Issue
The producer delay is too high in the data subscription service. The monitoring data shows that there is a large gap between the numbers of GTIDS in the data subscription service and the source database, and the data subscription service can only parse a small number of transactions per second.
Possible Causes
1. The source database is overloaded.
2. The source database writes data so quickly that the DTS data subscription service cannot parse it all.
3. There are large or complicated transactions written to the source database.
Troubleshooting
1. The source database is overloaded.
Check the source database monitoring metrics. If the write load of the source database is too high, a high subscription delay is to be expected. If the load is normal, further troubleshoot as follows.
2. The source database writes data so quickly that the DTS data subscription service cannot parse it all.
Check the generation speed of source database binlogs. If it exceeds 50 MB/sec, it is very likely that the data parsing capability of the DTS data subscription service has reached the upper limit. In this case, a high subscription delay is to be expected.
If the generation speed of source database binlogs is less than 50 MB/sec, further troubleshoot as follows.
3. There are large or complicated transactions written to the source database.
Check whether there are large transactions being executed in the source database or whether the current table contains large fields such as those of the "JSON" or "BLOB" type.