** columns and columns that are modified by the UPDATE are set to "undefined".
** PRIMARY KEY fields contain the values identifying the table row to update,
** and fields associated with modified columns contain the new column values.
**
** The records associated with INSERT changes are in the same format as for
** changesets. It is not possible for a record associated with an INSERT
** change to contain a field set to "undefined".




































*/

/*
** For each row modified during a session, there exists a single instance of
** this structure stored in a SessionTable.aChange[] hash table.
*/
struct SessionChange {

** columns and columns that are modified by the UPDATE are set to "undefined".
** PRIMARY KEY fields contain the values identifying the table row to update,
** and fields associated with modified columns contain the new column values.
**
** The records associated with INSERT changes are in the same format as for
** changesets. It is not possible for a record associated with an INSERT
** change to contain a field set to "undefined".
**
** REBASE BLOB FORMAT:
**
** A rebase blob may be output by sqlite3changeset_apply_v2() and its 
** streaming equivalent for use with the sqlite3_rebaser APIs to rebase
** existing changesets. A rebase blob contains one entry for each conflict
** resolved using either the OMIT or REPLACE strategies within the apply_v2()
** call.
**
** The format used for a rebase blob is very similar to that used for
** changesets. All entries related to a single table are grouped together.
**
** Each group of entries begins with a table header in changeset format:
**
**   1 byte: Constant 0x54 (capital 'T')
**   Varint: Number of columns in the table.
**   nCol bytes: 0x01 for PK columns, 0x00 otherwise.
**   N bytes: Unqualified table name (encoded using UTF-8). Nul-terminated.
**
** Followed by one or more entries associated with the table.
**
**   1 byte: Either SQLITE_INSERT (0x12), DELETE (0x09).
**   1 byte: Flag. 0x01 for REPLACE, 0x00 for OMIT.
**   record: (in the record format defined above).
**
** In a rebase blob, the first field is set to SQLITE_INSERT if the change
** that caused the conflict was an INSERT or UPDATE, or to SQLITE_DELETE if
** it was a DELETE. The second field is set to 0x01 if the conflict 
** resolution strategy was REPLACE, or 0x00 if it was OMIT.
**
** If the change that caused the conflict was a DELETE, then the single
** record is a copy of the old.* record from the original changeset. If it
** was an INSERT, then the single record is a copy of the new.* record. If
** the conflicting change was an UPDATE, then the single record is a copy
** of the new.* record with the PK fields filled in based on the original
** old.* record.
*/

/*
** For each row modified during a session, there exists a single instance of
** this structure stored in a SessionTable.aChange[] hash table.
*/
struct SessionChange {