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5db6df0c01
This adds new, required, table AM callbacks for insert/delete/update
and lock_tuple. To be able to reasonably use those, the EvalPlanQual
mechanism had to be adapted, moving more logic into the AM.
Previously both delete/update/lock call-sites and the EPQ mechanism had
to have awareness of the specific tuple format to be able to fetch the
latest version of a tuple. Obviously that needs to be abstracted
away. To do so, move the logic that find the latest row version into
the AM. lock_tuple has a new flag argument,
TUPLE_LOCK_FLAG_FIND_LAST_VERSION, that forces it to lock the last
version, rather than the current one. It'd have been possible to do
so via a separate callback as well, but finding the last version
usually also necessitates locking the newest version, making it
sensible to combine the two. This replaces the previous use of
EvalPlanQualFetch(). Additionally HeapTupleUpdated, which previously
signaled either a concurrent update or delete, is now split into two,
to avoid callers needing AM specific knowledge to differentiate.
The move of finding the latest row version into tuple_lock means that
encountering a row concurrently moved into another partition will now
raise an error about "tuple to be locked" rather than "tuple to be
updated/deleted" - which is accurate, as that always happens when
locking rows. While possible slightly less helpful for users, it seems
like an acceptable trade-off.
As part of this commit HTSU_Result has been renamed to TM_Result, and
its members been expanded to differentiated between updating and
deleting. HeapUpdateFailureData has been renamed to TM_FailureData.
The interface to speculative insertion is changed so nodeModifyTable.c
does not have to set the speculative token itself anymore. Instead
there's a version of tuple_insert, tuple_insert_speculative, that
performs the speculative insertion (without requiring a flag to signal
that fact), and the speculative insertion is either made permanent
with table_complete_speculative(succeeded = true) or aborted with
succeeded = false).
Note that multi_insert is not yet routed through tableam, nor is
COPY. Changing multi_insert requires changes to copy.c that are large
enough to better be done separately.
Similarly, although simpler, CREATE TABLE AS and CREATE MATERIALIZED
VIEW are also only going to be adjusted in a later commit.
Author: Andres Freund and Haribabu Kommi
Discussion:
https://postgr.es/m/20180703070645.wchpu5muyto5n647@alap3.anarazel.de
https://postgr.es/m/20190313003903.nwvrxi7rw3ywhdel@alap3.anarazel.de
https://postgr.es/m/20160812231527.GA690404@alvherre.pgsql
1719 lines
50 KiB
C
1719 lines
50 KiB
C
/*-------------------------------------------------------------------------
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*
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* heapam_visibility.c
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* Tuple visibility rules for tuples stored in heap.
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*
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* NOTE: all the HeapTupleSatisfies routines will update the tuple's
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* "hint" status bits if we see that the inserting or deleting transaction
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* has now committed or aborted (and it is safe to set the hint bits).
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* If the hint bits are changed, MarkBufferDirtyHint is called on
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* the passed-in buffer. The caller must hold not only a pin, but at least
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* shared buffer content lock on the buffer containing the tuple.
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*
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* NOTE: When using a non-MVCC snapshot, we must check
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* TransactionIdIsInProgress (which looks in the PGXACT array)
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* before TransactionIdDidCommit/TransactionIdDidAbort (which look in
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* pg_xact). Otherwise we have a race condition: we might decide that a
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* just-committed transaction crashed, because none of the tests succeed.
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* xact.c is careful to record commit/abort in pg_xact before it unsets
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* MyPgXact->xid in the PGXACT array. That fixes that problem, but it
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* also means there is a window where TransactionIdIsInProgress and
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* TransactionIdDidCommit will both return true. If we check only
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* TransactionIdDidCommit, we could consider a tuple committed when a
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* later GetSnapshotData call will still think the originating transaction
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* is in progress, which leads to application-level inconsistency. The
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* upshot is that we gotta check TransactionIdIsInProgress first in all
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* code paths, except for a few cases where we are looking at
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* subtransactions of our own main transaction and so there can't be any
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* race condition.
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*
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* When using an MVCC snapshot, we rely on XidInMVCCSnapshot rather than
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* TransactionIdIsInProgress, but the logic is otherwise the same: do not
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* check pg_xact until after deciding that the xact is no longer in progress.
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*
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*
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* Summary of visibility functions:
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*
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* HeapTupleSatisfiesMVCC()
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* visible to supplied snapshot, excludes current command
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* HeapTupleSatisfiesUpdate()
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* visible to instant snapshot, with user-supplied command
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* counter and more complex result
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* HeapTupleSatisfiesSelf()
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* visible to instant snapshot and current command
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* HeapTupleSatisfiesDirty()
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* like HeapTupleSatisfiesSelf(), but includes open transactions
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* HeapTupleSatisfiesVacuum()
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* visible to any running transaction, used by VACUUM
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* HeapTupleSatisfiesNonVacuumable()
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* Snapshot-style API for HeapTupleSatisfiesVacuum
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* HeapTupleSatisfiesToast()
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* visible unless part of interrupted vacuum, used for TOAST
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* HeapTupleSatisfiesAny()
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* all tuples are visible
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*
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* Portions Copyright (c) 1996-2019, PostgreSQL Global Development Group
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* Portions Copyright (c) 1994, Regents of the University of California
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*
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* IDENTIFICATION
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* src/backend/access/heap/heapam_visibility.c
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*
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*-------------------------------------------------------------------------
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*/
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#include "postgres.h"
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#include "access/heapam.h"
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#include "access/htup_details.h"
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#include "access/multixact.h"
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#include "access/subtrans.h"
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#include "access/tableam.h"
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#include "access/transam.h"
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#include "access/xact.h"
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#include "access/xlog.h"
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#include "storage/bufmgr.h"
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#include "storage/procarray.h"
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#include "utils/builtins.h"
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#include "utils/combocid.h"
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#include "utils/snapmgr.h"
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/*
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* SetHintBits()
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*
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* Set commit/abort hint bits on a tuple, if appropriate at this time.
