amogh-jahagirdar commented on code in PR #16025:
URL: https://github.com/apache/iceberg/pull/16025#discussion_r3928984811
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format/spec.md:
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@@ -691,21 +709,123 @@ 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 | Required | Description |
+ |----------|------|------|----------|-------------|
+ | 134 | **`content_type`** | `int` (0: DATA, 3: DATA_MANIFEST, 4:
DELETE_MANIFEST) | *required* | Type of content stored in the entry. Content
types 3 and 4 are only valid in root manifests. |
+ | 157 | **`format_version`** | `int` (0: PRE-V4, 4: V4) | *required* |
Writer format version. v4 writers must produce `format_version` 4. |
+ | 100 | **`location`** | `string` | *required* | Location of the file or
manifest. |
+ | 101 | **`file_format`** | `string` | *required* | String file format
name: `avro`, `orc`, `parquet`, or `puffin` |
+ | 147 | **`tracking`** | `tracking` struct | *required* | Groups status,
snapshot, and sequence number. See tracking struct below. |
+ | 141 | **`spec_id`** | `int` | *optional* | ID of the partition spec used
to write this manifest or data file. |
+ | 140 | **`sort_order_id`** | `int` | *optional* | ID representing sort
order for this file. |
+ | 103 | **`record_count`** | `long` | *required* | Number of records in
this file. |
+ | 104 | **`file_size_in_bytes`** | `long` | *required* | Total file size
in bytes. |
+ | 146 | **`content_stats`** | `content_stats` struct | *optional* | Column
stats. See [Column Stats Improvements](#column-stats-improvements). |
+ | 150 | **`manifest_info`** | `manifest_info` struct | *optional* | See
manifest_info struct below. |
+ | 131 | **`key_metadata`** | `binary` | *optional* |
Implementation-specific key metadata for encryption. |
+ | 132 | **`split_offsets`** | `list<133: long>` | *optional* | Split
offsets for the data file. Must be sorted ascending. |
+ | 148 | **`deletion_vector`** | `deletion_vector` struct | *optional* |
Row-level deletion vector for a data file. |
+ | 158 | **`column_files`** | `list<159: column_file>` | *optional* |
Column update files associated with this entry. |
+
+ Value 1 (POSITION_DELETES) is not used in v4. Writers must not produce
`content_type` 1.
+
+ Writers must not produce `content_type` 2 (EQUALITY DELETES) in v4.
+
+ v4 leaf manifests must only contain entries with `content_type` 0 (DATA).
A root manifest may reference v1-v3 manifests; v1-v3 leaf manifest references
must have `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.
+ - `deletion_vector` may only be set when `content_type` is 0; must be null
otherwise.
+ - `column_files` must be null when `content_type` is not 0 or 3.
+ - `sort_order_id` must be null when `content_type` is 3 or 4 (manifests).
+ - `split_offsets` must be null when `content_type` is 3 or 4 (manifests).
+ - `tracking.deleted_positions` and `tracking.replaced_positions` must be
null when `content_type` is not 3 or 4.
+
+ **`tracking` struct (field 147)**
+
+ | Field id | Name | Type | Required | Description |
+ |----------|------|------|----------|-------------|
+ | 0 | **`status`** | `int` (0: EXISTING, 1: ADDED, 2: DELETED, 3:
REPLACED, 4: MODIFIED) | *required* | Used to track additions, deletions,
replacements, and modifications. When a data file's `deletion_vector` or
`column_files` change, REPLACED marks the prior version of the entry and
MODIFIED marks the new, live version. For leaf manifest entries, MODIFIED marks
a live manifest whose `dv` changed. Deletes are not used in scans. |
+ | 1 | **`snapshot_id`** | `long` | *optional* | Snapshot ID where the file
was added or deleted. Inherited when null. Optional for leaf manifests,
required for root. |
+ | 5 | **`dv_snapshot_id`** | `long` | *optional* | Snapshot ID where the
deletion vector was added. Must be null when `deletion_vector` is null and `dv`
is null. |
+ | 160 | **`latest_column_file_snapshot_id`** | `long` | *optional* |
Snapshot ID where the latest column file was added. Inherited when null. Must
be null when `column_files` is null. |
+ | 3 | **`sequence_number`** | `long` | *optional* | Data sequence number
of the file. Inherited when null and status is 1 (ADDED). Must equal
`file_sequence_number` if `content_type` is 3 or 4. Optional for leaf
manifests, required for root. |
+ | 4 | **`file_sequence_number`** | `long` | *optional* | File sequence
number indicating when the file was added. Inherited when null and status is
ADDED. Must equal `sequence_number` if `content_type` is 3 or 4. |
