** ^A call to sqlite3_snapshot_open() will fail to open if the specified

** snapshot has been overwritten by a [checkpoint]. In this case 
** SQLITE_ERROR_SNAPSHOT is returned.
**
** If there is already a read transaction open when this function is 
** invoked, then the same read transaction remains open (on the same
** database snapshot) if SQLITE_ERROR, SQLITE_BUSY or SQLITE_ERROR_SNAPSHOT
** is returned. If another error code - for example SQLITE_PROTOCOL or an
** SQLITE_IOERR error code - is returned, then the final state of the
** read transaction is undefined. If SQLITE_OK is returned, then the 
** read transaction is now open on database snapshot P.
**
** ^(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.
*/
SQLITE_API SQLITE_EXPERIMENTAL int sqlite3_snapshot_open(
  sqlite3 *db,
  const char *zSchema,
  sqlite3_snapshot *pSnapshot
);

/*
** CAPI3REF: Destroy a snapshot
** DESTRUCTOR: sqlite3_snapshot
**
** ^The [sqlite3_snapshot_free(P)] interface destroys [sqlite3_snapshot] P.
** The application must eventually free every [sqlite3_snapshot] object
** using this routine to avoid a memory leak.
**
** The [sqlite3_snapshot_free()] interface is only available when the
** [SQLITE_ENABLE_SNAPSHOT] compile-time option is used.
*/
SQLITE_API SQLITE_EXPERIMENTAL void sqlite3_snapshot_free(sqlite3_snapshot*);

/*
** CAPI3REF: Compare the ages of two snapshot handles.
** METHOD: sqlite3_snapshot
**
** 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.
**
** This interface is only available if SQLite is compiled with the
** [SQLITE_ENABLE_SNAPSHOT] option.
*/
SQLITE_API SQLITE_EXPERIMENTAL int sqlite3_snapshot_cmp(
  sqlite3_snapshot *p1,
  sqlite3_snapshot *p2
);

/*
** CAPI3REF: Recover snapshots from a wal file
** METHOD: sqlite3_snapshot
**
** If a [WAL file] remains on disk after all database connections close
** (either through the use of the [SQLITE_FCNTL_PERSIST_WAL] [file control]
** or because the last process to have the database opened exited without
** calling [sqlite3_close()]) and a new connection is subsequently opened
** on that database and [WAL file], the [sqlite3_snapshot_open()] interface

** will only be able to open the last transaction added to the WAL file
** even though the WAL file contains other valid transactions.

**
** 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.
**
** This interface is only available if SQLite is compiled with the
** [SQLITE_ENABLE_SNAPSHOT] option.
*/
SQLITE_API SQLITE_EXPERIMENTAL int sqlite3_snapshot_recover(sqlite3 *db, const char *zDb);

/*
** CAPI3REF: Serialize a database
**
** The sqlite3_serialize(D,S,P,F) interface returns a pointer to memory

** to the contiguous memory representation of the database that SQLite
** is currently using for that database, or NULL if the no such contiguous
** memory representation of the database exists.  A contiguous memory
** representation of the database will usually only exist if there has
** been a prior call to [sqlite3_deserialize(D,S,...)] with the same
** values of D and S.
** The size of the database is written into *P even if the 
** SQLITE_SERIALIZE_NOCOPY bit is set but no contiguous copy
** of the database exists.
**
** A call to sqlite3_serialize(D,S,P,F) might return NULL even if the
** SQLITE_SERIALIZE_NOCOPY bit is omitted from argument F if a memory
** allocation error occurs.
**
** This interface is only available if SQLite is compiled with the