Help needed on Fixing replication latency issues

Question

Hi Team,
Good day!!!
I am new to replication setup and I am working on the issues with replication latency.
Can you please provide us your experience and expertise on fixing and troubleshooting replication issues.
Below are some queries on that,
1) How to check the replication errors?
2) how to find out the replication latency?
3) What are the steps to fix the replication latency?
4) how to teoubleshoot the issues coming on replication latency?
Awaiting your valuable response and replies.
Thanks in advance,
Sarvan.N

Answer 1

Hi Sarvan,
Firstly, usually, we check replication errors via the Replication Monitor or by viewing replication agent job history. Besides the two methods, we can also check replication errors from the SQL Server error log and so on. For more details,
please review this
article.
Secondly, based on my research, the latency issues always occur in Transactional Replication.  We can check that if there are latency issues by using Replication Monitor as well as Transact-SQL commands. Below is an example that posts a tracer token
record and uses the returned ID of the posted tracer token to view latency information. Refer to :
Measure Latency and Validate Connections for Transactional Replication.
DECLARE @publication AS sysname;
DECLARE @tokenID AS int;
SET @publication = N'AdvWorksProductTran';
USE [AdventureWorks2012]
-- Insert a new tracer token in the publication database.
EXEC sys.sp_posttracertoken
@publication = @publication,
@tracer_token_id = @tokenID OUTPUT;
SELECT 'The ID of the new tracer token is ''' +
CONVERT(varchar,@tokenID) + '''.'
GO
-- Wait 10 seconds for the token to make it to the Subscriber.
WAITFOR DELAY '00:00:10';
GO
-- Get latency information for the last inserted token.
DECLARE @publication AS sysname;
DECLARE @tokenID AS int;
SET @publication = N'AdvWorksProductTran';
CREATE TABLE #tokens (tracer_id int, publisher_commit datetime)
-- Return tracer token information to a temp table.
INSERT #tokens (tracer_id, publisher_commit)
EXEC sys.sp_helptracertokens @publication = @publication;
SET @tokenID = (SELECT TOP 1 tracer_id FROM #tokens
ORDER BY publisher_commit DESC)
DROP TABLE #tokens
-- Get history for the tracer token.
EXEC sys.sp_helptracertokenhistory
@publication = @publication,
@tracer_id = @tokenID;
GO
Thirdly, transactional replication latency issues could be caused by many factors, such as network traffic or bandwidth constraints, transactional load on the publisher, system resources, blocking/locking issues and so on. I recommend you troubleshoot latency
issues referring to the following blog.
http://blogs.msdn.com/b/repltalk/archive/2010/02/21/transactional-replication-conversations.aspx
Thanks,
Lydia Zhang