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*
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* It is only safe to set a transaction-committed hint bit if we know the
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* transaction's commit record is guaranteed to be flushed to disk before the
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* buffer, or if the table is temporary or unlogged and will be obliterated by
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* a crash anyway. We cannot change the LSN of the page here, because we may
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* hold only a share lock on the buffer, so we can only use the LSN to
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* interlock this if the buffer's LSN already is newer than the commit LSN;
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* otherwise we have to just refrain from setting the hint bit until some
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* future re-examination of the tuple.
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*
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* We can always set hint bits when marking a transaction aborted. (Some
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* code in heapam.c relies on that!)
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*
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* Also, if we are cleaning up HEAP_MOVED_IN or HEAP_MOVED_OFF entries, then
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* we can always set the hint bits, since pre-9.0 VACUUM FULL always used
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* synchronous commits and didn't move tuples that weren't previously
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* hinted. (This is not known by this subroutine, but is applied by its
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* callers.) Note: old-style VACUUM FULL is gone, but we have to keep this
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* module's support for MOVED_OFF/MOVED_IN flag bits for as long as we
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* support in-place update from pre-9.0 databases.
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*
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* Normal commits may be asynchronous, so for those we need to get the LSN
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* of the transaction and then check whether this is flushed.
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*
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* The caller should pass xid as the XID of the transaction to check, or
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* InvalidTransactionId if no check is needed.
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*/
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static inline void
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SetHintBits(HeapTupleHeader tuple, Buffer buffer,
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uint16 infomask, TransactionId xid)
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{
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if (TransactionIdIsValid(xid))
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{
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/* NB: xid must be known committed here! */
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XLogRecPtr commitLSN = TransactionIdGetCommitLSN(xid);
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if (BufferIsPermanent(buffer) && XLogNeedsFlush(commitLSN) &&
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BufferGetLSNAtomic(buffer) < commitLSN)
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{
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/* not flushed and no LSN interlock, so don't set hint */
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return;
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}
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}
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tuple->t_infomask |= infomask;
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MarkBufferDirtyHint(buffer, true);
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}
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/*
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* HeapTupleSetHintBits --- exported version of SetHintBits()
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*
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* This must be separate because of C99's brain-dead notions about how to
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* implement inline functions.
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*/
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void
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HeapTupleSetHintBits(HeapTupleHeader tuple, Buffer buffer,
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uint16 infomask, TransactionId xid)
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{
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SetHintBits(tuple, buffer, infomask, xid);
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}
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/*
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* HeapTupleSatisfiesSelf
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* True iff heap tuple is valid "for itself".
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*
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* See SNAPSHOT_MVCC's definition for the intended behaviour.
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*
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* Note:
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* Assumes heap tuple is valid.
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*
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* The satisfaction of "itself" requires the following:
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*
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* ((Xmin == my-transaction && the row was updated by the current transaction, and
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* (Xmax is null it was not deleted
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* [|| Xmax != my-transaction)]) [or it was deleted by another transaction]
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* ||
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*
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* (Xmin is committed && the row was modified by a committed transaction, and
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* (Xmax is null || the row has not been deleted, or
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* (Xmax != my-transaction && the row was deleted by another transaction
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* Xmax is not committed))) that has not been committed
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*/
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static bool
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HeapTupleSatisfiesSelf(HeapTuple htup, Snapshot snapshot, Buffer buffer)
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{
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HeapTupleHeader tuple = htup->t_data;
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Assert(ItemPointerIsValid(&htup->t_self));
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Assert(htup->t_tableOid != InvalidOid);
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if (!HeapTupleHeaderXminCommitted(tuple))
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{
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if (HeapTupleHeaderXminInvalid(tuple))
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return false;
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/* Used by pre-9.0 binary upgrades */
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if (tuple->t_infomask & HEAP_MOVED_OFF)
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{
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TransactionId xvac = HeapTupleHeaderGetXvac(tuple);
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if (TransactionIdIsCurrentTransactionId(xvac))
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return false;
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if (!TransactionIdIsInProgress(xvac))
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{
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if (TransactionIdDidCommit(xvac))
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{
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SetHintBits(tuple, buffer, HEAP_XMIN_INVALID,
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InvalidTransactionId);
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return false;
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}
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SetHintBits(tuple, buffer, HEAP_XMIN_COMMITTED,
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InvalidTransactionId);
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}
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}
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/* Used by pre-9.0 binary upgrades */
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else if (tuple->t_infomask & HEAP_MOVED_IN)
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{
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TransactionId xvac = HeapTupleHeaderGetXvac(tuple);
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if (!TransactionIdIsCurrentTransactionId(xvac))
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{
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if (TransactionIdIsInProgress(xvac))
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return false;
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if (TransactionIdDidCommit(xvac))
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SetHintBits(tuple, buffer, HEAP_XMIN_COMMITTED,
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InvalidTransactionId);
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else
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{
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SetHintBits(tuple, buffer, HEAP_XMIN_INVALID,
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InvalidTransactionId);
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return false;
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}
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}
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}
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else if (TransactionIdIsCurrentTransactionId(HeapTupleHeaderGetRawXmin(tuple)))
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{
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if (tuple->t_infomask & HEAP_XMAX_INVALID) /* xid invalid */
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return true;
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if (HEAP_XMAX_IS_LOCKED_ONLY(tuple->t_infomask)) /* not deleter */
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return true;
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if (tuple->t_infomask & HEAP_XMAX_IS_MULTI)
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{
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TransactionId xmax;
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xmax = HeapTupleGetUpdateXid(tuple);
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/* not LOCKED_ONLY, so it has to have an xmax */
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Assert(TransactionIdIsValid(xmax));
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/* updating subtransaction must have aborted */
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if (!TransactionIdIsCurrentTransactionId(xmax))
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return true;
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else
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return false;
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}
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if (!TransactionIdIsCurrentTransactionId(HeapTupleHeaderGetRawXmax(tuple)))
