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sqlite3session.h
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1277 lines (1234 loc) · 56.9 KB
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#ifndef __SQLITESESSION_H_
#define __SQLITESESSION_H_ 1
/*
** Make sure we can call this stuff from C++.
*/
#ifdef __cplusplus
extern "C" {
#endif
#include "sqlite3.h"
/*
** CAPI3REF: Session Object Handle
*/
typedef struct sqlite3_session sqlite3_session;
/*
** CAPI3REF: Changeset Iterator Handle
*/
typedef struct sqlite3_changeset_iter sqlite3_changeset_iter;
/*
** CAPI3REF: Create A New Session Object
**
** Create a new session object attached to database handle db. If successful,
** a pointer to the new object is written to *ppSession and SQLITE_OK is
** returned. If an error occurs, *ppSession is set to NULL and an SQLite
** error code (e.g. SQLITE_NOMEM) is returned.
**
** It is possible to create multiple session objects attached to a single
** database handle.
**
** Session objects created using this function should be deleted using the
** [sqlite3session_delete()] function before the database handle that they
** are attached to is itself closed. If the database handle is closed before
** the session object is deleted, then the results of calling any session
** module function, including [sqlite3session_delete()] on the session object
** are undefined.
**
** Because the session module uses the [sqlite3_preupdate_hook()] API, it
** is not possible for an application to register a pre-update hook on a
** database handle that has one or more session objects attached. Nor is
** it possible to create a session object attached to a database handle for
** which a pre-update hook is already defined. The results of attempting
** either of these things are undefined.
**
** The session object will be used to create changesets for tables in
** database zDb, where zDb is either "main", or "temp", or the name of an
** attached database. It is not an error if database zDb is not attached
** to the database when the session object is created.
*/
int sqlite3session_create(
sqlite3 *db, /* Database handle */
const char *zDb, /* Name of db (e.g. "main") */
sqlite3_session **ppSession /* OUT: New session object */
);
/*
** CAPI3REF: Delete A Session Object
**
** Delete a session object previously allocated using
** [sqlite3session_create()]. Once a session object has been deleted, the
** results of attempting to use pSession with any other session module
** function are undefined.
**
** Session objects must be deleted before the database handle to which they
** are attached is closed. Refer to the documentation for
** [sqlite3session_create()] for details.
*/
void sqlite3session_delete(sqlite3_session *pSession);
/*
** CAPI3REF: Enable Or Disable A Session Object
**
** Enable or disable the recording of changes by a session object. When
** enabled, a session object records changes made to the database. When
** disabled - it does not. A newly created session object is enabled.
** Refer to the documentation for [sqlite3session_changeset()] for further
** details regarding how enabling and disabling a session object affects
** the eventual changesets.
**
** Passing zero to this function disables the session. Passing a value
** greater than zero enables it. Passing a value less than zero is a
** no-op, and may be used to query the current state of the session.
**
** The return value indicates the final state of the session object: 0 if
** the session is disabled, or 1 if it is enabled.
*/
int sqlite3session_enable(sqlite3_session *pSession, int bEnable);
/*
** CAPI3REF: Set Or Clear the Indirect Change Flag
**
** Each change recorded by a session object is marked as either direct or
** indirect. A change is marked as indirect if either:
**
** <ul>
** <li> The session object "indirect" flag is set when the change is
** made, or
** <li> The change is made by an SQL trigger or foreign key action
** instead of directly as a result of a users SQL statement.
** </ul>
**
** If a single row is affected by more than one operation within a session,
** then the change is considered indirect if all operations meet the criteria
** for an indirect change above, or direct otherwise.
**
** This function is used to set, clear or query the session object indirect
** flag. If the second argument passed to this function is zero, then the
** indirect flag is cleared. If it is greater than zero, the indirect flag
** is set. Passing a value less than zero does not modify the current value
** of the indirect flag, and may be used to query the current state of the
** indirect flag for the specified session object.
**
** The return value indicates the final state of the indirect flag: 0 if
** it is clear, or 1 if it is set.
*/
int sqlite3session_indirect(sqlite3_session *pSession, int bIndirect);
