in PITR scenarios. We now WAL-log the replacement of old XIDs with
FrozenTransactionId, so that such replacement is guaranteed to propagate to
PITR slave databases. Also, rather than relying on hint-bit updates to be
preserved, pg_clog is not truncated until all instances of an XID are known to
have been replaced by FrozenTransactionId. Add new GUC variables and
pg_autovacuum columns to allow management of the freezing policy, so that
users can trade off the size of pg_clog against the amount of freezing work
done. Revise the already-existing code that forces autovacuum of tables
approaching the wraparound point to make it more bulletproof; also, revise the
autovacuum logic so that anti-wraparound vacuuming is done per-table rather
than per-database. initdb forced because of changes in pg_class, pg_database,
and pg_autovacuum catalogs. Heikki Linnakangas, Simon Riggs, and Tom Lane.
tuples with less header overhead than a regular HeapTuple, per my
recent proposal. Teach TupleTableSlot code how to deal with these.
As proof of concept, change tuplestore.c to store MinimalTuples instead
of HeapTuples. Future patches will expand the concept to other places
where it is useful.
(relpages/reltuples). To do this, create formal support in heapam.c for
"overwrite" tuple updates (including xlog replay capability) and use that
instead of the ad-hoc overwrites we'd been using in VACUUM and CREATE INDEX.
Take the responsibility for updating stats during CREATE INDEX out of the
individual index AMs, and do it where it belongs, in catalog/index.c. Aside
from being more modular, this avoids having to update the same tuple twice in
some paths through CREATE INDEX. It's probably not measurably faster, but
for sure it's a lot cleaner than before.
comment line where output as too long, and update typedefs for /lib
directory. Also fix case where identifiers were used as variable names
in the backend, but as typedefs in ecpg (favor the backend for
indenting).
Backpatch to 8.1.X.
on a page, as suggested by ITAGAKI Takahiro. Also, change a few places
that were using some other estimates of max-items-per-page to consistently
use MaxOffsetNumber. This is conservatively large --- we could have used
the new MaxHeapTuplesPerPage macro, or a similar one for index tuples ---
but those places are simply declaring a fixed-size buffer and assuming it
will work, rather than actively testing for overrun. It seems safer to
size these buffers in a way that can't overflow even if the page is
corrupt.
insufficient paranoia in code that follows t_ctid links. (We must do both
because even with VACUUM doing it properly, the intermediate state with
a dangling t_ctid link is visible concurrently during lazy VACUUM, and
could be seen afterwards if either type of VACUUM crashes partway through.)
Also try to improve documentation about what's going on. Patch is a bit
bulky because passing the XMAX information around required changing the
APIs of some low-level heapam.c routines, but it's not conceptually very
complicated. Per trouble report from Teodor and subsequent analysis.
This needs to be back-patched, but I'll do that after 8.1 beta is out.
transaction IDs, rather than like subtrans; in particular, the information
now survives a database restart. Per previous discussion, this is
essential for PITR log shipping and for 2PC.
to eliminate unnecessary deadlocks. This commit adds SELECT ... FOR SHARE
paralleling SELECT ... FOR UPDATE. The implementation uses a new SLRU
data structure (managed much like pg_subtrans) to represent multiple-
transaction-ID sets. When more than one transaction is holding a shared
lock on a particular row, we create a MultiXactId representing that set
of transactions and store its ID in the row's XMAX. This scheme allows
an effectively unlimited number of row locks, just as we did before,
while not costing any extra overhead except when a shared lock actually
has to be shared. Still TODO: use the regular lock manager to control
the grant order when multiple backends are waiting for a row lock.
Alvaro Herrera and Tom Lane.
transaction rollback via UNDO but I think that's highly unlikely to
happen, so we may as well remove the stubs. (Someday we ought to
rip out the stub xxx_undo routines, too.) Per Alvaro.
Also performed an initial run through of upgrading our Copyright date to
extend to 2005 ... first run here was very simple ... change everything
where: grep 1996-2004 && the word 'Copyright' ... scanned through the
generated list with 'less' first, and after, to make sure that I only
picked up the right entries ...
number of active subtransaction XIDs in each backend's PGPROC entry,
and use this to avoid expensive probes into pg_subtrans during
TransactionIdIsInProgress. Extend EOXactCallback API to allow add-on
modules to get control at subxact start/end. (This is deliberately
not compatible with the former API, since any uses of that API probably
need manual review anyway.) Add basic reference documentation for
SAVEPOINT and related commands. Minor other cleanups to check off some
of the open issues for subtransactions.
