rdblue commented on code in PR #16025:
URL: https://github.com/apache/iceberg/pull/16025#discussion_r4161457764
##########
format/spec.md:
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@@ -731,39 +744,151 @@ The `data_file` struct consists of the following fields:
| _optional_ | _optional_ | _optional_ | **`110 null_value_counts`**
| `map<121: int, 122: long>` |
Map from column id to number of null values in the column |
| _optional_ | _optional_ | _optional_ | **`137 nan_value_counts`**
| `map<138: int, 139: long>` |
Map from column id to number of NaN values in the column |
| _optional_ | _optional_ | | ~~**`111 distinct_counts`**~~
| `map<123: int, 124: long>` |
**Deprecated. Do not write.** |
- | _optional_ | _optional_ | _optional_ | **`125 lower_bounds`**
| `map<126: int, 127: binary>` |
Map from column id to lower bound in the column serialized as binary [1]. Each
value must be less than or equal to all non-null, non-NaN values in the column
for the file [2] |
- | _optional_ | _optional_ | _optional_ | **`128 upper_bounds`**
| `map<129: int, 130: binary>` |
Map from column id to upper bound in the column serialized as binary [1]. Each
value must be greater than or equal to all non-null, non-Nan values in the
column for the file [2] |
+ | _optional_ | _optional_ | _optional_ | **`125 lower_bounds`**
| `map<126: int, 127: binary>` |
Map from column id to lower bound in the column serialized as binary. Each
value must be less than or equal to all non-null, non-NaN values in the column
for the file. See [Field-level Metrics and
Statistics](#field-level-metrics-and-statistics) |
+ | _optional_ | _optional_ | _optional_ | **`128 upper_bounds`**
| `map<129: int, 130: binary>` |
Map from column id to upper bound in the column serialized as binary. Each
value must be greater than or equal to all non-null, non-Nan values in the
column for the file. See [Field-level Metrics and
Statistics](#field-level-metrics-and-statistics) |
| _optional_ | _optional_ | _optional_ | **`131 key_metadata`**
| `binary` |
Implementation-specific key metadata for encryption |
| _optional_ | _optional_ | _optional_ | **`132 split_offsets`**
| `list<133: long>` |
Split offsets for the data file. For example, all row group offsets in a
Parquet file. Must be sorted ascending |
| | _optional_ | _optional_ | **`135 equality_ids`**
| `list<136: int>` |
Field ids used to determine row equality in equality delete files. Required
when `content=2` and should be null otherwise. Fields with ids listed in this
column must be present in the delete file |
- | _optional_ | _optional_ | _optional_ | **`140 sort_order_id`**
| `int` |
ID representing sort order for this file [3]. |
+ | _optional_ | _optional_ | _optional_ | **`140 sort_order_id`**
| `int` |
ID representing sort order for this file [1]. |
| | | _optional_ | **`142 first_row_id`**
| `long` |
The `_row_id` for the first row in the data file. See [First Row ID
Inheritance](#first-row-id-inheritance) |
- | | _optional_ | _optional_ | **`143 referenced_data_file`**
| `string` |
Fully qualified location (URI with FS scheme) of a data file that all deletes
reference [4] |
- | | | _optional_ | **`144 content_offset`**
| `long` |
The offset in the file where the content starts [5] |
- | | | _optional_ | **`145 content_size_in_bytes`**
| `long` |
The length of a referenced content stored in the file; required if
`content_offset` is present [5] |
+ | | _optional_ | _optional_ | **`143 referenced_data_file`**
| `string` |
Fully qualified location (URI with FS scheme) of a data file that all deletes
reference [2] |
+ | | | _optional_ | **`144 content_offset`**
| `long` |
The offset in the file where the content starts [3] |
+ | | | _optional_ | **`145 content_size_in_bytes`**
| `long` |
The length of a referenced content stored in the file; required if
`content_offset` is present [3] |
-The `partition` struct stores the tuple of partition values for each file. Its
type is derived from the partition fields of the partition spec used to write
the manifest file. In v2, the partition struct's field ids must match the ids
from the partition spec.
