problems about updating a table and cluster this table at the same time

Hello,

I work on a large database. I make use of cron job to
cluster certain database table periodically.

I found when updating a table and clusterdb cron job
happens to run at exactly the same time clustering
that table, then both updating and clustering stuck.
Database server hault. This cause my system hault.

I tried to lock that table using 'lock tableName'
command before updating that table, I run 'clusterdb
-t tableName dbName', I found clusterdb ignore the
fact that the table is locked and go ahead finishing
cluster job.

So how can I protect the table when I update it to
avoid cluster cron job interrupt the update?

Any suggestion will be greatly appreciated!

jing

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