/*
** CAPI3REF: Attach A Table To A Session Object
**
** If argument zTab is not NULL, then it is the name of a table to attach
** to the session object passed as the first argument. All subsequent changes
** made to the table while the session object is enabled will be recorded. See
** documentation for [sqlite3session_changeset()] for further details.
**
** Or, if argument zTab is NULL, then changes are recorded for all tables
** in the database. If additional tables are added to the database (by
** executing "CREATE TABLE" statements) after this call is made, changes for
** the new tables are also recorded.
**
** Changes can only be recorded for tables that have a PRIMARY KEY explicitly
** defined as part of their CREATE TABLE statement. It does not matter if the
** PRIMARY KEY is an "INTEGER PRIMARY KEY" (rowid alias) or not. The PRIMARY
** KEY may consist of a single column, or may be a composite key.
**
** It is not an error if the named table does not exist in the database. Nor
** is it an error if the named table does not have a PRIMARY KEY. However,
** no changes will be recorded in either of these scenarios.
**
** Changes are not recorded for individual rows that have NULL values stored
** in one or more of their PRIMARY KEY columns.
**
** SQLITE_OK is returned if the call completes without error. Or, if an error
** occurs, an SQLite error code (e.g. SQLITE_NOMEM) is returned.
*/
int sqlite3session_attach(
sqlite3_session *pSession, /* Session object */
const char *zTab /* Table name */
);
/*
** CAPI3REF: Set a table filter on a Session Object.
**
** The second argument (xFilter) is the "filter callback". For changes to rows
** in tables that are not attached to the Session oject, the filter is called
** to determine whether changes to the table's rows should be tracked or not.
** If xFilter returns 0, changes is not tracked. Note that once a table is
** attached, xFilter will not be called again.
*/
void sqlite3session_table_filter(
sqlite3_session *pSession, /* Session object */
int(*xFilter)(
void *pCtx, /* Copy of third arg to _filter_table() */
const char *zTab /* Table name */
),
void *pCtx /* First argument passed to xFilter */
);
