The below mentioned script helps us to find the number of Undelivered Commands from the publisher.
Courtesy: http://www.sqlsoldier.com/wp/sqlserver/countingunreplicatedcommandsandtransactions

With MaxXact (ServerName, PublisherDBID, XactSeqNo)
 As (Select S.name, DA.publisher_database_id, max(H.xact_seqno)
 From distribution.dbo.MSdistribution_history H with(nolock)
 Inner Join distribution.dbo.MSdistribution_agents DA with(nolock)
 On DA.id = H.agent_id
 Inner Join master.sys.servers S with(nolock)
 On S.server_id = DA.subscriber_id
 Group By S.name, DA.publisher_database_id)
 Select MX.ServerName, MX.PublisherDBID, COUNT(*)
 As CommandsNotReplicated
 From distribution.dbo.MSrepl_commands C with(nolock)
 Right Join MaxXact MX On
 MX.XactSeqNo < C.xact_seqno And
 MX.PublisherDBID = C.publisher_database_id
 Group By MX.ServerName, MX.PublisherDBID;

Tagged: Microsoft SQL Server, Replication, SQL, Undelivered Commands