granted the lock when awakened; the signal now only means that the lock
is potentially available. The waiting process must retry its attempt
to get the lock when it gets to run. This allows the lock releasing
process to re-acquire the lock later in its timeslice. Since LWLocks
are usually held for short periods, it is possible for a process to
acquire and release the same lock many times in a timeslice. The old
spinlock-based implementation of these locks allowed for that; but the
original coding of LWLock would force a process swap for each acquisition
if there was any contention. Although this approach reopens the door to
process starvation (a waiter might repeatedly fail to get the lock),
the odds of that being a big problem seem low, and the performance cost
of the previous approach is considerable.
to the client before closing the connection. Before 7.2 this was done
correctly, but new code would simply close the connection with no report
to the client.
a get on a bytea value the code was running the raw value from the server
through character set conversion, which if the character set was SQL_ASCII
would cause all 8bit characters to become ?'s.
Fixes time zone problems introduced by Thomas' implementation of
TIMESTAMP WITHOUT TIME ZONE which caused the behavior of the previously
appropriate routine, timestamp_date(), to change for the worse in this
context.
Disallow CREATE INDEX on system catalogs, non-tables (views, sequences, etc).
Disallow CREATE/DROP TRIGGER on system catalogs, non-tables.
Disallow ALTER TABLE ADD/DROP CONSTRAINT on system catalogs.
Disallow FOREIGN KEY reference to non-table.
None of these things can actually work in the present system structure,
but the code was letting them pass without complaint.
macros, but only at explicit CHECK_FOR_INTERRUPTS() calls. Not clear
whether overenthusiastic acceptance of interrupts accounts for any real
bugs, but it definitely seems risky and unnecessary.
to insert the same key into a supposedly unique index. The bug is of
low probability, and may not explain any of the recent reports of
duplicated rows; but a bug is a bug.