/*
** CAPI3REF: Generate A Changeset From A Session Object
**
** Obtain a changeset containing changes to the tables attached to the
** session object passed as the first argument. If successful,
** set *ppChangeset to point to a buffer containing the changeset
** and *pnChangeset to the size of the changeset in bytes before returning
** SQLITE_OK. If an error occurs, set both *ppChangeset and *pnChangeset to
** zero and return an SQLite error code.
**
** A changeset consists of zero or more INSERT, UPDATE and/or DELETE changes,
** each representing a change to a single row of an attached table. An INSERT
** change contains the values of each field of a new database row. A DELETE
** contains the original values of each field of a deleted database row. An
** UPDATE change contains the original values of each field of an updated
** database row along with the updated values for each updated non-primary-key
** column. It is not possible for an UPDATE change to represent a change that
** modifies the values of primary key columns. If such a change is made, it
** is represented in a changeset as a DELETE followed by an INSERT.
**
** Changes are not recorded for rows that have NULL values stored in one or
** more of their PRIMARY KEY columns. If such a row is inserted or deleted,
** no corresponding change is present in the changesets returned by this
** function. If an existing row with one or more NULL values stored in
** PRIMARY KEY columns is updated so that all PRIMARY KEY columns are non-NULL,
** only an INSERT is appears in the changeset. Similarly, if an existing row
** with non-NULL PRIMARY KEY values is updated so that one or more of its
** PRIMARY KEY columns are set to NULL, the resulting changeset contains a
** DELETE change only.
**
** The contents of a changeset may be traversed using an iterator created
** using the [sqlite3changeset_start()] API. A changeset may be applied to
** a database with a compatible schema using the [sqlite3changeset_apply()]
** API.
**
** Within a changeset generated by this function, all changes related to a
** single table are grouped together. In other words, when iterating through
** a changeset or when applying a changeset to a database, all changes related
** to a single table are processed before moving on to the next table. Tables
** are sorted in the same order in which they were attached (or auto-attached)
** to the sqlite3_session object. The order in which the changes related to
** a single table are stored is undefined.
**
** Following a successful call to this function, it is the responsibility of
** the caller to eventually free the buffer that *ppChangeset points to using
** [sqlite3_free()].
**
** <h3>Changeset Generation</h3>
**
** Once a table has been attached to a session object, the session object
** records the primary key values of all new rows inserted into the table.
** It also records the original primary key and other column values of any
** deleted or updated rows. For each unique primary key value, data is only
** recorded once - the first time a row with said primary key is inserted,
** updated or deleted in the lifetime of the session.
**
** There is one exception to the previous paragraph: when a row is inserted,
** updated or deleted, if one or more of its primary key columns contain a
** NULL value, no record of the change is made.
**
** The session object therefore accumulates two types of records - those
** that consist of primary key values only (created when the user inserts
** a new record) and those that consist of the primary key values and the
** original values of other table columns (created when the users deletes
** or updates a record).
**
** When this function is called, the requested changeset is created using
** both the accumulated records and the current contents of the database
** file. Specifically:
**
** <ul>
** <li> For each record generated by an insert, the database is queried
** for a row with a matching primary key. If one is found, an INSERT
** change is added to the changeset. If no such row is found, no change
** is added to the changeset.
**
** <li> For each record generated by an update or delete, the database is
** queried for a row with a matching primary key. If such a row is
** found and one or more of the non-primary key fields have been
** modified from their original values, an UPDATE change is added to
** the changeset. Or, if no such row is found in the table, a DELETE
** change is added to the changeset. If there is a row with a matching
** primary key in the database, but all fields contain their original
** values, no change is added to the changeset.
** </ul>
**
** This means, amongst other things, that if a row is inserted and then later
** deleted while a session object is active, neither the insert nor the delete
** will be present in the changeset. Or if a row is deleted and then later a
** row with the same primary key values inserted while a session object is
** active, the resulting changeset will contain an UPDATE change instead of
** a DELETE and an INSERT.
**
** When a session object is disabled (see the [sqlite3session_enable()] API),
** it does not accumulate records when rows are inserted, updated or deleted.
** This may appear to have some counter-intuitive effects if a single row
** is written to more than once during a session. For example, if a row
** is inserted while a session object is enabled, then later deleted while
** the same session object is disabled, no INSERT record will appear in the
** changeset, even though the delete took place while the session was disabled.
** Or, if one field of a row is updated while a session is disabled, and
** another field of the same row is updated while the session is enabled, the
** resulting changeset will contain an UPDATE change that updates both fields.
*/
int sqlite3session_changeset(
sqlite3_session *pSession, /* Session object */
int *pnChangeset, /* OUT: Size of buffer at *ppChangeset */
void **ppChangeset /* OUT: Buffer containing changeset */
);
/*
** CAPI3REF: Load The Difference Between Tables Into A Session
**
** If it is not already attached to the session object passed as the first
** argument, this function attaches table zTbl in the same manner as the
** [sqlite3session_attach()] function. If zTbl does not exist, or if it
** does not have a primary key, this function is a no-op (but does not return
** an error).
**
** Argument zFromDb must be the name of a database ("main", "temp" etc.)
** attached to the same database handle as the session object that contains
** a table compatible with the table attached to the session by this function.
** A table is considered compatible if it:
**
** <ul>
** <li> Has the same name,
** <li> Has the same set of columns declared in the same order, and
** <li> Has the same PRIMARY KEY definition.
** </ul>
**
** If the tables are not compatible, SQLITE_SCHEMA is returned. If the tables
** are compatible but do not have any PRIMARY KEY columns, it is not an error
** but no changes are added to the session object. As with other session
** APIs, tables without PRIMARY KEYs are simply ignored.
**
** This function adds a set of changes to the session object that could be
** used to update the table in database zFrom (call this the "from-table")
** so that its content is the same as the table attached to the session
** object (call this the "to-table"). Specifically:
**
** <ul>
** <li> For each row (primary key) that exists in the to-table but not in
** the from-table, an INSERT record is added to the session object.
**
** <li> For each row (primary key) that exists in the to-table but not in
** the from-table, a DELETE record is added to the session object.
**
** <li> For each row (primary key) that exists in both tables, but features
** different in each, an UPDATE record is added to the session.
** </ul>
**
** To clarify, if this function is called and then a changeset constructed
** using [sqlite3session_changeset()], then after applying that changeset to
** database zFrom the contents of the two compatible tables would be
** identical.
**
** It an error if database zFrom does not exist or does not contain the
** required compatible table.
**
** If the operation successful, SQLITE_OK is returned. Otherwise, an SQLite
** error code. In this case, if argument pzErrMsg is not NULL, *pzErrMsg
** may be set to point to a buffer containing an English language error
** message. It is the responsibility of the caller to free this buffer using
** sqlite3_free().
*/
int sqlite3session_diff(
sqlite3_session *pSession,
const char *zFromDb,
const char *zTbl,
char **pzErrMsg
);
/*
** CAPI3REF: Generate A Patchset From A Session Object
**
** The differences between a patchset and a changeset are that:
**
** <ul>
** <li> DELETE records consist of the primary key fields only. The
** original values of other fields are omitted.
** <li> The original values of any modified fields are omitted from
** UPDATE records.
** </ul>
**
** A patchset blob may be used with up to date versions of all
** sqlite3changeset_xxx API functions except for sqlite3changeset_invert(),
** which returns SQLITE_CORRUPT if it is passed a patchset. Similarly,
** attempting to use a patchset blob with old versions of the
** sqlite3changeset_xxx APIs also provokes an SQLITE_CORRUPT error.
**
** Because the non-primary key "old.*" fields are omitted, no
** SQLITE_CHANGESET_DATA conflicts can be detected or reported if a patchset
** is passed to the sqlite3changeset_apply() API. Other conflict types work
** in the same way as for changesets.
**
** Changes within a patchset are ordered in the same way as for changesets
** generated by the sqlite3session_changeset() function (i.e. all changes for
** a single table are grouped together, tables appear in the order in which
** they were attached to the session object).
*/
int sqlite3session_patchset(
sqlite3_session *pSession, /* Session object */
int *pnPatchset, /* OUT: Size of buffer at *ppChangeset */
void **ppPatchset /* OUT: Buffer containing changeset */
);
/*
** CAPI3REF: Test if a changeset has recorded any changes.
**
** Return non-zero if no changes to attached tables have been recorded by
** the session object passed as the first argument. Otherwise, if one or
** more changes have been recorded, return zero.
**
** Even if this function returns zero, it is possible that calling
** [sqlite3session_changeset()] on the session handle may still return a
** changeset that contains no changes. This can happen when a row in
** an attached table is modified and then later on the original values
** are restored. However, if this function returns non-zero, then it is
** guaranteed that a call to sqlite3session_changeset() will return a
** changeset containing zero changes.
*/
int sqlite3session_isempty(sqlite3_session *pSession);