+ The `partition` struct stores the tuple of partition values for each file.
Its type is derived from the partition fields of the partition spec used to
write the manifest file. In v2, the partition struct's field ids must match the
ids from the partition spec.
-The v4 `content_stats` container struct stores field-level metrics. Unlike the
metrics maps, the type of `content_stats` is based on table metadata, like
schema. Similar to the `partition` struct, the same type is used for all files
tracked in a manifest.
+ Notes:
+
+ 1. If sort order ID is missing or unknown, then the order is assumed to be
unsorted. Only data files and equality delete files should be written with a
non-null order id. [Position deletes](#position-delete-files) are required to
be sorted by file and position, not a table order, and should set sort order id
to null. Readers must ignore sort order id for position delete files.
+ 2. Position delete metadata can use `referenced_data_file` when all
deletes tracked by the entry are in a single data file. Setting the referenced
file is required for deletion vectors.
+ 3. The `content_offset` and `content_size_in_bytes` fields are used to
reference a specific blob for direct access to a deletion vector. For deletion
vectors, these values are required and must exactly match the `offset` and
`length` stored in the Puffin footer for the deletion vector blob.
+ 4. The following field ids are reserved on `data_file`: 141.
+
+=== "v4"
+ The `tracked_file` struct has the following fields:
+
+ | On write | Field id | Name | Type
| Description |
+
|------------|----------|--------------------------|-------------------------------------------------------|-------------|
+ | _required_ | 134 | **`content_type`** | `int` (0: DATA, 3:
DATA_MANIFEST, 4: DELETE_MANIFEST) | Type of content stored in the entry. |
+ | _required_ | 157 | **`format_version`** | `int` (0: PRE-V4, 4:
V4) | Writer format version. |
+ | _required_ | 147 | **`tracking`** | `tracking` struct
| Tracking metadata like status, snapshot ID,
and sequence number. See tracking struct below. |
+ | _required_ | 100 | **`location`** | `string`
| Location of the file. |
+ | _required_ | 101 | **`file_format`** | `string`
| String file format name: `avro`, `orc`, or
`parquet` |
+ | _required_ | 104 | **`file_size_in_bytes`** | `long`
| Total file size in bytes. |
+ | _required_ | 103 | **`record_count`** | `long`
| Number of records in this file. |
+ | _optional_ | 131 | **`key_metadata`** | `binary`
| Implementation-specific key metadata for
encryption. |
+ | _optional_ | 132 | **`split_offsets`** | `list<133: long>`
| Split offsets for the data file. Must be
sorted ascending. |
+ | _optional_ | 141 | **`spec_id`** | `int`
| ID of the partition spec used to partition
the file; null if unpartitioned |
+ | _optional_ | 102 | **`partition`** | `struct<...>`
| Partition data tuple for the file; null if
unpartitioned. |
+ | _optional_ | 140 | **`sort_order_id`** | `int`
| ID representing sort order for this file. If
missing or unknown, the order is assumed to be unsorted. |
+ | _optional_ | 146 | **`content_stats`** | `content_stats`
struct | Field-level stats. See [Content
Stats](#content-stats). |
+ | _optional_ | 150 | **`manifest_info`** | `manifest_info`
struct | Manifest-specific stats. See [Manifest
Info](#manifest-info) |
+ | _optional_ | 148 | **`deletion_vector`** | `deletion_vector`
struct | Row-level deletion vector for a data
file. |
+ | _optional_ | 158 | **`column_files`** | `list<159:
column_file>` | Column files associated with this
file. |
+
+ The `tracking` struct has the following fields:
+
+ | On write | Field id | Name | Type
| Description |
+
|------------|----------|-------------------------------|---------------------------------------------------------------------|-------------|
+ | _required_ | 0 | **`status`** | `int` (0:
EXISTING, 1: ADDED, 2: DELETED, 3: REPLACED, 4: MODIFIED) | Used to track
additions, deletions, replacements, and modifications. |
+ | _optional_ | 1 | **`snapshot_id`** | `long`
| Snapshot ID where the file
was added or deleted. Inherited when null. |
+ | _optional_ | 5 | **`dv_snapshot_id`** | `long`
| Snapshot ID where the
deletion vector or manifest DV last changed. See [Manifest Deletion
Vectors](#manifest-deletion-vectors). |
