postgres.git / summary / log / commit / refs

commit    9f1cf97bb5387a6243c8a6c9725616ef7447962e
Author:   Alvaro Herrera <alvherre@alvh.no-ip.org>
Date:     Thu Sep 10 22:37:02 2020 +0000

    Print WAL logical message contents in pg_waldump
    
    This helps debuggability when looking at WAL streams containing logical
    messages.
    
    Author: Ashutosh Bapat <ashutosh.bapat@2ndquadrant.com>
    Reviewed-by: Álvaro Herrera <alvherre@alvh.no-ip.org>
    Discussion: https://postgr.es/m/CAExHW5sWx49rKmXbg5H1Xc1t+nRv9PaYKQmgw82HPt6vWDVmDg@mail.gmail.com


 src/backend/access/rmgrdesc/logicalmsgdesc.c | 17 ++++++++++++++---
 src/backend/replication/logical/message.c    |  1 +
 src/include/replication/message.h            |  5 ++---
 3 files changed, 17 insertions(+), 6 deletions(-)

diff --git a/src/backend/access/rmgrdesc/logicalmsgdesc.c b/src/backend/access/rmgrdesc/logicalmsgdesc.c
index bff298c9287..83ab93a24be 100644
--- a/src/backend/access/rmgrdesc/logicalmsgdesc.c
+++ b/src/backend/access/rmgrdesc/logicalmsgdesc.c
@@ -24,10 +24,21 @@ logicalmsg_desc(StringInfo buf, XLogReaderState *record)
 	if (info == XLOG_LOGICAL_MESSAGE)
 	{
 		xl_logical_message *xlrec = (xl_logical_message *) rec;
+		char	   *prefix = xlrec->message;
+		char	   *message = xlrec->message + xlrec->prefix_size;
+		char	   *sep = "";
 
-		appendStringInfo(buf, "%s message size %zu bytes",
-						 xlrec->transactional ? "transactional" : "nontransactional",
-						 xlrec->message_size);
+		Assert(prefix[xlrec->prefix_size] != '\0');
+
+		appendStringInfo(buf, "%s, prefix \"%s\"; payload (%zu bytes): ",
+						 xlrec->transactional ? "transactional" : "non-transactional",
+						 prefix, xlrec->message_size);
+		/* Write message payload as a series of hex bytes */
+		for (int cnt = 0; cnt < xlrec->message_size; cnt++)
+		{
+			appendStringInfo(buf, "%s%02X", sep, (unsigned char) message[cnt]);
+			sep = " ";
+		}
 	}
 }
 
diff --git a/src/backend/replication/logical/message.c b/src/backend/replication/logical/message.c
index db33cbe5a7a..bd4b08543e6 100644
--- a/src/backend/replication/logical/message.c
+++ b/src/backend/replication/logical/message.c
@@ -59,6 +59,7 @@ LogLogicalMessage(const char *prefix, const char *message, size_t size,
 
 	xlrec.dbId = MyDatabaseId;
 	xlrec.transactional = transactional;
+	/* trailing zero is critical; see logicalmsg_desc */
 	xlrec.prefix_size = strlen(prefix) + 1;
 	xlrec.message_size = size;
 
diff --git a/src/include/replication/message.h b/src/include/replication/message.h
index 937addde485..e97891ebcaf 100644
--- a/src/include/replication/message.h
+++ b/src/include/replication/message.h
@@ -23,9 +23,8 @@ typedef struct xl_logical_message
 	bool		transactional;	/* is message transactional? */
 	Size		prefix_size;	/* length of prefix */
 	Size		message_size;	/* size of the message */
-	char		message[FLEXIBLE_ARRAY_MEMBER]; /* message including the null
-												 * terminated prefix of length
-												 * prefix_size */
+	/* payload, including null-terminated prefix of length prefix_size */
+	char		message[FLEXIBLE_ARRAY_MEMBER];
 } xl_logical_message;
 
 #define SizeOfLogicalMessage	(offsetof(xl_logical_message, message))


[parent: 58c6feccfae1]