/*
** CAPI3REF: Create An Iterator To Traverse A Changeset
**
** Create an iterator used to iterate through the contents of a changeset.
** If successful, *pp is set to point to the iterator handle and SQLITE_OK
** is returned. Otherwise, if an error occurs, *pp is set to zero and an
** SQLite error code is returned.
**
** The following functions can be used to advance and query a changeset
** iterator created by this function:
**
** <ul>
** <li> [sqlite3changeset_next()]
** <li> [sqlite3changeset_op()]
** <li> [sqlite3changeset_new()]
** <li> [sqlite3changeset_old()]
** </ul>
**
** It is the responsibility of the caller to eventually destroy the iterator
** by passing it to [sqlite3changeset_finalize()]. The buffer containing the
** changeset (pChangeset) must remain valid until after the iterator is
** destroyed.
**
** Assuming the changeset blob was created by one of the
** [sqlite3session_changeset()], [sqlite3changeset_concat()] or
** [sqlite3changeset_invert()] functions, all changes within the changeset
** that apply to a single table are grouped together. This means that when
** an application iterates through a changeset using an iterator created by
** this function, all changes that relate to a single table are visted
** consecutively. There is no chance that the iterator will visit a change
** the applies to table X, then one for table Y, and then later on visit
** another change for table X.
*/
int sqlite3changeset_start(
sqlite3_changeset_iter **pp, /* OUT: New changeset iterator handle */
int nChangeset, /* Size of changeset blob in bytes */
void *pChangeset /* Pointer to blob containing changeset */
);
/*
** CAPI3REF: Advance A Changeset Iterator
**
** This function may only be used with iterators created by function
** [sqlite3changeset_start()]. If it is called on an iterator passed to
** a conflict-handler callback by [sqlite3changeset_apply()], SQLITE_MISUSE
** is returned and the call has no effect.
**
** Immediately after an iterator is created by sqlite3changeset_start(), it
** does not point to any change in the changeset. Assuming the changeset
** is not empty, the first call to this function advances the iterator to
** point to the first change in the changeset. Each subsequent call advances
** the iterator to point to the next change in the changeset (if any). If
** no error occurs and the iterator points to a valid change after a call
** to sqlite3changeset_next() has advanced it, SQLITE_ROW is returned.
** Otherwise, if all changes in the changeset have already been visited,
** SQLITE_DONE is returned.
**
** If an error occurs, an SQLite error code is returned. Possible error
** codes include SQLITE_CORRUPT (if the changeset buffer is corrupt) or
** SQLITE_NOMEM.
*/
int sqlite3changeset_next(sqlite3_changeset_iter *pIter);
/*
** CAPI3REF: Obtain The Current Operation From A Changeset Iterator
**
** The pIter argument passed to this function may either be an iterator
** passed to a conflict-handler by [sqlite3changeset_apply()], or an iterator
** created by [sqlite3changeset_start()]. In the latter case, the most recent
** call to [sqlite3changeset_next()] must have returned [SQLITE_ROW]. If this
** is not the case, this function returns [SQLITE_MISUSE].
**
** If argument pzTab is not NULL, then *pzTab is set to point to a
** nul-terminated utf-8 encoded string containing the name of the table
** affected by the current change. The buffer remains valid until either
** sqlite3changeset_next() is called on the iterator or until the
** conflict-handler function returns. If pnCol is not NULL, then *pnCol is
** set to the number of columns in the table affected by the change. If
** pbIncorrect is not NULL, then *pbIndirect is set to true (1) if the change
** is an indirect change, or false (0) otherwise. See the documentation for
** [sqlite3session_indirect()] for a description of direct and indirect
** changes. Finally, if pOp is not NULL, then *pOp is set to one of
** [SQLITE_INSERT], [SQLITE_DELETE] or [SQLITE_UPDATE], depending on the
** type of change that the iterator currently points to.
**
** If no error occurs, SQLITE_OK is returned. If an error does occur, an
** SQLite error code is returned. The values of the output variables may not
** be trusted in this case.
*/
int sqlite3changeset_op(
sqlite3_changeset_iter *pIter, /* Iterator object */
const char **pzTab, /* OUT: Pointer to table name */
int *pnCol, /* OUT: Number of columns in table */
int *pOp, /* OUT: SQLITE_INSERT, DELETE or UPDATE */
int *pbIndirect /* OUT: True for an 'indirect' change */
);