+ | _optional_ | 8 | **`column_file_snapshot_id`** | `long`
| Snapshot ID where the
latest column file was added. |
+ | _optional_ | 3 | **`sequence_number`** | `long`
| Data sequence number of
the file. Inherited when null. See [Sequence Number
Inheritance](#sequence-number-inheritance). |
+ | _optional_ | 4 | **`file_sequence_number`** | `long`
| File sequence number
indicating when the file was added. Inherited when null. See [Sequence Number
Inheritance](#sequence-number-inheritance). |
+ | _optional_ | 142 | **`first_row_id`** | `long`
| Base row ID for assigning
`_row_id` values. See [First Row ID Inheritance](#first-row-id-inheritance). |
+ | _optional_ | 6 | **`deleted_positions`** | `binary`
| Positions deleted via
manifest DV in the `dv_snapshot_id` snapshot. See [Manifest Deletion
Vectors](#manifest-deletion-vectors). |
+ | _optional_ | 7 | **`replaced_positions`** | `binary`
| Positions replaced via
manifest DV in the `dv_snapshot_id` snapshot. See [Manifest Deletion
Vectors](#manifest-deletion-vectors). |
+
+ The `deletion_vector` struct has the following fields:
+
+ | On write | Field id | Name | Type | Description |
+ |------------|----------|---------------------|----------|-------------|
+ | _required_ | 155 | **`location`** | `string` | Location of the
file that stores the DV. |
+ | _required_ | 144 | **`offset`** | `long` | Offset in the
file where the content starts. |
+ | _required_ | 145 | **`size_in_bytes`** | `long` | Length of the
referenced content stored in the file. |
+ | _required_ | 156 | **`cardinality`** | `long` | Number of set
bits (deleted rows) in the deletion vector. |
+ | _optional_ | 149 | **`key_metadata`** | `binary` | Key metadata
for encryption; specific to the encryption scheme. |
+
+ ##### Manifest Info
+
+ The `manifest_info` struct has the following fields:
+
+ | On write | Field id | Name | Type |
Description |
+
|------------|----------|----------------------------|----------|-------------|
+ | _optional_ | 522 | **`dv`** | `binary` |
Positions in the referenced leaf manifest that are not live. See [Manifest
Deletion Vectors](#manifest-deletion-vectors). |
+ | _required_ | 504 | **`added_files_count`** | `int` | Count of
entries with status ADDED in the manifest. |
+ | _required_ | 505 | **`existing_files_count`** | `int` | Count of
entries with status EXISTING in the manifest. |
+ | _required_ | 525 | **`modified_files_count`** | `int` | Count of
entries with status MODIFIED in the manifest. |
+ | _required_ | 506 | **`deleted_files_count`** | `int` | Count of
entries with status DELETED in the manifest. |
+ | _required_ | 523 | **`replaced_files_count`** | `int` | Count of
entries with status REPLACED in the manifest. |
+ | _required_ | 512 | **`added_rows_count`** | `long` | Total
number of rows in ADDED entries. |
+ | _required_ | 513 | **`existing_rows_count`** | `long` | Total
number of rows in EXISTING entries. |
+ | _required_ | 526 | **`modified_rows_count`** | `long` | Total
number of rows in MODIFIED entries. |
+ | _required_ | 514 | **`deleted_rows_count`** | `long` | Total
number of rows in DELETED entries. |
+ | _required_ | 524 | **`replaced_rows_count`** | `long` | Total
number of rows in REPLACED entries. |
+ | _required_ | 516 | **`min_sequence_number`** | `long` | Minimum
data sequence number of all live entries in the manifest. |
+
+ The `column_file` struct has the following fields:
+
+ | On write | Field id | Name | Type |
Description |
+
|------------|----------|--------------------------|------------------|-------------|
+ | _required_ | 161 | **`format_version`** | `int` (4: V4) |
Format version of this column file. |
+ | _required_ | 162 | **`field_ids`** | `list<163: int>` |
Live field IDs stored in this column file. |
+ | _required_ | 164 | **`location`** | `string` |
Location of the column file. |
+ | _required_ | 165 | **`file_format`** | `string` |
String file format name: `avro`, `orc`, or `parquet`. |
+ | _required_ | 166 | **`file_size_in_bytes`** | `long` |
Total column file size in bytes. |
+ | _optional_ | 167 | **`key_metadata`** | `binary` |
Implementation-specific key metadata for encryption. |
+
+ **Tracked File Requirements**
+
+ - `deletion_vector.offset` and `deletion_vector.size_in_bytes` must
exactly match the `offset` and `length` stored in the Puffin footer for the
deletion vector blob.