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{
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/* deleting subtransaction must have aborted */
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SetHintBits(tuple, buffer, HEAP_XMAX_INVALID,
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InvalidTransactionId);
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return true;
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}
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return false;
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}
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else if (TransactionIdIsInProgress(HeapTupleHeaderGetRawXmin(tuple)))
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return false;
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else if (TransactionIdDidCommit(HeapTupleHeaderGetRawXmin(tuple)))
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SetHintBits(tuple, buffer, HEAP_XMIN_COMMITTED,
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HeapTupleHeaderGetRawXmin(tuple));
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else
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{
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/* it must have aborted or crashed */
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SetHintBits(tuple, buffer, HEAP_XMIN_INVALID,
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InvalidTransactionId);
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return false;
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}
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}
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/* by here, the inserting transaction has committed */
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if (tuple->t_infomask & HEAP_XMAX_INVALID) /* xid invalid or aborted */
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return true;
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if (tuple->t_infomask & HEAP_XMAX_COMMITTED)
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{
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if (HEAP_XMAX_IS_LOCKED_ONLY(tuple->t_infomask))
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return true;
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return false; /* updated by other */
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}
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if (tuple->t_infomask & HEAP_XMAX_IS_MULTI)
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{
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TransactionId xmax;
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if (HEAP_XMAX_IS_LOCKED_ONLY(tuple->t_infomask))
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return true;
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xmax = HeapTupleGetUpdateXid(tuple);
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/* not LOCKED_ONLY, so it has to have an xmax */
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Assert(TransactionIdIsValid(xmax));
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if (TransactionIdIsCurrentTransactionId(xmax))
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return false;
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if (TransactionIdIsInProgress(xmax))
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return true;
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if (TransactionIdDidCommit(xmax))
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return false;
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/* it must have aborted or crashed */
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return true;
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}
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if (TransactionIdIsCurrentTransactionId(HeapTupleHeaderGetRawXmax(tuple)))
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{
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if (HEAP_XMAX_IS_LOCKED_ONLY(tuple->t_infomask))
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return true;
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return false;
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}
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if (TransactionIdIsInProgress(HeapTupleHeaderGetRawXmax(tuple)))
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return true;
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if (!TransactionIdDidCommit(HeapTupleHeaderGetRawXmax(tuple)))
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{
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/* it must have aborted or crashed */
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SetHintBits(tuple, buffer, HEAP_XMAX_INVALID,
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InvalidTransactionId);
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return true;
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}
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/* xmax transaction committed */
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if (HEAP_XMAX_IS_LOCKED_ONLY(tuple->t_infomask))
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{
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SetHintBits(tuple, buffer, HEAP_XMAX_INVALID,
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InvalidTransactionId);
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return true;
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}
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SetHintBits(tuple, buffer, HEAP_XMAX_COMMITTED,
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HeapTupleHeaderGetRawXmax(tuple));
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return false;
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}
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/*
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* HeapTupleSatisfiesAny
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* Dummy "satisfies" routine: any tuple satisfies SnapshotAny.
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*/
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static bool
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HeapTupleSatisfiesAny(HeapTuple htup, Snapshot snapshot, Buffer buffer)
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{
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return true;
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}
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/*
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* HeapTupleSatisfiesToast
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* True iff heap tuple is valid as a TOAST row.
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*
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* See SNAPSHOT_TOAST's definition for the intended behaviour.
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*
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* This is a simplified version that only checks for VACUUM moving conditions.
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* It's appropriate for TOAST usage because TOAST really doesn't want to do
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* its own time qual checks; if you can see the main table row that contains
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* a TOAST reference, you should be able to see the TOASTed value. However,
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* vacuuming a TOAST table is independent of the main table, and in case such
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* a vacuum fails partway through, we'd better do this much checking.
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*
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* Among other things, this means you can't do UPDATEs of rows in a TOAST
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* table.
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*/
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static bool
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HeapTupleSatisfiesToast(HeapTuple htup, Snapshot snapshot,
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Buffer buffer)
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{
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HeapTupleHeader tuple = htup->t_data;
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Assert(ItemPointerIsValid(&htup->t_self));
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Assert(htup->t_tableOid != InvalidOid);
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if (!HeapTupleHeaderXminCommitted(tuple))
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{
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if (HeapTupleHeaderXminInvalid(tuple))
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return false;
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|
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/* Used by pre-9.0 binary upgrades */
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if (tuple->t_infomask & HEAP_MOVED_OFF)
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{
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TransactionId xvac = HeapTupleHeaderGetXvac(tuple);
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if (TransactionIdIsCurrentTransactionId(xvac))
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return false;
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if (!TransactionIdIsInProgress(xvac))
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{
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if (TransactionIdDidCommit(xvac))
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{
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SetHintBits(tuple, buffer, HEAP_XMIN_INVALID,
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InvalidTransactionId);
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return false;
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}
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SetHintBits(tuple, buffer, HEAP_XMIN_COMMITTED,
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InvalidTransactionId);
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}
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}
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/* Used by pre-9.0 binary upgrades */
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else if (tuple->t_infomask & HEAP_MOVED_IN)
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{
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TransactionId xvac = HeapTupleHeaderGetXvac(tuple);
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|
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if (!TransactionIdIsCurrentTransactionId(xvac))
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{
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if (TransactionIdIsInProgress(xvac))
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return false;
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if (TransactionIdDidCommit(xvac))
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SetHintBits(tuple, buffer, HEAP_XMIN_COMMITTED,
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InvalidTransactionId);
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else
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{
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SetHintBits(tuple, buffer, HEAP_XMIN_INVALID,
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InvalidTransactionId);
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return false;
|
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}
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}
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}
|
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|
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/*
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* An invalid Xmin can be left behind by a speculative insertion that
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* is canceled by super-deleting the tuple. This also applies to
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* TOAST tuples created during speculative insertion.
