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The following commit(s) were added to refs/heads/trunk by this push:
new be6feb2f636 KAFKA-20354: Add missing Control Batch types in
documentation (#21866)
be6feb2f636 is described below
commit be6feb2f6363e6e61625a09058dc74b7309451a9
Author: Federico Valeri <[email protected]>
AuthorDate: Fri Apr 10 10:28:50 2026 +0200
KAFKA-20354: Add missing Control Batch types in documentation (#21866)
This patch adds missing Control Batch types in the documentation.
Reviewers: Luke Chen <[email protected]>, Andrew Schofield
<[email protected]>, Mickael Maison <[email protected]>
---------
Signed-off-by: Federico Valeri <[email protected]>
---
docs/implementation/message-format.md | 55 ++++++++++++++++++++++++++++++++---
1 file changed, 51 insertions(+), 4 deletions(-)
diff --git a/docs/implementation/message-format.md
b/docs/implementation/message-format.md
index 29078b759c4..2a9ced5c074 100644
--- a/docs/implementation/message-format.md
+++ b/docs/implementation/message-format.md
@@ -72,16 +72,63 @@ Compaction may also modify the baseTimestamp if the record
batch contains record
### Control Batches
-A control batch contains a single record called the control record. Control
records should not be passed on to applications. Instead, they are used by
consumers to filter out aborted transactional messages.
+A control batch contains a single record called the control record. Control
records should not be returned to applications. Instead, they are used by
consumers to filter out aborted transactional messages, and by the KRaft
implementation for its protocol metadata.
-The key of a control record conforms to the following schema:
+The key of a control record conforms to the following schema:
```text
version: int16 (current version is 0)
-type: int16 (0 indicates an abort marker, 1 indicates a commit)
+type: int16 (the control record types are in the table below)
```
-The schema for the value of a control record is dependent on the type. The
value is opaque to clients.
+The following control record types are currently defined for regular topics:
+
+<table>
+<tr>
+<th>
+
+Type
+</th>
+<th>
+
+Name
+</th>
+<th>
+
+Description
+</th>
+</tr>
+<tr>
+<td>
+
+0
+</td>
+<td>
+
+ABORT
+</td>
+<td>
+
+Marks a transaction as aborted.
+</td>
+</tr>
+<tr>
+<td>
+
+1
+</td>
+<td>
+
+COMMIT
+</td>
+<td>
+
+Marks a transaction as committed.
+</td>
+</tr>
+</table>
+
+Types 0 and 1 are used as end-of-transaction markers for the transactional
messaging protocol. Types 2 through 6 are used internally by the KRaft
consensus protocol. The schema of the value in the control record is dependent
on the type. The value is opaque to clients.
## Record
