RussellSpitzer commented on code in PR #11130:
URL: https://github.com/apache/iceberg/pull/11130#discussion_r1759578432
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format/spec.md:
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@@ -298,16 +298,137 @@ Iceberg tables must not use field ids greater than
2147483447 (`Integer.MAX_VALU
The set of metadata columns is:
-| Field id, name | Type | Description |
-|-----------------------------|---------------|-------------|
-| **`2147483646 _file`** | `string` | Path of the file in which a
row is stored |
-| **`2147483645 _pos`** | `long` | Ordinal position of a row in
the source data file |
-| **`2147483644 _deleted`** | `boolean` | Whether the row has been
deleted |
-| **`2147483643 _spec_id`** | `int` | Spec ID used to track the file
containing a row |
-| **`2147483642 _partition`** | `struct` | Partition to which a row
belongs |
-| **`2147483546 file_path`** | `string` | Path of a file, used in
position-based delete files |
-| **`2147483545 pos`** | `long` | Ordinal position of a row,
used in position-based delete files |
-| **`2147483544 row`** | `struct<...>` | Deleted row values, used in
position-based delete files |
+| Field id, name | Type | Description
|
+|-----------------------------------|---------------|-------------------------------------------------------------------------------|
+| **`2147483646 _file`** | `string` | Path of the file in
which a row is stored |
+| **`2147483645 _pos`** | `long` | Ordinal position of a
row in the source data file, starting at `0` |
+| **`2147483644 _deleted`** | `boolean` | Whether the row has been
deleted |
+| **`2147483643 _spec_id`** | `int` | Spec ID used to track
the file containing a row |
+| **`2147483642 _partition`** | `struct` | Partition to which a row
belongs |
+| **`2147483546 file_path`** | `string` | Path of a file, used in
position-based delete files |
+| **`2147483545 pos`** | `long` | Ordinal position of a
row, used in position-based delete files |
+| **`2147483544 row`** | `struct<...>` | Deleted row values, used
in position-based delete files |
+| **`2147483545 _row_identifier`** | `long` | A unique long assigned
when row-lineage is enabled see [Row Lineage](#row-lineage) |
+| **`2147483545 _last_update`** | `long` | The sequence number
which last updated this row when row-lineage is enabled [Row
Lineage](#row-lineage) |
+
+### Row Lineage
+
+In Specification V3, an Iceberg Table can declare that engines must track
row-lineage of all newly created rows. This
+requirement is controlled by setting the field `row-lineage` to true in the
table's metadata. When true, two additional
+fields in data files will be available for all rows added to the table.
+
+* `_row_identifier` a unique long for every row. Computed via inheritance for
rows in their original datafiles
Review Comment:
One possible alternative from the doc was to have this be a combination of a
random prefix and integer to remove the requirement of monotonic integer from
the metadata. Since we have other monotonic integers in the metadata, I think
this may not be that helpful unless we do a broad change.
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