/*
** CAPI3REF: Obtain The Primary Key Definition Of A Table
**
** For each modified table, a changeset includes the following:
**
** <ul>
** <li> The number of columns in the table, and
** <li> Which of those columns make up the tables PRIMARY KEY.
** </ul>
**
** This function is used to find which columns comprise the PRIMARY KEY of
** the table modified by the change that iterator pIter currently points to.
** If successful, *pabPK is set to point to an array of nCol entries, where
** nCol is the number of columns in the table. Elements of *pabPK are set to
** 0x01 if the corresponding column is part of the tables primary key, or
** 0x00 if it is not.
**
** If argumet pnCol is not NULL, then *pnCol is set to the number of columns
** in the table.
**
** If this function is called when the iterator does not point to a valid
** entry, SQLITE_MISUSE is returned and the output variables zeroed. Otherwise,
** SQLITE_OK is returned and the output variables populated as described
** above.
*/
int sqlite3changeset_pk(
sqlite3_changeset_iter *pIter, /* Iterator object */
unsigned char **pabPK, /* OUT: Array of boolean - true for PK cols */
int *pnCol /* OUT: Number of entries in output array */
);
/*
** CAPI3REF: Obtain old.* Values From A Changeset Iterator
**
** The pIter argument passed to this function may either be an iterator
** passed to a conflict-handler by [sqlite3changeset_apply()], or an iterator
** created by [sqlite3changeset_start()]. In the latter case, the most recent
** call to [sqlite3changeset_next()] must have returned SQLITE_ROW.
** Furthermore, it may only be called if the type of change that the iterator
** currently points to is either [SQLITE_DELETE] or [SQLITE_UPDATE]. Otherwise,
** this function returns [SQLITE_MISUSE] and sets *ppValue to NULL.
**
** Argument iVal must be greater than or equal to 0, and less than the number
** of columns in the table affected by the current change. Otherwise,
** [SQLITE_RANGE] is returned and *ppValue is set to NULL.
**
** If successful, this function sets *ppValue to point to a protected
** sqlite3_value object containing the iVal'th value from the vector of
** original row values stored as part of the UPDATE or DELETE change and
** returns SQLITE_OK. The name of the function comes from the fact that this
** is similar to the "old.*" columns available to update or delete triggers.
**
** If some other error occurs (e.g. an OOM condition), an SQLite error code
** is returned and *ppValue is set to NULL.
*/
int sqlite3changeset_old(
sqlite3_changeset_iter *pIter, /* Changeset iterator */
int iVal, /* Column number */
sqlite3_value **ppValue /* OUT: Old value (or NULL pointer) */
);
/*
** CAPI3REF: Obtain new.* Values From A Changeset Iterator
**
** The pIter argument passed to this function may either be an iterator
** passed to a conflict-handler by [sqlite3changeset_apply()], or an iterator
** created by [sqlite3changeset_start()]. In the latter case, the most recent
** call to [sqlite3changeset_next()] must have returned SQLITE_ROW.
** Furthermore, it may only be called if the type of change that the iterator
** currently points to is either [SQLITE_UPDATE] or [SQLITE_INSERT]. Otherwise,
** this function returns [SQLITE_MISUSE] and sets *ppValue to NULL.
**
** Argument iVal must be greater than or equal to 0, and less than the number
** of columns in the table affected by the current change. Otherwise,
** [SQLITE_RANGE] is returned and *ppValue is set to NULL.
**
** If successful, this function sets *ppValue to point to a protected
** sqlite3_value object containing the iVal'th value from the vector of
** new row values stored as part of the UPDATE or INSERT change and
** returns SQLITE_OK. If the change is an UPDATE and does not include
** a new value for the requested column, *ppValue is set to NULL and
** SQLITE_OK returned. The name of the function comes from the fact that
** this is similar to the "new.*" columns available to update or delete
** triggers.
**
** If some other error occurs (e.g. an OOM condition), an SQLite error code
** is returned and *ppValue is set to NULL.
*/
int sqlite3changeset_new(
sqlite3_changeset_iter *pIter, /* Changeset iterator */
int iVal, /* Column number */
sqlite3_value **ppValue /* OUT: New value (or NULL pointer) */
);
/*
** CAPI3REF: Obtain Conflicting Row Values From A Changeset Iterator
**
** This function should only be used with iterator objects passed to a
** conflict-handler callback by [sqlite3changeset_apply()] with either
** [SQLITE_CHANGESET_DATA] or [SQLITE_CHANGESET_CONFLICT]. If this function
** is called on any other iterator, [SQLITE_MISUSE] is returned and *ppValue
** is set to NULL.
**
** Argument iVal must be greater than or equal to 0, and less than the number
** of columns in the table affected by the current change. Otherwise,
** [SQLITE_RANGE] is returned and *ppValue is set to NULL.
**
** If successful, this function sets *ppValue to point to a protected
** sqlite3_value object containing the iVal'th value from the
** "conflicting row" associated with the current conflict-handler callback
** and returns SQLITE_OK.
**
** If some other error occurs (e.g. an OOM condition), an SQLite error code
** is returned and *ppValue is set to NULL.
*/
int sqlite3changeset_conflict(
sqlite3_changeset_iter *pIter, /* Changeset iterator */
int iVal, /* Column number */
sqlite3_value **ppValue /* OUT: Value from conflicting row */
);
/*
** CAPI3REF: Determine The Number Of Foreign Key Constraint Violations
**
** This function may only be called with an iterator passed to an
** SQLITE_CHANGESET_FOREIGN_KEY conflict handler callback. In this case
** it sets the output variable to the total number of known foreign key
** violations in the destination database and returns SQLITE_OK.
**
** In all other cases this function returns SQLITE_MISUSE.
*/
int sqlite3changeset_fk_conflicts(
sqlite3_changeset_iter *pIter, /* Changeset iterator */
int *pnOut /* OUT: Number of FK violations */
);
