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Comment:Add documentation to the sqlite3_preupdate_hook() interface and its relatives.
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SHA1: 8180f2881fa970429e28d4f3258a56cfaabbcabd
User & Date: drh 2011-03-30 17:07:47
Context
2011-03-30
17:25
Disable the truncate optimization if there is a preupdate hook. check-in: d051694e user: drh tags: sessions
17:07
Add documentation to the sqlite3_preupdate_hook() interface and its relatives. check-in: 8180f288 user: drh tags: sessions
02:03
Merge in all the latest changes from trunk. check-in: b11d941e user: drh tags: sessions
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Changes to src/sqlite.h.in.

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**
** The sqlite3_db_config() interface is used to make configuration
** changes to a [database connection].  The interface is similar to
** [sqlite3_config()] except that the changes apply to a single
** [database connection] (specified in the first argument).
**
** The second argument to sqlite3_db_config(D,V,...)  is the
** [SQLITE_DBCONIG_LOOKASIDE | configuration verb] - an integer code 
** that indicates what aspect of the [database connection] is being configured.
** Subsequent arguments vary depending on the configuration verb.
**
** ^Calls to sqlite3_db_config() return SQLITE_OK if and only if
** the call is considered successful.
*/
int sqlite3_db_config(sqlite3*, int op, ...);
................................................................................
** database connections for the meaning of "modify" in this paragraph.
**
** ^The sqlite3_update_hook(D,C,P) function
** returns the P argument from the previous call
** 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.
*/
void *sqlite3_update_hook(
  sqlite3*, 
  void(*)(void *,int ,char const *,char const *,sqlite3_int64),
  void*
);

................................................................................
#define SQLITE_CHECKPOINT_PASSIVE 0
#define SQLITE_CHECKPOINT_FULL    1
#define SQLITE_CHECKPOINT_RESTART 2


/*
** CAPI3REF: The pre-update hook.

** 
** The preupdate_old() API may only be used from within an SQLITE_UPDATE or
** SQLITE_DELETE pre-update callback. The preupdate_modified() API may only 
** be used from within an SQLITE_UPDATE pre-update callback.



































































*/
SQLITE_EXPERIMENTAL 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 */







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**
** The sqlite3_db_config() interface is used to make configuration
** changes to a [database connection].  The interface is similar to
** [sqlite3_config()] except that the changes apply to a single
** [database connection] (specified in the first argument).
**
** The second argument to sqlite3_db_config(D,V,...)  is the
** [SQLITE_DBCONFIG_LOOKASIDE | configuration verb] - an integer code 
** that indicates what aspect of the [database connection] is being configured.
** Subsequent arguments vary depending on the configuration verb.
**
** ^Calls to sqlite3_db_config() return SQLITE_OK if and only if
** the call is considered successful.
*/
int sqlite3_db_config(sqlite3*, int op, ...);
................................................................................
** database connections for the meaning of "modify" in this paragraph.
**
** ^The sqlite3_update_hook(D,C,P) function
** returns the P argument from the previous call
** on the same [database connection] D, or NULL for
** the first call on D.
**
** See also the [sqlite3_commit_hook()], [sqlite3_rollback_hook()],
** and [sqlite3_preupdate_hook()] interfaces.
*/
void *sqlite3_update_hook(
  sqlite3*, 
  void(*)(void *,int ,char const *,char const *,sqlite3_int64),
  void*
);

................................................................................
#define SQLITE_CHECKPOINT_PASSIVE 0
#define SQLITE_CHECKPOINT_FULL    1
#define SQLITE_CHECKPOINT_RESTART 2


/*
** CAPI3REF: The pre-update hook.
** EXPERIMENTAL
**

** ^The [sqlite3_preupdate_hook()] interface registers a callback function
** that is invoked prior to each [INSERT], [UPDATE], and [DELETE] operation.
** ^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 tables; the preupdate
** hook is not invoked for changes to virtual tables.
**
** ^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 indentify 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.
** ^The sixth parameter to the preupdate callback is the initial [rowid] of the
** row being changes for SQLITE_UPDATE and SQLITE_DELETE changes and is
** undefined for SQLITE_INSERT changes.
** ^The seventh parameter to the preupdate callback is the final [rowid] of
** the row being changed for SQLITE_UPDATE and SQLITE_INSERT changes and is
** undefined for SQLITE_DELETE changes.
**
** 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()]
*/
SQLITE_EXPERIMENTAL 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 */