+ - A leaf manifest written in v4 may only contain data files.
+ - Row-level deletes may only be written in v4 as deletion vectors in the
data file's `deletion_vector`.
+ - Delete files from pre-v4 tables are valid in upgraded tables and are
tracked in delete manifests written before the upgrade.
+ - A root manifest may reference v1-v3 manifests; a referenced v1-v3 leaf
manifest must have `format_version` PRE-V4.
+ - Other v4 tracked files must have `format_version` V4.
+ - `manifest_info` must be set if and only if the tracked file is a
manifest.
+ - For manifests, `manifest_info.added_files_count`,
`existing_files_count`, `deleted_files_count`, `replaced_files_count`, and
`modified_files_count` must sum to `record_count`.
+ - `deletion_vector` may only be set if the tracked file is a data file.
+ - `column_files` may only be set if the tracked file is a data file or a
v4 leaf manifest.
+ - `tracking.deleted_positions` and `tracking.replaced_positions` may only
be set if the tracked file is a manifest.
+ - `tracking.snapshot_id` and `tracking.sequence_number` are required for
the tracked file in the root manifest.
+ - Writers should not write a null `tracking.snapshot_id`.
+ - For manifests, `tracking.sequence_number` must equal
`tracking.file_sequence_number`.
+ - For manifests, `spec_id` must be set to the `spec_id` of the manifest's
entries if all entries have the same `spec_id`, and must be null otherwise.
+ - `tracking.dv_snapshot_id` may only be set if `deletion_vector` or
`manifest_info.dv` is set.
+ - `tracking.column_file_snapshot_id` may only be set if `column_files` is
set.
+
+ When a file is added to the dataset, its tracked file must set status to
ADDED 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 a MODIFIED entry for the live version and must mark the prior
version as replaced with a REPLACED entry or in a [manifest deletion
vector](#manifest-deletion-vectors). When using a manifest deletion vector, the
writer must set the position in the leaf manifest's
`tracking.replaced_positions` and `manifest_info.dv`. The resulting entries'
`dv_snapshot_id` or `column_file_snapshot_id` must record the snapshot in which
their deletion vector, manifest deletion vector, or column files last changed.
+
+ When a file is deleted from the dataset, the deletion must be recorded in
the snapshot that deletes the file with a DELETED entry that stores the
snapshot ID in which the file was deleted or, for an entry in a leaf manifest,
alternatively by setting its position in the leaf manifest's
`tracking.deleted_positions` and `manifest_info.dv` and updating
`tracking.dv_snapshot_id` to the new snapshot ID.
+
+ A leaf manifest whose `manifest_info.dv` changed must have status
MODIFIED. `tracking.deleted_positions` and `tracking.replaced_positions` should
only be set in the snapshot that changes `manifest_info.dv`.
+
+A file that is no longer live 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
snapshot root.
+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. In v4, a MODIFIED entry that adds a
column file also inherits its data sequence number.
Review Comment:
We probably want a combine section on inheritance for this content. We can
also drop the "v2 adds" part. We can just state toward the bottom that this
doesn't apply to v1, which doesn't support inheritance or have sequence numbers.
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