/*
** CAPI3REF: Finalize A Changeset Iterator
**
** This function is used to finalize an iterator allocated with
** [sqlite3changeset_start()].
**
** This function should only be called on iterators created using the
** [sqlite3changeset_start()] function. If an application calls this
** function with an iterator passed to a conflict-handler by
** [sqlite3changeset_apply()], [SQLITE_MISUSE] is immediately returned and the
** call has no effect.
**
** If an error was encountered within a call to an sqlite3changeset_xxx()
** function (for example an [SQLITE_CORRUPT] in [sqlite3changeset_next()] or an
** [SQLITE_NOMEM] in [sqlite3changeset_new()]) then an error code corresponding
** to that error is returned by this function. Otherwise, SQLITE_OK is
** returned. This is to allow the following pattern (pseudo-code):
**
** sqlite3changeset_start();
** while( SQLITE_ROW==sqlite3changeset_next() ){
** // Do something with change.
** }
** rc = sqlite3changeset_finalize();
** if( rc!=SQLITE_OK ){
** // An error has occurred
** }
*/
int sqlite3changeset_finalize(sqlite3_changeset_iter *pIter);
/*
** CAPI3REF: Invert A Changeset
**
** This function is used to "invert" a changeset object. Applying an inverted
** changeset to a database reverses the effects of applying the uninverted
** changeset. Specifically:
**
** <ul>
** <li> Each DELETE change is changed to an INSERT, and
** <li> Each INSERT change is changed to a DELETE, and
** <li> For each UPDATE change, the old.* and new.* values are exchanged.
** </ul>
**
** This function does not change the order in which changes appear within
** the changeset. It merely reverses the sense of each individual change.
**
** If successful, a pointer to a buffer containing the inverted changeset
** is stored in *ppOut, the size of the same buffer is stored in *pnOut, and
** SQLITE_OK is returned. If an error occurs, both *pnOut and *ppOut are
** zeroed and an SQLite error code returned.
**
** It is the responsibility of the caller to eventually call sqlite3_free()
** on the *ppOut pointer to free the buffer allocation following a successful
** call to this function.
**
** WARNING/TODO: This function currently assumes that the input is a valid
** changeset. If it is not, the results are undefined.
*/
int sqlite3changeset_invert(
int nIn, const void *pIn, /* Input changeset */
int *pnOut, void **ppOut /* OUT: Inverse of input */
);
/*
** CAPI3REF: Concatenate Two Changeset Objects
**
** This function is used to concatenate two changesets, A and B, into a
** single changeset. The result is a changeset equivalent to applying
** changeset A followed by changeset B.
**
** This function combines the two input changesets using an
** sqlite3_changegroup object. Calling it produces similar results as the
** following code fragment:
**
** sqlite3_changegroup *pGrp;
** rc = sqlite3_changegroup_new(&pGrp);
** if( rc==SQLITE_OK ) rc = sqlite3changegroup_add(pGrp, nA, pA);
** if( rc==SQLITE_OK ) rc = sqlite3changegroup_add(pGrp, nB, pB);
** if( rc==SQLITE_OK ){
** rc = sqlite3changegroup_output(pGrp, pnOut, ppOut);
** }else{
** *ppOut = 0;
** *pnOut = 0;
** }
**
** Refer to the sqlite3_changegroup documentation below for details.
*/
int sqlite3changeset_concat(
int nA, /* Number of bytes in buffer pA */
void *pA, /* Pointer to buffer containing changeset A */
int nB, /* Number of bytes in buffer pB */
void *pB, /* Pointer to buffer containing changeset B */
int *pnOut, /* OUT: Number of bytes in output changeset */
void **ppOut /* OUT: Buffer containing output changeset */
);
/*
** Changegroup handle.
*/
typedef struct sqlite3_changegroup sqlite3_changegroup;