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*/
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else if (!TransactionIdIsValid(HeapTupleHeaderGetXmin(tuple)))
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return false;
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}
|
|
|
|
/* otherwise assume the tuple is valid for TOAST. */
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return true;
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}
|
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|
|
/*
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|
* HeapTupleSatisfiesUpdate
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*
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* This function returns a more detailed result code than most of the
|
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* functions in this file, since UPDATE needs to know more than "is it
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* visible?". It also allows for user-supplied CommandId rather than
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* relying on CurrentCommandId.
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*
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|
* The possible return codes are:
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*
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* TM_Invisible: the tuple didn't exist at all when the scan started, e.g. it
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* was created by a later CommandId.
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*
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* TM_Ok: The tuple is valid and visible, so it may be updated.
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*
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* TM_SelfModified: The tuple was updated by the current transaction, after
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* the current scan started.
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*
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|
* TM_Updated: The tuple was updated by a committed transaction (including
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* the case where the tuple was moved into a different partition).
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*
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* TM_Deleted: The tuple was deleted by a committed transaction.
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*
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* TM_BeingModified: The tuple is being updated by an in-progress transaction
|
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* other than the current transaction. (Note: this includes the case where
|
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* the tuple is share-locked by a MultiXact, even if the MultiXact includes
|
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* the current transaction. Callers that want to distinguish that case must
|
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* test for it themselves.)
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|
*/
|
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TM_Result
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HeapTupleSatisfiesUpdate(HeapTuple htup, CommandId curcid,
|
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Buffer buffer)
|
|
{
|
|
HeapTupleHeader tuple = htup->t_data;
|
|
|
|
Assert(ItemPointerIsValid(&htup->t_self));
|
|
Assert(htup->t_tableOid != InvalidOid);
|
|
|
|
if (!HeapTupleHeaderXminCommitted(tuple))
|
|
{
|
|
if (HeapTupleHeaderXminInvalid(tuple))
|
|
return TM_Invisible;
|
|
|
|
/* Used by pre-9.0 binary upgrades */
|
|
if (tuple->t_infomask & HEAP_MOVED_OFF)
|
|
{
|
|
TransactionId xvac = HeapTupleHeaderGetXvac(tuple);
|
|
|
|
if (TransactionIdIsCurrentTransactionId(xvac))
|
|
return TM_Invisible;
|
|
if (!TransactionIdIsInProgress(xvac))
|
|
{
|
|
if (TransactionIdDidCommit(xvac))
|
|
{
|
|
SetHintBits(tuple, buffer, HEAP_XMIN_INVALID,
|
|
InvalidTransactionId);
|
|
return TM_Invisible;
|
|
}
|
|
SetHintBits(tuple, buffer, HEAP_XMIN_COMMITTED,
|
|
InvalidTransactionId);
|
|
}
|
|
}
|
|
/* Used by pre-9.0 binary upgrades */
|
|
else if (tuple->t_infomask & HEAP_MOVED_IN)
|
|
{
|
|
TransactionId xvac = HeapTupleHeaderGetXvac(tuple);
|
|
|
|
if (!TransactionIdIsCurrentTransactionId(xvac))
|
|
{
|
|
if (TransactionIdIsInProgress(xvac))
|
|
return TM_Invisible;
|
|
if (TransactionIdDidCommit(xvac))
|
|
SetHintBits(tuple, buffer, HEAP_XMIN_COMMITTED,
|
|
InvalidTransactionId);
|
|
else
|
|
{
|
|
SetHintBits(tuple, buffer, HEAP_XMIN_INVALID,
|
|
InvalidTransactionId);
|
|
return TM_Invisible;
|
|
}
|
|
}
|
|
}
|
|
else if (TransactionIdIsCurrentTransactionId(HeapTupleHeaderGetRawXmin(tuple)))
|
|
{
|
|
if (HeapTupleHeaderGetCmin(tuple) >= curcid)
|
|
return TM_Invisible; /* inserted after scan started */
|
|
|
|
if (tuple->t_infomask & HEAP_XMAX_INVALID) /* xid invalid */
|
|
return TM_Ok;
|
|
|
|
if (HEAP_XMAX_IS_LOCKED_ONLY(tuple->t_infomask))
|
|
{
|
|
TransactionId xmax;
|
|
|
|
xmax = HeapTupleHeaderGetRawXmax(tuple);
|
|
|
|
/*
|
|
* Careful here: even though this tuple was created by our own
|
|
* transaction, it might be locked by other transactions, if
|
|
* the original version was key-share locked when we updated
|
|
* it.
|
|
*/
|
|
|
|
if (tuple->t_infomask & HEAP_XMAX_IS_MULTI)
|
|
{
|
|
if (MultiXactIdIsRunning(xmax, true))
|
|
return TM_BeingModified;
|
|
else
|
|
return TM_Ok;
|
|
}
|
|
|
|
/*
|
|
* If the locker is gone, then there is nothing of interest
|
|
* left in this Xmax; otherwise, report the tuple as
|
|
* locked/updated.