+ | 142 | **`first_row_id`** | `long` | *optional* | The `_row_id` for the
first row in the data file if `content_type` is 0. If `content_type` is 3, this
is the starting `_row_id` to assign to rows added by ADDED data files. See
[First Row ID Inheritance](#first-row-id-inheritance). |
+ | 6 | **`deleted_positions`** | `binary` | *optional* | Mumbling bitmap of
positions in the referenced leaf manifest that were deleted in this snapshot. |
+ | 7 | **`replaced_positions`** | `binary` | *optional* | Mumbling bitmap
of positions in the referenced leaf manifest that were replaced in this
snapshot. |
+
+ **`deletion_vector` struct (field 148)**
+
+ | Field id | Name | Type | Required | Description |
+ |----------|------|------|----------|-------------|
+ | 155 | **`location`** | `string` | *required* | Location of the Puffin
file. |
+ | 144 | **`offset`** | `long` | *required* | Offset in the file where the
content starts. |
+ | 145 | **`size_in_bytes`** | `long` | *required* | Length of the
referenced content stored in the file. |
+ | 156 | **`cardinality`** | `long` | *required* | Cardinality of the
deletion vector. |
+ | 149 | **`key_metadata`** | `binary` | *optional* |
Implementation-specific key metadata for encryption. |
+
+ **`manifest_info` struct (field 150)**
+
+ | Field id | Name | Type | Required | Description |
+ |----------|------|------|----------|-------------|
+ | 504 | **`added_files_count`** | `long` | *required* | Count of entries
with status ADDED in the manifest. |
+ | 505 | **`existing_files_count`** | `long` | *required* | Count of
entries with status EXISTING in the manifest. |
+ | 506 | **`deleted_files_count`** | `long` | *required* | Count of entries
with status DELETED in the manifest. |
+ | 520 | **`replaced_files_count`** | `long` | *required* | Count of
entries with status REPLACED in the manifest. |
+ | 524 | **`modified_files_count`** | `long` | *required* | Count of
entries with status MODIFIED in the manifest. |
+ | 512 | **`added_rows_count`** | `long` | *required* | Total number of
rows in ADDED entries. |
+ | 513 | **`existing_rows_count`** | `long` | *required* | Total number of
rows in EXISTING entries. |
+ | 514 | **`deleted_rows_count`** | `long` | *required* | Total number of
rows in DELETED entries. |
+ | 521 | **`replaced_rows_count`** | `long` | *required* | Total number of
rows in REPLACED entries. |
+ | 525 | **`modified_rows_count`** | `long` | *required* | Total number of
rows in MODIFIED entries. |
+ | 516 | **`min_sequence_number`** | `long` | *required* | Minimum data
sequence number of all live entries in the manifest. |
+ | 522 | **`dv`** | `binary` | *optional* | Mumbling bitmap of entry
positions in the manifest that are not live in the current snapshot. |
+ | 523 | **`dv_cardinality`** | `long` | *optional* | Cardinality of the
manifest deletion vector. Must be set when `dv` is non-null; must be null
otherwise. |
+
+ **`column_file` struct (element 159 of `column_files`, field 158)**
+
+ | Field id | Name | Type | Required | Description |
+ |----------|------|------|----------|-------------|
+ | 161 | **`format_version`** | `int` | *required* | Format version of this
column file. |
+ | 162 | **`field_ids`** | `list<163: int>` | *required* | Live field IDs
stored in this column file. |
+ | 164 | **`location`** | `string` | *required* | Location of the column
file. |
+ | 165 | **`file_format`** | `string` | *required* | String file format
name: `avro`, `orc`, or `parquet`. |
+ | 166 | **`file_size_in_bytes`** | `long` | *required* | Total column file
size in bytes. |
+ | 167 | **`key_metadata`** | `binary` | *optional* |
Implementation-specific key metadata for encryption. |
+ | 168 | **`split_offsets`** | `list<169: long>` | *optional* | Split
offsets for the column file. Must be sorted ascending. |
+
+ When a file is added to the dataset, its content entry must set status to
ADDED (1) and store the snapshot ID in which the file was added.
+
+ When a data file's deletion vector or column files are updated, the writer
must record two content entries for the file in the snapshot: a REPLACED (3)
entry for the prior version and a MODIFIED (4) entry for the new, live version.
Both entries store the snapshot ID of the update. A MODIFIED data file entry
must always have a corresponding REPLACED entry.
+
+ When a leaf manifest's `dv` is updated, its content entry must set status
to MODIFIED (4) and store the snapshot ID of the update.
Review Comment:
Duplicates statement below, remove.
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