/*
** CAPI3REF: Combine two or more changesets into a single changeset.
**
** An sqlite3_changegroup object is used to combine two or more changesets
** (or patchsets) into a single changeset (or patchset). A single changegroup
** object may combine changesets or patchsets, but not both. The output is
** always in the same format as the input.
**
** If successful, this function returns SQLITE_OK and populates (*pp) with
** a pointer to a new sqlite3_changegroup object before returning. The caller
** should eventually free the returned object using a call to
** sqlite3changegroup_delete(). If an error occurs, an SQLite error code
** (i.e. SQLITE_NOMEM) is returned and *pp is set to NULL.
**
** The usual usage pattern for an sqlite3_changegroup object is as follows:
**
** <ul>
** <li> It is created using a call to sqlite3changegroup_new().
**
** <li> Zero or more changesets (or patchsets) are added to the object
** by calling sqlite3changegroup_add().
**
** <li> The result of combining all input changesets together is obtained
** by the application via a call to sqlite3changegroup_output().
**
** <li> The object is deleted using a call to sqlite3changegroup_delete().
** </ul>
**
** Any number of calls to add() and output() may be made between the calls to
** new() and delete(), and in any order.
**
** As well as the regular sqlite3changegroup_add() and
** sqlite3changegroup_output() functions, also available are the streaming
** versions sqlite3changegroup_add_strm() and sqlite3changegroup_output_strm().
*/
int sqlite3changegroup_new(sqlite3_changegroup **pp);
/*
** Add all changes within the changeset (or patchset) in buffer pData (size
** nData bytes) to the changegroup.
**
** If the buffer contains a patchset, then all prior calls to this function
** on the same changegroup object must also have specified patchsets. Or, if
** the buffer contains a changeset, so must have the earlier calls to this
** function. Otherwise, SQLITE_ERROR is returned and no changes are added
** to the changegroup.
**
** Rows within the changeset and changegroup are identified by the values in
** their PRIMARY KEY columns. A change in the changeset is considered to
** apply to the same row as a change already present in the changegroup if
** the two rows have the same primary key.
**
** Changes to rows that that do not already appear in the changegroup are
** simply copied into it. Or, if both the new changeset and the changegroup
** contain changes that apply to a single row, the final contents of the
** changegroup depends on the type of each change, as follows:
**
** <table border=1 style="margin-left:8ex;margin-right:8ex">
** <tr><th style="white-space:pre">Existing Change </th>
** <th style="white-space:pre">New Change </th>
** <th>Output Change
** <tr><td>INSERT <td>INSERT <td>
** The new change is ignored. This case does not occur if the new
** changeset was recorded immediately after the changesets already
** added to the changegroup.
** <tr><td>INSERT <td>UPDATE <td>
** The INSERT change remains in the changegroup. The values in the
** INSERT change are modified as if the row was inserted by the
** existing change and then updated according to the new change.
** <tr><td>INSERT <td>DELETE <td>
** The existing INSERT is removed from the changegroup. The DELETE is
** not added.
** <tr><td>UPDATE <td>INSERT <td>
** The new change is ignored. This case does not occur if the new
** changeset was recorded immediately after the changesets already
** added to the changegroup.
** <tr><td>UPDATE <td>UPDATE <td>
** The existing UPDATE remains within the changegroup. It is amended
** so that the accompanying values are as if the row was updated once
** by the existing change and then again by the new change.
** <tr><td>UPDATE <td>DELETE <td>
** The existing UPDATE is replaced by the new DELETE within the
** changegroup.
** <tr><td>DELETE <td>INSERT <td>
** If one or more of the column values in the row inserted by the
** new change differ from those in the row deleted by the existing
** change, the existing DELETE is replaced by an UPDATE within the
** changegroup. Otherwise, if the inserted row is exactly the same
** as the deleted row, the existing DELETE is simply discarded.
** <tr><td>DELETE <td>UPDATE <td>
** The new change is ignored. This case does not occur if the new
** changeset was recorded immediately after the changesets already
** added to the changegroup.
** <tr><td>DELETE <td>DELETE <td>
** The new change is ignored. This case does not occur if the new
** changeset was recorded immediately after the changesets already
** added to the changegroup.
** </table>
**
** If the new changeset contains changes to a table that is already present
** in the changegroup, then the number of columns and the position of the
** primary key columns for the table must be consistent. If this is not the
** case, this function fails with SQLITE_SCHEMA. If the input changeset
** appears to be corrupt and the corruption is detected, SQLITE_CORRUPT is
** returned. Or, if an out-of-memory condition occurs during processing, this
** function returns SQLITE_NOMEM. In all cases, if an error occurs the
** final contents of the changegroup is undefined.
**
** If no error occurs, SQLITE_OK is returned.
*/
int sqlite3changegroup_add(sqlite3_changegroup*, int nData, void *pData);
/*
** Obtain a buffer containing a changeset (or patchset) representing the
** current contents of the changegroup. If the inputs to the changegroup
** were themselves changesets, the output is a changeset. Or, if the
** inputs were patchsets, the output is also a patchset.
**
** As with the output of the sqlite3session_changeset() and
** sqlite3session_patchset() functions, all changes related to a single
** table are grouped together in the output of this function. Tables appear
** in the same order as for the very first changeset added to the changegroup.
** If the second or subsequent changesets added to the changegroup contain
** changes for tables that do not appear in the first changeset, they are
** appended onto the end of the output changeset, again in the order in
** which they are first encountered.
**
** If an error occurs, an SQLite error code is returned and the output
** variables (*pnData) and (*ppData) are set to 0. Otherwise, SQLITE_OK
** is returned and the output variables are set to the size of and a
** pointer to the output buffer, respectively. In this case it is the
** responsibility of the caller to eventually free the buffer using a
** call to sqlite3_free().
*/
int sqlite3changegroup_output(
sqlite3_changegroup*,
int *pnData, /* OUT: Size of output buffer in bytes */
void **ppData /* OUT: Pointer to output buffer */
);
/*
** Delete a changegroup object.
*/
void sqlite3changegroup_delete(sqlite3_changegroup*);