|
|
*/
|
|
if (!TransactionIdIsInProgress(xmax))
|
|
return TM_Ok;
|
|
return TM_BeingModified;
|
|
}
|
|
|
|
if (tuple->t_infomask & HEAP_XMAX_IS_MULTI)
|
|
{
|
|
TransactionId xmax;
|
|
|
|
xmax = HeapTupleGetUpdateXid(tuple);
|
|
|
|
/* not LOCKED_ONLY, so it has to have an xmax */
|
|
Assert(TransactionIdIsValid(xmax));
|
|
|
|
/* deleting subtransaction must have aborted */
|
|
if (!TransactionIdIsCurrentTransactionId(xmax))
|
|
{
|
|
if (MultiXactIdIsRunning(HeapTupleHeaderGetRawXmax(tuple),
|
|
false))
|
|
return TM_BeingModified;
|
|
return TM_Ok;
|
|
}
|
|
else
|
|
{
|
|
if (HeapTupleHeaderGetCmax(tuple) >= curcid)
|
|
return TM_SelfModified; /* updated after scan started */
|
|
else
|
|
return TM_Invisible; /* updated before scan started */
|
|
}
|
|
}
|
|
|
|
if (!TransactionIdIsCurrentTransactionId(HeapTupleHeaderGetRawXmax(tuple)))
|
|
{
|
|
/* deleting subtransaction must have aborted */
|
|
SetHintBits(tuple, buffer, HEAP_XMAX_INVALID,
|
|
InvalidTransactionId);
|
|
return TM_Ok;
|
|
}
|
|
|
|
if (HeapTupleHeaderGetCmax(tuple) >= curcid)
|
|
return TM_SelfModified; /* updated after scan started */
|
|
else
|
|
return TM_Invisible; /* updated before scan started */
|
|
}
|
|
else if (TransactionIdIsInProgress(HeapTupleHeaderGetRawXmin(tuple)))
|
|
return TM_Invisible;
|
|
else if (TransactionIdDidCommit(HeapTupleHeaderGetRawXmin(tuple)))
|
|
SetHintBits(tuple, buffer, HEAP_XMIN_COMMITTED,
|
|
HeapTupleHeaderGetRawXmin(tuple));
|
|
else
|
|
{
|
|
/* it must have aborted or crashed */
|
|
SetHintBits(tuple, buffer, HEAP_XMIN_INVALID,
|
|
InvalidTransactionId);
|
|
return TM_Invisible;
|
|
}
|
|
}
|
|
|
|
/* by here, the inserting transaction has committed */
|
|
|
|
if (tuple->t_infomask & HEAP_XMAX_INVALID) /* xid invalid or aborted */
|
|
return TM_Ok;
|
|
|
|
if (tuple->t_infomask & HEAP_XMAX_COMMITTED)
|
|
{
|
|
if (HEAP_XMAX_IS_LOCKED_ONLY(tuple->t_infomask))
|
|
return TM_Ok;
|
|
if (!ItemPointerEquals(&htup->t_self, &tuple->t_ctid) ||
|
|
HeapTupleHeaderIndicatesMovedPartitions(tuple))
|
|
return TM_Updated; /* updated by other */
|
|
else
|
|
return TM_Deleted; /* deleted by other */
|
|
}
|
|
|
|
if (tuple->t_infomask & HEAP_XMAX_IS_MULTI)
|
|
{
|
|
TransactionId xmax;
|
|
|
|
if (HEAP_LOCKED_UPGRADED(tuple->t_infomask))
|
|
return TM_Ok;
|
|
|
|
if (HEAP_XMAX_IS_LOCKED_ONLY(tuple->t_infomask))
|
|
{
|
|
if (MultiXactIdIsRunning(HeapTupleHeaderGetRawXmax(tuple), true))
|
|
return TM_BeingModified;
|
|
|
|
SetHintBits(tuple, buffer, HEAP_XMAX_INVALID, InvalidTransactionId);
|
|
return TM_Ok;
|
|
}
|
|
|
|
xmax = HeapTupleGetUpdateXid(tuple);
|
|
if (!TransactionIdIsValid(xmax))
|
|
{
|
|
if (MultiXactIdIsRunning(HeapTupleHeaderGetRawXmax(tuple), false))
|
|
return TM_BeingModified;
|
|
}
|
|
|
|
/* not LOCKED_ONLY, so it has to have an xmax */
|
|
Assert(TransactionIdIsValid(xmax));
|
|
|
|
if (TransactionIdIsCurrentTransactionId(xmax))
|
|
{
|
|
if (HeapTupleHeaderGetCmax(tuple) >= curcid)
|
|
return TM_SelfModified; /* updated after scan started */
|
|
else
|
|
return TM_Invisible; /* updated before scan started */
|
|
}
|
|
|
|
if (MultiXactIdIsRunning(HeapTupleHeaderGetRawXmax(tuple), false))
|
|
return TM_BeingModified;
|
|
|
|
if (TransactionIdDidCommit(xmax))
|
|
{
|
|
if (!ItemPointerEquals(&htup->t_self, &tuple->t_ctid) ||
|
|
HeapTupleHeaderIndicatesMovedPartitions(tuple))
|
|
return TM_Updated;
|
|
else
|
|
return TM_Deleted;
|
|
}
|
|
|
|
/*
|
|
* By here, the update in the Xmax is either aborted or crashed, but
|
|
* what about the other members?
|
|
*/
|
|
|
|
if (!MultiXactIdIsRunning(HeapTupleHeaderGetRawXmax(tuple), false))
|
|
{
|
|
/*
|
|
* There's no member, even just a locker, alive anymore, so we can
|
|
* mark the Xmax as invalid.
