deadlock_timeout (integer)
This is the amount of time to wait on a lock
before checking to see if there is a deadlock condition. The
check for deadlock is relatively expensive, so the server doesn't run
it every time it waits for a lock. We optimistically assume
that deadlocks are not common in production applications and
just wait on the lock for a while before checking for a
deadlock. Increasing this value reduces the amount of time
wasted in needless deadlock checks, but slows down reporting of
real deadlock errors.
If this value is specified without units, it is taken as milliseconds.
The default is one second (1s),
which is probably about the smallest value you would want in
practice. On a heavily loaded server you might want to raise it.
Ideally the setting should exceed your typical transaction time,
so as to improve the odds that a lock will be released before
the waiter decides to check for deadlock. Only superusers can change
this setting.
When log_lock_waits is set,
this parameter also determines the amount of time to wait before
a log message is issued about the lock wait. If you are trying
to investigate locking delays you might want to set a shorter than
normal deadlock_timeout.
max_locks_per_transaction (integer)
The shared lock table tracks locks on
max_locks_per_transaction * (max_connections + max_prepared_transactions) objects (e.g., tables);
hence, no more than this many distinct objects can be locked at
any one time. This parameter controls the average number of object
locks allocated for each transaction; individual transactions
can lock more objects as long as the locks of all transactions
fit in the lock table. This is not the number of
rows that can be locked; that value is unlimited. The default,
64, has historically proven sufficient, but you might need to
raise this value if you have queries that touch many different
tables in a single transaction, e.g., query of a parent table with
many children. This parameter can only be set at server start.
When running a standby server, you must set this parameter to the same or higher value than on the master server. Otherwise, queries will not be allowed in the standby server.