Change Tracking Table

Table 10. _Cdc-Change-Tracking fields
Field	Size	Description
_Policy-Id	char(22)	Table Policy Id
_Tran-Id	integer	Transaction number
_Time-Stamp	timestamp tz	Timestamp of database trigger execution – UTC with zone
_Change-Sequence	int64	Sequence of change within the Object for a policy Id
_Operation	integer	Value to indicate what type of operation is occurring: 1 — Create 2 — Delete 3 — Before Update 4 — After Update 5 — Field Delete (in Source Table) 6 — Partition Drop 7 — Partition Truncate 8 — Partition Deallocate 9 — MT Partition Deallocate 10 — MT Partition Drop 11 — Merge Partition Drop 12 — Field Add (in Change Table, also specifies re-tracking of a field)
_Source-FieldMap	raw(256)	ABL/SQL methods are provided to access values in this field.
_Source-Rowid	int64	Support for Pro2
_Source-Partition-Id	integer	Support for TP
_Tenant-Id	integer	Support for MT
_Version	integer	Future to support change table record format changes
_User-Misc	char x(8)	User defined field — possible use to mark it when an operation has occurred that moved a record to the external data source.
_Misc	char x(8)	Reserved for future use

Table 11. _Cdc-Change-Tracking indexes
Index Name	Index Field	Attribute
_Sequence-Id	1 _Source-Table-Number (These two fields together point to a single instance of the table) 2 _Change-Sequence	Unique Primary
_Time-Stamp-Seq	1 _Source-Table-Number 2 _Time-Stamp 3 _Change-Sequence	Non Unique
_Part-Rec-Id	1 _Source-Table-Number 2 _Partition-Id 3 _Recid 4 _Change-Sequence	Unique

The CDC Change Tracking Table is a table used by all change record capture activities. The table tracks each CUD (create/update/delete) activity by a change sequence order. This table can be used to drive query activity in the CDC Change Table. The database CDC trigger will write a Change Tracking and Change Table record in most cases when it is executed. Understanding the connection between the two tables is important because data describing the change activity is stored in the Change Tracking Table. When accessing the the data in the Change Table, use the Change Tracking Table to establish record modification sequence and which fields changed in the Source Table.