|
|
*/
|
|
SetHintBits(tuple, buffer, HEAP_XMAX_INVALID,
|
|
InvalidTransactionId);
|
|
return TM_Ok;
|
|
}
|
|
else
|
|
{
|
|
/* There are lockers running */
|
|
return TM_BeingModified;
|
|
}
|
|
}
|
|
|
|
if (TransactionIdIsCurrentTransactionId(HeapTupleHeaderGetRawXmax(tuple)))
|
|
{
|
|
if (HEAP_XMAX_IS_LOCKED_ONLY(tuple->t_infomask))
|
|
return TM_BeingModified;
|
|
if (HeapTupleHeaderGetCmax(tuple) >= curcid)
|
|
return TM_SelfModified; /* updated after scan started */
|
|
else
|
|
return TM_Invisible; /* updated before scan started */
|
|
}
|
|
|
|
if (TransactionIdIsInProgress(HeapTupleHeaderGetRawXmax(tuple)))
|
|
return TM_BeingModified;
|
|
|
|
if (!TransactionIdDidCommit(HeapTupleHeaderGetRawXmax(tuple)))
|
|
{
|
|
/* it must have aborted or crashed */
|
|
SetHintBits(tuple, buffer, HEAP_XMAX_INVALID,
|
|
InvalidTransactionId);
|
|
return TM_Ok;
|
|
}
|
|
|
|
/* xmax transaction committed */
|
|
|
|
if (HEAP_XMAX_IS_LOCKED_ONLY(tuple->t_infomask))
|
|
{
|
|
SetHintBits(tuple, buffer, HEAP_XMAX_INVALID,
|
|
InvalidTransactionId);
|
|
return TM_Ok;
|
|
}
|
|
|
|
SetHintBits(tuple, buffer, HEAP_XMAX_COMMITTED,
|
|
HeapTupleHeaderGetRawXmax(tuple));
|
|
if (!ItemPointerEquals(&htup->t_self, &tuple->t_ctid) ||
|
|
HeapTupleHeaderIndicatesMovedPartitions(tuple))
|
|
return TM_Updated; /* updated by other */
|
|
else
|
|
return TM_Deleted; /* deleted by other */
|
|
}
|
|
|
|
/*
|
|
* HeapTupleSatisfiesDirty
|
|
* True iff heap tuple is valid including effects of open transactions.
|
|
*
|
|
* See SNAPSHOT_DIRTY's definition for the intended behaviour.
|
|
*
|
|
* This is essentially like HeapTupleSatisfiesSelf as far as effects of
|
|
* the current transaction and committed/aborted xacts are concerned.
|
|
* However, we also include the effects of other xacts still in progress.
|
|
*
|
|
* A special hack is that the passed-in snapshot struct is used as an
|
|
* output argument to return the xids of concurrent xacts that affected the
|
|
* tuple. snapshot->xmin is set to the tuple's xmin if that is another
|
|
* transaction that's still in progress; or to InvalidTransactionId if the
|
|
* tuple's xmin is committed good, committed dead, or my own xact.
|
|
* Similarly for snapshot->xmax and the tuple's xmax. If the tuple was
|
|
* inserted speculatively, meaning that the inserter might still back down
|
|
* on the insertion without aborting the whole transaction, the associated
|
|
* token is also returned in snapshot->speculativeToken.
|
|
*/
|
|
static bool
|
|
HeapTupleSatisfiesDirty(HeapTuple htup, Snapshot snapshot,
|
|
Buffer buffer)
|
|
{
|
|
HeapTupleHeader tuple = htup->t_data;
|
|
|
|
Assert(ItemPointerIsValid(&htup->t_self));
|
|
Assert(htup->t_tableOid != InvalidOid);
|
|
|
|
snapshot->xmin = snapshot->xmax = InvalidTransactionId;
|
|
snapshot->speculativeToken = 0;
|
|
|
|
if (!HeapTupleHeaderXminCommitted(tuple))
|
|
{
|
|
if (HeapTupleHeaderXminInvalid(tuple))
|
|
return false;
|
|
|
|
/* Used by pre-9.0 binary upgrades */
|
|
if (tuple->t_infomask & HEAP_MOVED_OFF)
|
|
{
|
|
TransactionId xvac = HeapTupleHeaderGetXvac(tuple);
|
|
|
|
if (TransactionIdIsCurrentTransactionId(xvac))
|
|
return false;
|
|
if (!TransactionIdIsInProgress(xvac))
|
|
{
|
|
if (TransactionIdDidCommit(xvac))
|
|
{
|
|
SetHintBits(tuple, buffer, HEAP_XMIN_INVALID,
|
|
InvalidTransactionId);
|
|
return false;
|
|
}
|
|
SetHintBits(tuple, buffer, HEAP_XMIN_COMMITTED,
|
|
InvalidTransactionId);
|
|
}
|
|
}
|
|
/* Used by pre-9.0 binary upgrades */
|
|
else if (tuple->t_infomask & HEAP_MOVED_IN)
|
|
{
|
|
TransactionId xvac = HeapTupleHeaderGetXvac(tuple);
|
|
|
|
if (!TransactionIdIsCurrentTransactionId(xvac))
|
|
{
|
|
if (TransactionIdIsInProgress(xvac))
|
|
return false;
|
|
if (TransactionIdDidCommit(xvac))
|
|
SetHintBits(tuple, buffer, HEAP_XMIN_COMMITTED,
|
|
InvalidTransactionId);
|
|
else
|
|
{
|
|
SetHintBits(tuple, buffer, HEAP_XMIN_INVALID,
|
|
InvalidTransactionId);
|
|
return false;
|
|
}
|
|
}
|
|
}
|
|
else if (TransactionIdIsCurrentTransactionId(HeapTupleHeaderGetRawXmin(tuple)))
|
|
{
|
|
if (tuple->t_infomask & HEAP_XMAX_INVALID) /* xid invalid */
|
|
return true;
|
|
|
|
if (HEAP_XMAX_IS_LOCKED_ONLY(tuple->t_infomask)) /* not deleter */
|
|
return true;
|
|
|
|
if (tuple->t_infomask & HEAP_XMAX_IS_MULTI)
|
|
{
|
|
TransactionId xmax;
|
|
|
|
xmax = HeapTupleGetUpdateXid(tuple);
|
|
|
|
/* not LOCKED_ONLY, so it has to have an xmax */
|
|
Assert(TransactionIdIsValid(xmax));
|
|
|
|
/* updating subtransaction must have aborted */
|
|
if (!TransactionIdIsCurrentTransactionId(xmax))
|
|
return true;
|
|
else
|
|
return false;
|
|
}
|
|
|
|
if (!TransactionIdIsCurrentTransactionId(HeapTupleHeaderGetRawXmax(tuple)))
|
|
{
|
|
/* deleting subtransaction must have aborted */
|
|
SetHintBits(tuple, buffer, HEAP_XMAX_INVALID,
|
|
InvalidTransactionId);
|
|
return true;
|
|
}
|
|
|
|
return false;
|
|
}
|
|
else if (TransactionIdIsInProgress(HeapTupleHeaderGetRawXmin(tuple)))
|
|
{
|
|
/*
|
|
* Return the speculative token to caller. Caller can worry about
|
|
* xmax, since it requires a conclusively locked row version, and
|
|
* a concurrent update to this tuple is a conflict of its
|
|
* purposes.
