useful as yet, since its primary source of information is (full) VACUUM,
which makes a concerted effort to get rid of free space before telling
the map about it ... next stop is concurrent VACUUM ...
stub) into the rest of the system. Adopt a cleaner approach to preventing
deadlock in concurrent heap_updates: allow RelationGetBufferForTuple to
select any page of the rel, and put the onus on it to lock both buffers
in a consistent order. Remove no-longer-needed isExtend hack from
API of ReleaseAndReadBuffer.
do anything yet, but it has the necessary connections to initialization
and so forth. Make some gestures towards allowing number of blocks in
a relation to be BlockNumber, ie, unsigned int, rather than signed int.
(I doubt I got all the places that are sloppy about it, yet.) On the
way, replace the hardwired NLOCKS_PER_XACT fudge factor with a GUC
variable.
not being consulted anywhere, so remove it and remove the _mdnblocks()
calls that were used to set it. Change smgrextend interface to pass in
the target block number (ie, current file length) --- the caller always
knows this already, having already done smgrnblocks(), so it's silly to
do it over again inside mdextend. Net result: extension of a file now
takes one lseek(SEEK_END) and a write(), not three lseeks and a write.
(WAL logging for this is not done yet, however.) Clean up a number of really
crufty things that are no longer needed now that DROP behaves nicely. Make
temp table mapper do the right things when drop or rename affecting a temp
table is rolled back. Also, remove "relation modified while in use" error
check, in favor of locking tables at first reference and holding that lock
throughout the statement.
inputs have been converted to newstyle. This should go a long way towards
fixing our portability problems with platforms where char and short
parameters are passed differently from int-width parameters. Still
more to do for the Alpha port however.
whether to do fsync or not, and if so (which should be seldom) just
do the fsync immediately. This way we need not build data structures
in md.c/fd.c for blind writes.
as a shared dirtybit for each shared buffer. The shared dirtybit still
controls writing the buffer, but the local bit controls whether we need
to fsync the buffer's file. This arrangement fixes a bug that allowed
some required fsyncs to be missed, and should improve performance as well.
For more info see my post of same date on pghackers.
Now indexes of pg_class and pg_type are unique indexes
and guarantee the uniqueness of correponding attributes.
heap_create() was changed to take another boolean parameter
which allows to postpone the creation of disk file.
The name of rd_nonameunlinked was changed to rd_unlinked.
It is used generally(not only for noname relations) now.
Requires initdb.
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.
After applying the following patch there remain two
probable buffer overruns detected by Electric Fence during
the regression test.
I'll try find out what causes the remain two ones.
This patch also corrects a typo in smgr.c.
mdunlink() and mdclose() (too !!!) now free MdfdVec for relation
and add it to free list, so it may be re-used for another relation
later.
2. Fix VFD-manager memory leak (found by Massimo ... and me):
mdunlink() has to call FileUnlink() to free allocation for fileName
and add the Vfd slot to the free list.
Tom Lane
Bruce Momjian
Vadim B. Mikheev
Peter Eisentraut
Hiroshi Inoue
Marc G. Fournier