in or_normalize, remove detection of duplicate subexpressions (since it's
highly unlikely to be worth the amount of time it takes), and introduce
a dnfify() entry point so that unintelligible backwards logic in UNION
processing can be eliminated.  This is just an intermediate step ---
next thing is to look at not forcing the qual into CNF form when it would
be better off in DNF form.

and pg_server_to_client.  Eliminate copy.c's restriction on the length
of a single attribute.

arbitrarily long strings, and frontends should cope gracefully.  Goes
along with long query and long error message changes...

This change seems necessary in conjunction with long queries, and it
cleans up some bogosity in connection with long EXPLAIN texts anyway.
Note that current libpq will accept any length error message (at least
until it runs out of memory); prior versions have a limit of 8K, but
will cleanly discard excess error text, so there shouldn't be any
big compatibility problems with old clients.

transaction abort --- before it only worked if there was exactly one level
of allocation context stacked in the blank portal.  Now it does the right
thing for any depth, including zero...

expired messages before concluding that we really have buffer overflow.

cluttering the log file...

was rejecting negative attnums as bogus, which of course they are not.
Add code to get_attdisbursion to produce a useful value for OID attribute,
since VACUUM does not store stats for system attributes.
Also, repair bug that's been in eqjoinsel for a long time: it was taking
the max of the two columns' disbursions, whereas it should use the min.

don't read man pages...

when reach end of pattern before end of text.  Improve code comments.

space consumption in pull_args, and avoid doing the full CNF transform on
operands of operator clauses, where it's really not particularly helpful.
This answers the TODO item about large numbers of OR clauses, at least
partially.  I was able to do a ten-thousand-OR-clause query with about
20Mb memory consumption ... it took an obscenely long time, but it worked...

corrects flex myinput() routine so that it doesn't assume there is only
one bufferload of data.  We still have the issue of getting rid of
YY_USES_REJECT so that the scanner can cope with tokens larger than its
initial buffer size.

psql.c seems clean of query length restrictions now.

before comparison; if fields being joined are different widths then hashing
will yield wrong answer.  Also, remove hashjoinable mark from all uses of
array_eq, because array structures may have padding bytes between elements
and the pad bytes are of uncertain content.  This could be revisited if
array code is cleaned up.
Modify opr_sanity regress test to complain if array_eq operator is marked
hashjoinable.

offended my aesthestic sensibility that there was so much unreadable code
doing so little.  Rewritten code is about half the size, faster, and
(I hope) much more intelligible.

current transaction) are not flushed by shared-cache-inval reset message.
SI reset actually works now, for probably the first time in a long time.
I was able to run initdb and regression tests with a 16-element SI message
array, with a lot of NOTICE: cache state reset messages but no crashes.

system tables, but actually there are only 6 --- see RelationInitialize.
Kinda makes you wonder how long ago this code was last executed...

automatically create the file, except during bootstrap mode where that
seems to be necessary.

We can't support these properly, since once the relation's physical files
are unlinked, there's no way to roll back the transaction.  I suppose
we could postpone the unlink till transaction commit, but then what of
BEGIN; DROP TABLE foo; CREATE TABLE foo; ?
The code does allow dropping a table/index created in the current
transaction block, however, since the post-abort state would be that
the table doesn't exist anyway.

real name before doing lookup.  We only want to index temp tables by their
real names in the relcache, to ensure there's not more than one relcache
entry for them.

to be deleted.

pg_class tuple during ALTER TABLE ADD COLUMN.

has positive refcount, it is rebuilt from pg_class data.  This ensures
that relcache entries will track changes made by other backends.  Formerly,
a shared inval report would just be ignored if it happened to arrive while
the relcache entry was in use.  Also, fix relcache to reset ref counts
to zero during transaction abort.  Finally, change LockRelation() so that
it checks for shared inval reports after obtaining the lock.  In this way,
once any kind of lock has been obtained on a rel, we can trust the relcache
entry to be up-to-date.

the SInval spinlock while it is calling the passed invalFunction or
resetFunction.  This is necessary to avoid deadlock with lmgr change;
InvalidateSharedInvalid can be called recursively now.  It should be
a good performance improvement anyway --- holding a spinlock for more
than a very short interval is a no-no.

istm that this would be a job for configure.
Most modern OSes actually use perl5 by default ;)

insight that RelationFlushRelation ought to invoke smgrclose, and that the
way to make that work is to ensure that mdclose doesn't fail if the relation
is already closed (or unlinked, if we are looking at a DROP TABLE).  While
I was testing that, I was able to identify several problems that we had
with multiple-segment relations.  The system is now able to do initdb and
pass the regression tests with a very small segment size (I had it set to
64Kb per segment for testing).  I don't believe that ever worked before.
File descriptor leaks seem to be gone too.
I have partially addressed the concerns we had about mdtruncate(), too.
On a Win32 or NFS filesystem it is not possible to unlink a file that
another backend is holding open, so what md.c now does is to truncate
unwanted files to zero length before trying to unlink them.  The other
backends will be forced to close their open files by relation cache
invalidation --- but I think it would take considerable work to make
that happen before vacuum truncates the relation rather than after.
Leaving zero-length files lying around seems a usable compromise.