Updated: 2022/Sep/29
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SQLITE3CHANGESET_APPLY_STRM(3) Library Functions Manual
NAME
sqlite3changeset_apply_strm, sqlite3changeset_apply_v2_strm,
sqlite3changeset_concat_strm, sqlite3changeset_invert_strm,
sqlite3changeset_start_strm, sqlite3changeset_start_v2_strm,
sqlite3session_changeset_strm, sqlite3session_patchset_strm,
sqlite3changegroup_add_strm, sqlite3changegroup_output_strm,
sqlite3rebaser_rebase_strm - streaming versions of API functions
SYNOPSIS
#include <sqlite3.h>
int
sqlite3changeset_apply_strm(sqlite3 *db,
int (*xInput)(void *pIn, void *pData, int *pnData), void *pIn,
int(*xFilter)( void *pCtx,const char *zTab),
int(*xConflict)( void *pCtx,int eConflict,sqlite3_changeset_iter *p),
void *pCtx);
int
sqlite3changeset_apply_v2_strm(sqlite3 *db,
int (*xInput)(void *pIn, void *pData, int *pnData), void *pIn,
int(*xFilter)( void *pCtx,const char *zTab),
int(*xConflict)( void *pCtx,int eConflict,sqlite3_changeset_iter *p),
void *pCtx, void **ppRebase, int *pnRebase, int flags);
int
sqlite3changeset_concat_strm(int (*xInputA)(void *pIn, void *pData, int *pnData),
void *pInA, int (*xInputB)(void *pIn, void *pData, int *pnData),
void *pInB, int (*xOutput)(void *pOut, const void *pData, int nData),
void *pOut);
int
sqlite3changeset_invert_strm(int (*xInput)(void *pIn, void *pData, int *pnData),
void *pIn, int (*xOutput)(void *pOut, const void *pData, int nData),
void *pOut);
int
sqlite3changeset_start_strm(sqlite3_changeset_iter **pp,
int (*xInput)(void *pIn, void *pData, int *pnData), void *pIn);
int
sqlite3changeset_start_v2_strm(sqlite3_changeset_iter **pp,
int (*xInput)(void *pIn, void *pData, int *pnData), void *pIn,
int flags);
int
sqlite3session_changeset_strm(sqlite3_session *pSession,
int (*xOutput)(void *pOut, const void *pData, int nData),
void *pOut);
int
sqlite3session_patchset_strm(sqlite3_session *pSession,
int (*xOutput)(void *pOut, const void *pData, int nData),
void *pOut);
int
sqlite3changegroup_add_strm(sqlite3_changegroup*,
int (*xInput)(void *pIn, void *pData, int *pnData), void *pIn);
int
sqlite3changegroup_output_strm(sqlite3_changegroup*,
int (*xOutput)(void *pOut, const void *pData, int nData),
void *pOut);
int
sqlite3rebaser_rebase_strm(sqlite3_rebaser *pRebaser,
int (*xInput)(void *pIn, void *pData, int *pnData), void *pIn,
int (*xOutput)(void *pOut, const void *pData, int nData),
void *pOut);
DESCRIPTION
The six streaming API xxx_strm() functions serve similar purposes to the
corresponding non-streaming API functions:
Streaming function Non-streaming equivalent
sqlite3changeset_apply_strm sqlite3changeset_apply
sqlite3changeset_apply_strm_v2 sqlite3changeset_apply_v2
sqlite3changeset_concat_strm sqlite3changeset_concat
sqlite3changeset_invert_strm sqlite3changeset_invert
sqlite3changeset_start_strm sqlite3changeset_start
sqlite3session_changeset_strm sqlite3session_changeset
sqlite3session_patchset_strm sqlite3session_patchset
Non-streaming functions that accept changesets (or patchsets) as input
require that the entire changeset be stored in a single buffer in memory.
Similarly, those that return a changeset or patchset do so by returning a
pointer to a single large buffer allocated using sqlite3_malloc().
Normally this is convenient. However, if an application running in a
low-memory environment is required to handle very large changesets, the
large contiguous memory allocations required can become onerous.
In order to avoid this problem, instead of a single large buffer, input
is passed to a streaming API functions by way of a callback function that
the sessions module invokes to incrementally request input data as it is
required. In all cases, a pair of API function parameters such as
int nChangeset, void *pChangeset,
Is replaced by:
int (*xInput)(void *pIn, void *pData, int *pnData), void
*pIn,
Each time the xInput callback is invoked by the sessions module, the
first argument passed is a copy of the supplied pIn context pointer. The
second argument, pData, points to a buffer (*pnData) bytes in size.
Assuming no error occurs the xInput method should copy up to (*pnData)
bytes of data into the buffer and set (*pnData) to the actual number of
bytes copied before returning SQLITE_OK. If the input is completely
exhausted, (*pnData) should be set to zero to indicate this. Or, if an
error occurs, an SQLite error code should be returned. In all cases, if
an xInput callback returns an error, all processing is abandoned and the
streaming API function returns a copy of the error code to the caller.
