Invert A Changeset

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Session Module C Interface

Invert A Changeset

int sqlite3changeset_invert(
  int nIn, const void *pIn,       /* Input changeset */
  int *pnOut, void **ppOut        /* OUT: Inverse of input */
);

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:

Each DELETE change is changed to an INSERT, and
Each INSERT change is changed to a DELETE, and
For each UPDATE change, the old.* and new.* values are exchanged.

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.

See also lists of Objects, Constants, and Functions.

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