|
|
*/
|
|
if (HeapTupleHeaderIsSpeculative(tuple))
|
|
{
|
|
snapshot->speculativeToken =
|
|
HeapTupleHeaderGetSpeculativeToken(tuple);
|
|
|
|
Assert(snapshot->speculativeToken != 0);
|
|
}
|
|
|
|
snapshot->xmin = HeapTupleHeaderGetRawXmin(tuple);
|
|
/* XXX shouldn't we fall through to look at xmax? */
|
|
return true; /* in insertion by other */
|
|
}
|
|
else if (TransactionIdDidCommit(HeapTupleHeaderGetRawXmin(tuple)))
|
|
SetHintBits(tuple, buffer, HEAP_XMIN_COMMITTED,
|
|
HeapTupleHeaderGetRawXmin(tuple));
|
|
else
|
|
{
|
|
/* it must have aborted or crashed */
|
|
SetHintBits(tuple, buffer, HEAP_XMIN_INVALID,
|
|
InvalidTransactionId);
|
|
return false;
|
|
}
|
|
}
|
|
|
|
/* by here, the inserting transaction has committed */
|
|
|
|
if (tuple->t_infomask & HEAP_XMAX_INVALID) /* xid invalid or aborted */
|
|
return true;
|
|
|
|
if (tuple->t_infomask & HEAP_XMAX_COMMITTED)
|
|
{
|
|
if (HEAP_XMAX_IS_LOCKED_ONLY(tuple->t_infomask))
|
|
return true;
|
|
return false; /* updated by other */
|
|
}
|
|
|
|
if (tuple->t_infomask & HEAP_XMAX_IS_MULTI)
|
|
{
|
|
TransactionId xmax;
|
|
|
|
if (HEAP_XMAX_IS_LOCKED_ONLY(tuple->t_infomask))
|
|
return true;
|
|
|
|
xmax = HeapTupleGetUpdateXid(tuple);
|
|
|
|
/* not LOCKED_ONLY, so it has to have an xmax */
|
|
Assert(TransactionIdIsValid(xmax));
|
|
|
|
if (TransactionIdIsCurrentTransactionId(xmax))
|
|
return false;
|
|
if (TransactionIdIsInProgress(xmax))
|
|
{
|
|
snapshot->xmax = xmax;
|
|
return true;
|
|
}
|
|
if (TransactionIdDidCommit(xmax))
|
|
return false;
|
|
/* it must have aborted or crashed */
|
|
return true;
|
|
}
|
|
|
|
if (TransactionIdIsCurrentTransactionId(HeapTupleHeaderGetRawXmax(tuple)))
|
|
{
|
|
if (HEAP_XMAX_IS_LOCKED_ONLY(tuple->t_infomask))
|
|
return true;
|
|
return false;
|
|
}
|
|
|
|
if (TransactionIdIsInProgress(HeapTupleHeaderGetRawXmax(tuple)))
|
|
{
|
|
if (!HEAP_XMAX_IS_LOCKED_ONLY(tuple->t_infomask))
|
|
snapshot->xmax = HeapTupleHeaderGetRawXmax(tuple);
|
|
return true;
|
|
}
|
|
|
|
if (!TransactionIdDidCommit(HeapTupleHeaderGetRawXmax(tuple)))
|
|
{
|
|
/* it must have aborted or crashed */
|
|
SetHintBits(tuple, buffer, HEAP_XMAX_INVALID,
|
|
InvalidTransactionId);
|
|
return true;
|
|
}
|
|
|
|
/* xmax transaction committed */
|
|
|
|
if (HEAP_XMAX_IS_LOCKED_ONLY(tuple->t_infomask))
|
|
{
|
|
SetHintBits(tuple, buffer, HEAP_XMAX_INVALID,
|
|
InvalidTransactionId);
|
|
return true;
|
|
}
|
|
|
|
SetHintBits(tuple, buffer, HEAP_XMAX_COMMITTED,
|
|
HeapTupleHeaderGetRawXmax(tuple));
|
|
return false; /* updated by other */
|
|
}
|
|
|
|
/*
|
|
* HeapTupleSatisfiesMVCC
|
|
* True iff heap tuple is valid for the given MVCC snapshot.
|
|
*
|
|
* See SNAPSHOT_MVCC's definition for the intended behaviour.
|
|
*
|
|
* Notice that here, we will not update the tuple status hint bits if the
|
|
* inserting/deleting transaction is still running according to our snapshot,
|
|
* even if in reality it's committed or aborted by now. This is intentional.