/*
** CAPI3REF: Apply A Changeset To A Database
**
** Apply a changeset to a database. This function attempts to update the
** "main" database attached to handle db with the changes found in the
** changeset passed via the second and third arguments.
**
** The fourth argument (xFilter) passed to this function is the "filter
** callback". If it is not NULL, then for each table affected by at least one
** change in the changeset, the filter callback is invoked with
** the table name as the second argument, and a copy of the context pointer
** passed as the sixth argument to this function as the first. If the "filter
** callback" returns zero, then no attempt is made to apply any changes to
** the table. Otherwise, if the return value is non-zero or the xFilter
** argument to this function is NULL, all changes related to the table are
** attempted.
**
** For each table that is not excluded by the filter callback, this function
** tests that the target database contains a compatible table. A table is
** considered compatible if all of the following are true:
**
** <ul>
** <li> The table has the same name as the name recorded in the
** changeset, and
** <li> The table has the same number of columns as recorded in the
** changeset, and
** <li> The table has primary key columns in the same position as
** recorded in the changeset.
** </ul>
**
** If there is no compatible table, it is not an error, but none of the
** changes associated with the table are applied. A warning message is issued
** via the sqlite3_log() mechanism with the error code SQLITE_SCHEMA. At most
** one such warning is issued for each table in the changeset.
**
** For each change for which there is a compatible table, an attempt is made
** to modify the table contents according to the UPDATE, INSERT or DELETE
** change. If a change cannot be applied cleanly, the conflict handler
** function passed as the fifth argument to sqlite3changeset_apply() may be
** invoked. A description of exactly when the conflict handler is invoked for
** each type of change is below.
**
** Unlike the xFilter argument, xConflict may not be passed NULL. The results
** of passing anything other than a valid function pointer as the xConflict
** argument are undefined.
**
** Each time the conflict handler function is invoked, it must return one
** of [SQLITE_CHANGESET_OMIT], [SQLITE_CHANGESET_ABORT] or
** [SQLITE_CHANGESET_REPLACE]. SQLITE_CHANGESET_REPLACE may only be returned
** if the second argument passed to the conflict handler is either
** SQLITE_CHANGESET_DATA or SQLITE_CHANGESET_CONFLICT. If the conflict-handler
** returns an illegal value, any changes already made are rolled back and
** the call to sqlite3changeset_apply() returns SQLITE_MISUSE. Different
** actions are taken by sqlite3changeset_apply() depending on the value
** returned by each invocation of the conflict-handler function. Refer to
** the documentation for the three
** [SQLITE_CHANGESET_OMIT|available return values] for details.
**
** <dl>
** <dt>DELETE Changes<dd>
** For each DELETE change, this function checks if the target database
** contains a row with the same primary key value (or values) as the
** original row values stored in the changeset. If it does, and the values
** stored in all non-primary key columns also match the values stored in
** the changeset the row is deleted from the target database.
**
** If a row with matching primary key values is found, but one or more of
** the non-primary key fields contains a value different from the original
** row value stored in the changeset, the conflict-handler function is
** invoked with [SQLITE_CHANGESET_DATA] as the second argument.
**
** If no row with matching primary key values is found in the database,
** the conflict-handler function is invoked with [SQLITE_CHANGESET_NOTFOUND]
** passed as the second argument.
**
** If the DELETE operation is attempted, but SQLite returns SQLITE_CONSTRAINT
** (which can only happen if a foreign key constraint is violated), the
** conflict-handler function is invoked with [SQLITE_CHANGESET_CONSTRAINT]
** passed as the second argument. This includes the case where the DELETE
** operation is attempted because an earlier call to the conflict handler
** function returned [SQLITE_CHANGESET_REPLACE].
**
** <dt>INSERT Changes<dd>
** For each INSERT change, an attempt is made to insert the new row into
** the database.
**
** If the attempt to insert the row fails because the database already
** contains a row with the same primary key values, the conflict handler
** function is invoked with the second argument set to
** [SQLITE_CHANGESET_CONFLICT].
**
** If the attempt to insert the row fails because of some other constraint
** violation (e.g. NOT NULL or UNIQUE), the conflict handler function is
** invoked with the second argument set to [SQLITE_CHANGESET_CONSTRAINT].
** This includes the case where the INSERT operation is re-attempted because
** an earlier call to the conflict handler function returned
** [SQLITE_CHANGESET_REPLACE].
**
** <dt>UPDATE Changes<dd>
** For each UPDATE change, this function checks if the target database
** contains a row with the same primary key value (or values) as the
** original row values stored in the changeset. If it does, and the values
** stored in all non-primary key columns also match the values stored in
** the changeset the row is updated within the target database.
**
** If a row with matching primary key values is found, but one or more of
** the non-primary key fields contains a value different from an original
** row value stored in the changeset, the conflict-handler function is
** invoked with [SQLITE_CHANGESET_DATA] as the second argument. Since
** UPDATE changes only contain values for non-primary key fields that are
** to be modified, only those fields need to match the original values to
** avoid the SQLITE_CHANGESET_DATA conflict-handler callback.
**
** If no row with matching primary key values is found in the database,
** the conflict-handler function is invoked with [SQLITE_CHANGESET_NOTFOUND]
** passed as the second argument.
**
** If the UPDATE operation is attempted, but SQLite returns
** SQLITE_CONSTRAINT, the conflict-handler function is invoked with
** [SQLITE_CHANGESET_CONSTRAINT] passed as the second argument.
** This includes the case where the UPDATE operation is attempted after
** an earlier call to the conflict handler function returned