DM cluster observability with large number of empty tables.

[kennedy8312]

What did you do?

Migrate 100k empty tables from MySQL 8.0.32 to a TiDB cluster v7.6.

What did you expect to see?

Migration progress from command output, dm-worker.log and grafana.

What did you see instead?

The progress was always 0. I guess it is due to the current progress estimation is calculated based on data bytes only?

1. Command output "load": { "finishedBytes": "0", "totalBytes": "0", "progress": "0.00 %", "metaBinlog": "(binlog.000005, 157)", "metaBinlogGTID": "", "bps": "0" },

dm-worker.log [2023/12/15 12:23:23.620 +00:00] [INFO] [lightning.go:628] ["progress status of lightning"] [task=all1M] [unit=lightning-load] [finished_bytes=0] [total_bytes=0] [progress="0.00 %"] ["current speed (bytes / seconds)"=0] 3. Granafa monitor

Versions of the cluster

DM version (run dmctl -V or dm-worker -V or dm-master -V):

(paste DM version here, and you must ensure versions of dmctl, DM-worker and DM-master are same)

Upstream MySQL/MariaDB server version:

(paste upstream MySQL/MariaDB server version here)

Downstream TiDB cluster version (execute SELECT tidb_version(); in a MySQL client):

(paste TiDB cluster version here)

How did you deploy DM: tiup or manually?

(leave TiUP or manually here)

Other interesting information (system version, hardware config, etc):

>
>

current status of DM cluster (execute query-status <task-name> in dmctl)

(paste current status of DM cluster here)

[kennedy8312]

candidate_1m

[lance6716]

You can check downstream TiDB cluster's grafana / SHOW PROCESSLIST to see what's going on. I guess DM is creating table in downstream and this action is a bit slow for TiDB.

[kennedy8312]

Yes, it is creating tables in the downtream TiDB cluster.

[fubinzh]

/severity moderate