Allowing VACUUM to time out when waiting for locks?

We have a frequently updated (peak > 5/sec) table with about 1000 rows.

We run VACCUM FULL on this table every 5 minutes.

The regular updates are not long in duration, and the vacuum is fast, so they
do not produce noticeable delays.

When we run a pg_dump on the database:

- the dump takes a long standing AccessShareLock lock on this table
(the database is large, and the table is locked for the duration).

- the regular updates run quite happily

- the VACUUM FULL comes along and asks for a AccessExclusiveLock
(which is not granted due to PG_DUMP).

- the regular updates hang until the dump completes

Is it possible to set up a vacuum to fail if a lock is not granted in
a limited period of time (eg. 1 minute)?

We could use lock files to synchronize our dumps with our vacuums, but
were hoping for a way of managing this within the DB so that ad-hoc dumps
will not cause a problem.

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