In the case of sqlite3changeset_start_strm(), the xInput callback may be
invoked by the sessions module at any point during the lifetime of the
iterator. If such an xInput callback returns an error, the iterator
enters an error state, whereby all subsequent calls to iterator functions
immediately fail with the same error code as returned by xInput.
Similarly, streaming API functions that return changesets (or patchsets)
return them in chunks by way of a callback function instead of via a
pointer to a single large buffer. In this case, a pair of parameters
such as:
int *pnChangeset, void **ppChangeset,
Is replaced by:
int (*xOutput)(void *pOut, const void *pData, int nData),
void *pOut
The xOutput callback is invoked zero or more times to return data to the
application. The first parameter passed to each call is a copy of the
pOut pointer supplied by the application. The second parameter, pData,
points to a buffer nData bytes in size containing the chunk of output
data being returned. If the xOutput callback successfully processes the
supplied data, it should return SQLITE_OK to indicate success.
Otherwise, it should return some other SQLite error code. In this case
processing is immediately abandoned and the streaming API function
returns a copy of the xOutput error code to the application.
The sessions module never invokes an xOutput callback with the third
parameter set to a value less than or equal to zero. Other than this, no
guarantees are made as to the size of the chunks of data returned.
IMPLEMENTATION NOTES
These declarations were extracted from the interface documentation at
line 12322.
SQLITE_API int sqlite3changeset_apply_strm(
sqlite3 *db, /* Apply change to "main" db of this handle */
int (*xInput)(void *pIn, void *pData, int *pnData), /* Input function */
void *pIn, /* First arg for xInput */
int(*xFilter)(
void *pCtx, /* Copy of sixth arg to _apply() */
const char *zTab /* Table name */
),
int(*xConflict)(
void *pCtx, /* Copy of sixth arg to _apply() */
int eConflict, /* DATA, MISSING, CONFLICT, CONSTRAINT */
sqlite3_changeset_iter *p /* Handle describing change and conflict */
),
void *pCtx /* First argument passed to xConflict */
);
SQLITE_API int sqlite3changeset_apply_v2_strm(
sqlite3 *db, /* Apply change to "main" db of this handle */
int (*xInput)(void *pIn, void *pData, int *pnData), /* Input function */
void *pIn, /* First arg for xInput */
int(*xFilter)(
void *pCtx, /* Copy of sixth arg to _apply() */
const char *zTab /* Table name */
),
int(*xConflict)(
void *pCtx, /* Copy of sixth arg to _apply() */
int eConflict, /* DATA, MISSING, CONFLICT, CONSTRAINT */
sqlite3_changeset_iter *p /* Handle describing change and conflict */
),
void *pCtx, /* First argument passed to xConflict */
void **ppRebase, int *pnRebase,
int flags
);
SQLITE_API int sqlite3changeset_concat_strm(
int (*xInputA)(void *pIn, void *pData, int *pnData),
void *pInA,
int (*xInputB)(void *pIn, void *pData, int *pnData),
void *pInB,
int (*xOutput)(void *pOut, const void *pData, int nData),
void *pOut
);
SQLITE_API int sqlite3changeset_invert_strm(
int (*xInput)(void *pIn, void *pData, int *pnData),
void *pIn,
int (*xOutput)(void *pOut, const void *pData, int nData),
void *pOut
);
SQLITE_API int sqlite3changeset_start_strm(
sqlite3_changeset_iter **pp,
int (*xInput)(void *pIn, void *pData, int *pnData),
void *pIn
);
SQLITE_API int sqlite3changeset_start_v2_strm(
sqlite3_changeset_iter **pp,
int (*xInput)(void *pIn, void *pData, int *pnData),
void *pIn,
int flags
);
SQLITE_API int sqlite3session_changeset_strm(
sqlite3_session *pSession,
int (*xOutput)(void *pOut, const void *pData, int nData),
void *pOut
);
SQLITE_API int sqlite3session_patchset_strm(
sqlite3_session *pSession,
int (*xOutput)(void *pOut, const void *pData, int nData),
void *pOut
);
SQLITE_API int sqlite3changegroup_add_strm(sqlite3_changegroup*,
int (*xInput)(void *pIn, void *pData, int *pnData),
void *pIn
);
SQLITE_API int sqlite3changegroup_output_strm(sqlite3_changegroup*,
int (*xOutput)(void *pOut, const void *pData, int nData),
void *pOut
);
SQLITE_API int sqlite3rebaser_rebase_strm(
sqlite3_rebaser *pRebaser,
int (*xInput)(void *pIn, void *pData, int *pnData),
void *pIn,
int (*xOutput)(void *pOut, const void *pData, int nData),
void *pOut
);
SEE ALSO
sqlite3changeset_apply(3), sqlite3changeset_concat(3),
sqlite3changeset_invert(3), sqlite3changeset_start(3),
sqlite3session_changeset(3), sqlite3session_patchset(3)
NetBSD 10.99 August 24, 2023 NetBSD 10.99