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Spec: require monotonically increasing snapshot timestamp-ms in v4 #16294

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Merged
stevenzwu merged 4 commits into from
Oct 12, 2026
Merged

Spec: require monotonically increasing snapshot timestamp-ms in v4 #16294

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96b7b0d
Spec: require monotonically increasing snapshot timestamp-ms in v4
stevenzwu May 12, 2026
a41c747
Merge apache/main into spec-snapshot-timestamp-monotonic
stevenzwu Oct 1, 2026
dcfa302
Spec: clarify which v4 snapshots must have monotonic timestamps
stevenzwu Oct 1, 2026
611b7c2
Spec: clarify when v4 snapshot timestamps must be monotonic
stevenzwu Oct 8, 2026
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7 changes: 7 additions & 0 deletions format/spec.md
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Expand Up @@ -966,6 +966,8 @@ A snapshot consists of the following fields:
| | | _required_ | **`added-rows`** | The upper bound of the number of rows with assigned row IDs, see [Row Lineage](#row-lineage) |
| | | _optional_ | **`key-id`** | ID of the encryption key that encrypts the manifest list key metadata |

When committed while the table is at version 4 or higher, a snapshot's `timestamp-ms` must be strictly greater than its parent snapshot's `timestamp-ms` on the same branch. Snapshots with no parent, and snapshots that were committed before a table was upgraded to v4 or higher, do not have this requirement.

The snapshot summary's `operation` field is used by some operations, like snapshot expiration, to skip processing certain snapshots. Possible `operation` values are:

* `append` -- Only data files were added and no files were removed.
Expand Down Expand Up @@ -1918,6 +1920,11 @@ Reading v4 metadata:
* Relative paths must be resolved against the table location before use (see [Path Resolution](#path-resolution))
* When `location` is omitted, the table location must be provided (see [Table Location Specification](#table-location-specification))

Snapshot timestamp changes:

* When committed while the table is at version 4 or higher, a snapshot's `timestamp-ms` must be strictly greater than its parent snapshot's `timestamp-ms` on the same branch.
* Snapshots with no parent and snapshots that existed before a table was upgraded to v4 are not constrained.

Equality deletes are prohibited in v4.

* Writers must not add equality delete files to v4 tables; equality deletes cannot be added as an entry to a v4 manifest
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