gaborkaszab commented on code in PR #16025:
URL: https://github.com/apache/iceberg/pull/16025#discussion_r3376322192
##########
format/spec.md:
##########
@@ -685,21 +701,100 @@ The `manifest_entry` struct consists of the following
fields:
| | _optional_ | **`4 file_sequence_number`** | `long`
| File sequence number indicating
when the file was added. Inherited when null and status is 1 (added). |
| _required_ | _required_ | **`2 data_file`** | `data_file`
`struct` (see below) | File path, partition tuple,
metrics, ... |
-The manifest entry fields are used to keep track of the snapshot in which
files were added or logically deleted. The `data_file` struct, defined below,
is nested inside the manifest entry so that it can be easily passed to job
planning without the manifest entry fields.
+ The manifest entry fields are used to keep track of the snapshot in which
files were added or logically deleted. The `data_file` struct, defined below,
is nested inside the manifest entry so that it can be easily passed to job
planning without the manifest entry fields.
-When a file is added to the dataset, its manifest entry should store the
snapshot ID in which the file was added and set status to 1 (added).
+ When a file is added to the dataset, its manifest entry should store the
snapshot ID in which the file was added and set status to 1 (added).
-When a file is replaced or deleted from the dataset, its manifest entry fields
store the snapshot ID in which the file was deleted and status 2 (deleted). The
file may be deleted from the file system when the snapshot in which it was
deleted is garbage collected, assuming that older snapshots have also been
garbage collected [1].
+ When a file is replaced or deleted from the dataset, its manifest entry
fields store the snapshot ID in which the file was deleted and status 2
(deleted). The file may be deleted from the file system when the snapshot in
which it was deleted is garbage collected, assuming that older snapshots have
also been garbage collected [1].
-Iceberg v2 adds data and file sequence numbers to the entry and makes the
snapshot ID optional. Values for these fields are inherited from manifest
metadata when `null`. That is, if the field is `null` for an entry, then the
entry must inherit its value from the manifest file's metadata, stored in the
manifest list.
-The `sequence_number` field represents the data sequence number and must never
change after a file is added to the dataset. The data sequence number
represents a relative age of the file content and should be used for planning
which delete files apply to a data file.
-The `file_sequence_number` field represents the sequence number of the
snapshot that added the file and must also remain unchanged upon assigning at
commit. The file sequence number can't be used for pruning delete files as the
data within the file may have an older data sequence number.
-The data and file sequence numbers are inherited only if the entry status is 1
(added). If the entry status is 0 (existing) or 2 (deleted), the entry must
include both sequence numbers explicitly.
+ Iceberg v2 adds data and file sequence numbers to the entry and makes the
snapshot ID optional. Values for these fields are inherited from manifest
metadata when `null`. That is, if the field is `null` for an entry, then the
entry must inherit its value from the manifest file's metadata, stored in the
manifest list.
+ The `sequence_number` field represents the data sequence number and must
never change after a file is added to the dataset. The data sequence number
represents a relative age of the file content and should be used for planning
which delete files apply to a data file.
+ The `file_sequence_number` field represents the sequence number of the
snapshot that added the file and must also remain unchanged upon assigning at
commit. The file sequence number can't be used for pruning delete files as the
data within the file may have an older data sequence number.
+ The data and file sequence numbers are inherited only if the entry status
is 1 (added). If the entry status is 0 (existing) or 2 (deleted), the entry
must include both sequence numbers explicitly.
-Notes:
+ Notes:
+
+ 1. Technically, data files can be deleted when the last snapshot that
contains the file as "live" data is garbage collected. But this is harder to
detect and requires finding the diff of multiple snapshots. It is easier to
track what files are deleted in a snapshot and delete them when that snapshot
expires. It is not recommended to add a deleted file back to a table. Adding a
deleted file can lead to edge cases where incremental deletes can break table
snapshots.
+ 2. Manifest list files are required in v2, so that the `sequence_number`
and `snapshot_id` to inherit are always available.
-1. Technically, data files can be deleted when the last snapshot that contains
the file as “live” data is garbage collected. But this is harder to detect and
requires finding the diff of multiple snapshots. It is easier to track what
files are deleted in a snapshot and delete them when that snapshot expires. It
is not recommended to add a deleted file back to a table. Adding a deleted file
can lead to edge cases where incremental deletes can break table snapshots.
-2. Manifest list files are required in v2, so that the `sequence_number` and
`snapshot_id` to inherit are always available.
+=== "v4"
+ **Content Entries**
+
+ | Field id | Name | Type | Write | Read | Description |
+ |----------|------|------|-------|------|-------------|
+ | 134 | **`content_type`** | `int` (0: DATA, 2: EQUALITY DELETES, 3:
DATA_MANIFEST, 4: DELETE_MANIFEST) | *required* | *required* | Type of content
stored in the entry. Content types 3 and 4 are only valid in root manifests. |
+ | 157 | **`writer_format_version`** | `int` (0: PRE-V4, 1: V4) |
*required* | *required* | Writer format version. V4 writers must produce
`writer_format_version` 1. |
+ | 100 | **`location`** | `string` | *required* | *required* | Location of
the file or manifest. |
+ | 101 | **`file_format`** | `string` | *required* | *required* | String
file format name: `avro`, `orc`, `parquet`, or `puffin` |
+ | 147 | **`tracking`** | `tracking` struct | *required* | *required* |
Groups status, snapshot, and sequence number. See tracking struct below. |
+ | 141 | **`spec_id`** | `int` | *optional* | *optional* | ID of the
partition spec used to write this manifest or data file. |
+ | 140 | **`sort_order_id`** | `int` | *optional* | *optional* | ID
representing sort order for this file. |
+ | 103 | **`record_count`** | `long` | *required* | *required* | Number of
records in this file. |
+ | 104 | **`file_size_in_bytes`** | `long` | *required* | *required* |
Total file size in bytes. |
+ | 146 | **`content_stats`** | `content_stats` struct | *optional* |
*optional* | Column stats. See [Column Stats
Improvements](#column-stats-improvements). |
+ | 150 | **`manifest_info`** | `manifest_info` struct | *optional* |
*optional* | See manifest_info struct below. |
+ | 131 | **`key_metadata`** | `binary` | *optional* | *optional* |
Implementation-specific key metadata for encryption. |
+ | 132 | **`split_offsets`** | `list<133: long>` | *optional* | *optional*
| Split offsets for the data file. Must be sorted ascending. |
+ | 135 | **`equality_ids`** | `list<136: int>` | *optional* | *optional* |
Field ids for row equality in equality delete files. |
+ | 148 | **`deletion_vector`** | `deletion_vector` struct | *optional* |
*optional* | Row-level deletion vector for a data file. |
+ | 158 | **`column_files`** | `list<column_file>` | *optional* | *optional*
| Column update files associated with this entry. |
+
+ Value 1 (POSITION_DELETES) is not used in v4. Writers must not produce
`content_type` 1.
+
+ V4 leaf data manifests must only contain entries with `content_type` 0
(DATA); V4 leaf delete manifests must only contain entries with `content_type`
2 (EQUALITY DELETES). A root manifest may reference V1-V3 manifests; V1-V3 leaf
manifest references must have `writer_format_version` set to 0.
+
+ The following constraints apply based on `content_type`:
+
+ - `manifest_info` must be set when `content_type` is 3 or 4; must be null
otherwise.
Review Comment:
Also ,should be null if `content_type` is 0 or 2, right?
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