Begin Prepare (logical replication)

Description

Logical replication Begin Prepare format. Identifies the message as the beginning of a prepared transaction message.

Layer

Logical replication payload; distinct from the frontend/backend message envelope

First field

Byte1('b')

Usage

Begin Prepare

Protocol context

This section describes the detailed format of each logical replication message. These messages are either returned by the replication slot SQL interface or are sent by a walsender. In the case of a walsender, they are encapsulated inside replication protocol WAL messages as described in Section 54.4 , and generally obey the same message flow as physical replication. The following messages (Stream Start, Stream Stop, Stream Commit, and Stream Abort) are available since protocol version 2. The following messages (Begin Prepare, Prepare, Commit Prepared, Rollback Prepared, Stream Prepare) are available since protocol version 3. The following message parts are shared by the above messages.

Related entries

• Streaming replication protocol
• Logical Decoding Plugins

Documentation and source

• PostgreSQL 18 English manual

Compare versions

PostgreSQL 14 → 15: added.

--- PostgreSQL 14
+++ PostgreSQL 15
@@ -1 +1,29 @@
-Not recorded in this version
+{
+  "fields": [
+    {
+      "description": "Identifies the message as the beginning of a prepared transaction message.",
+      "format": "Byte1('b')"
+    },
+    {
+      "description": "The LSN of the prepare.",
+      "format": "Int64 (XLogRecPtr)"
+    },
+    {
+      "description": "The end LSN of the prepared transaction.",
+      "format": "Int64 (XLogRecPtr)"
+    },
+    {
+      "description": "Prepare timestamp of the transaction. The value is in number of microseconds since PostgreSQL epoch (2000-01-01).",
+      "format": "Int64 (TimestampTz)"
+    },
+    {
+      "description": "Xid of the transaction.",
+      "format": "Int32 (TransactionId)"
+    },
+    {
+      "description": "The user defined GID of the prepared transaction.",
+      "format": "String"
+    }
+  ],
+  "layer": "logical replication"
+}

Compares recorded interfaces and attributes. Source fingerprints and build metadata are excluded; an absent sample is not proof of the introduction or removal release.

Related entries

• Begin (logical replication)
• Commit (logical replication)
• Commit Prepared (logical replication)
• Delete (logical replication)
• Insert (logical replication)
• Message (logical replication)
• Origin (logical replication)
• Prepare (logical replication)
• Relation (logical replication)
• Rollback Prepared (logical replication)
• Stream Abort (logical replication)
• Stream Commit (logical replication)