Alvaro Herrera and Tom Lane.
shift support code into heapam.c accordingly. This is in service of
soon-to-be-committed ALTER TABLE SET TABLESPACE code that will want to
use this same record type for both heaps and indexes.
Theoretically I should have forced initdb for this, but in practice there
is no change in xlog contents because CVS tip will never really emit this
record type anyhow...
performance front, but with feature freeze upon us I think it's time to
drive a stake in the ground and say that this will be in 7.5.
Alvaro Herrera, with some help from Tom Lane.
results with tuples as ordinary varlena Datums. This commit does not
in itself do much for us, except eliminate the horrid memory leak
associated with evaluation of whole-row variables. However, it lays the
groundwork for allowing composite types as table columns, and perhaps
some other useful features as well. Per my proposal of a few days ago.
tuptoaster.c --- fields that are compressed in-line are not a reason
to invoke the toaster. Along the way, add a couple more htup.h macros
to eliminate confusing negated tests, and get rid of the already
vestigial TUPLE_TOASTER_ACTIVE symbol.
VACUUM FULL tuple moves. Store full-width t_infomask in WAL, rather
than storing low 8 bits and expecting to be able to reconstruct upper
bits. While at it, remove redundant t_oid field from WAL headers
(the OID, if present, is now recorded in the data portion of the tuple).
WAL version number bumped --- this does not force an initdb, you can
instead run pg_resetxlog after a clean shutdown of the old postmaster.
(overlaying low byte of page size) and add HEAP_HASOID bit to t_infomask,
per earlier discussion. Simplify scheme for overlaying fields in tuple
header (no need for cmax to live in more than one place). Don't try to
clear infomask status bits in tqual.c --- not safe to do it there. Don't
try to force output table of a SELECT INTO to have OIDs, either. Get rid
of unnecessarily complex three-state scheme for TupleDesc.tdhasoids, which
has already caused one recent failure. Improve documentation.
width types and varlena types, since with the introduction of CSTRING as
a more-or-less-real type, these concepts aren't identical. I've tried to
use varlena consistently to denote datatypes with typlen = -1, ie, they
have a length word and are potentially TOASTable; while the term variable
width covers both varlena and cstring (and, perhaps, someday other types
with other rules for computing the actual width). No code changes in this
commit except for renaming a couple macros.
bitmap, if present).
Per Tom Lane's suggestion the information whether a tuple has an oid
or not is carried in the tuple descriptor. For debugging reasons
tdhasoid is of type char, not bool. There are predefined values for
WITHOID, WITHOUTOID and UNDEFOID.
This patch has been generated against a cvs snapshot from last week
and I don't expect it to apply cleanly to current sources. While I
post it here for public review, I'm working on a new version against a
current snapshot. (There's been heavy activity recently; hope to
catch up some day ...)
This is a long patch; if it is too hard to swallow, I can provide it
in smaller pieces:
Part 1: Accessor macros
Part 2: tdhasoid in TupDesc
Part 3: Regression test
Part 4: Parameter withoid to heap_addheader
Part 5: Eliminate t_oid from HeapTupleHeader
Part 2 is the most hairy part because of changes in the executor and
even in the parser; the other parts are straightforward.
Up to part 4 the patched postmaster stays binary compatible to
databases created with an unpatched version. Part 5 is small (100
lines) and finally breaks compatibility.
Manfred Koizar
patch from 2002-06-10, is supposed to reduce the heap tuple header size
by four bytes on most architectures. Of course it changes the on-disk
tuple format and therefore requires initdb.
This overlays cmin/cmax/xmax fields into only two fields.
Manfred Koizar
HeapTupleHeaderData in setter and getter macros called
HeapTupleHeaderGetXmin, HeapTupleHeaderSetXmin etc.
It also introduces a "virtual" field xvac by defining
HeapTupleHeaderGetXvac and HeapTupleHeaderSetXvac. Xvac is used by
VACUUM, in fact it is stored in t_cmin.
Manfred Koizar
where the latter is made slightly larger to allow for in-memory tuples
containing resjunk attributes. Responds to today's complaint that one
cannot UPDATE a table containing the allegedly-legal maximum number of
columns.
Also, apply Manfred Koizar's recent patch to avoid extra alignment padding
when there is a null bitmap. This saves bytes in some cases while not
creating any backward-compatibility problem AFAICS.
1. Distinguish cases where a Datum representing a tuple datatype is an OID
from cases where it is a pointer to TupleTableSlot, and make sure we use
the right typlen in each case.
2. Make fetchatt() and related code support 8-byte by-value datatypes on
machines where Datum is 8 bytes. Centralize knowledge of the available
by-value datatype sizes in two macros in tupmacs.h, so that this will be
easier if we ever have to do it again.