|
|
* Checking the true transaction state would require access to high-traffic
|
|
* shared data structures, creating contention we'd rather do without, and it
|
|
* would not change the result of our visibility check anyway. The hint bits
|
|
* will be updated by the first visitor that has a snapshot new enough to see
|
|
* the inserting/deleting transaction as done. In the meantime, the cost of
|
|
* leaving the hint bits unset is basically that each HeapTupleSatisfiesMVCC
|
|
* call will need to run TransactionIdIsCurrentTransactionId in addition to
|
|
* XidInMVCCSnapshot (but it would have to do the latter anyway). In the old
|
|
* coding where we tried to set the hint bits as soon as possible, we instead
|
|
* did TransactionIdIsInProgress in each call --- to no avail, as long as the
|
|
* inserting/deleting transaction was still running --- which was more cycles
|
|
* and more contention on the PGXACT array.
|
|
*/
|
|
static bool
|
|
HeapTupleSatisfiesMVCC(HeapTuple htup, Snapshot snapshot,
|
|
Buffer buffer)
|
|
{
|
|
HeapTupleHeader tuple = htup->t_data;
|
|
|
|
Assert(ItemPointerIsValid(&htup->t_self));
|
|
Assert(htup->t_tableOid != InvalidOid);
|
|
|
|
if (!HeapTupleHeaderXminCommitted(tuple))
|
|
{
|
|
if (HeapTupleHeaderXminInvalid(tuple))
|
|
return false;
|
|
|
|
/* Used by pre-9.0 binary upgrades */
|
|
if (tuple->t_infomask & HEAP_MOVED_OFF)
|
|
{
|
|
TransactionId xvac = HeapTupleHeaderGetXvac(tuple);
|
|
|
|
if (TransactionIdIsCurrentTransactionId(xvac))
|
|
return false;
|
|
if (!XidInMVCCSnapshot(xvac, snapshot))
|
|
{
|
|
if (TransactionIdDidCommit(xvac))
|
|
{
|
|
SetHintBits(tuple, buffer, HEAP_XMIN_INVALID,
|
|
InvalidTransactionId);
|
|
return false;
|
|
}
|
|
SetHintBits(tuple, buffer, HEAP_XMIN_COMMITTED,
|
|
InvalidTransactionId);
|
|
}
|
|
}
|
|
/* Used by pre-9.0 binary upgrades */
|
|
else if (tuple->t_infomask & HEAP_MOVED_IN)
|
|
{
|
|
TransactionId xvac = HeapTupleHeaderGetXvac(tuple);
|
|
|
|
if (!TransactionIdIsCurrentTransactionId(xvac))
|
|
{
|
|
if (XidInMVCCSnapshot(xvac, snapshot))
|
|
return false;
|
|
if (TransactionIdDidCommit(xvac))
|
|
SetHintBits(tuple, buffer, HEAP_XMIN_COMMITTED,
|
|
InvalidTransactionId);
|
|
else
|
|
{
|
|
SetHintBits(tuple, buffer, HEAP_XMIN_INVALID,
|
|
InvalidTransactionId);
|
|
return false;
|
|
}
|
|
}
|
|
}
|
|
else if (TransactionIdIsCurrentTransactionId(HeapTupleHeaderGetRawXmin(tuple)))
|
|
{
|
|
if (HeapTupleHeaderGetCmin(tuple) >= snapshot->curcid)
|
|
return false; /* inserted after scan started */
|
|
|
|
if (tuple->t_infomask & HEAP_XMAX_INVALID) /* xid invalid */
|
|
return true;
|
|
|
|
if (HEAP_XMAX_IS_LOCKED_ONLY(tuple->t_infomask)) /* not deleter */
|
|
return true;
|
|
|
|
if (tuple->t_infomask & HEAP_XMAX_IS_MULTI)
|
|
{
|
|
TransactionId xmax;
|
|
|
|
xmax = HeapTupleGetUpdateXid(tuple);
|
|
|
|
/* not LOCKED_ONLY, so it has to have an xmax */
|
|
Assert(TransactionIdIsValid(xmax));
|
|
|
|
/* updating subtransaction must have aborted */
|
|
if (!TransactionIdIsCurrentTransactionId(xmax))
|
|
return true;
|
|
else if (HeapTupleHeaderGetCmax(tuple) >= snapshot->curcid)
|
|
return true; /* updated after scan started */
|
|
else
|
|
return false; /* updated before scan started */
|
|
}
|
|
|
|
if (!TransactionIdIsCurrentTransactionId(HeapTupleHeaderGetRawXmax(tuple)))
|
|
{
|
|
/* deleting subtransaction must have aborted */
|
|
SetHintBits(tuple, buffer, HEAP_XMAX_INVALID,
|
|
InvalidTransactionId);
|
|
return true;
|
|
}
|
|
|
|
if (HeapTupleHeaderGetCmax(tuple) >= snapshot->curcid)
|
|
return true; /* deleted after scan started */
|
|
else
|
|
return false; /* deleted before scan started */
|
|
}
|
|
else if (XidInMVCCSnapshot(HeapTupleHeaderGetRawXmin(tuple), snapshot))
|
|
return false;
|
|
else if (TransactionIdDidCommit(HeapTupleHeaderGetRawXmin(tuple)))
|
|
SetHintBits(tuple, buffer, HEAP_XMIN_COMMITTED,
|
|
HeapTupleHeaderGetRawXmin(tuple));
|
|
else
|
|
{
|
|
/* it must have aborted or crashed */
|
|
SetHintBits(tuple, buffer, HEAP_XMIN_INVALID,
|
|
InvalidTransactionId);
|
|
return false;
|
|
}
|
|
}
|
|
else
|
|
{
|
|
/* xmin is committed, but maybe not according to our snapshot */
|
|
if (!HeapTupleHeaderXminFrozen(tuple) &&
|
|
XidInMVCCSnapshot(HeapTupleHeaderGetRawXmin(tuple), snapshot))
|
|
return false; /* treat as still in progress */
|
|
}
|
|
|
|
/* by here, the inserting transaction has committed */
|
|
|
|
if (tuple->t_infomask & HEAP_XMAX_INVALID) /* xid invalid or aborted */
|
|
return true;
|
|
|
|
if (HEAP_XMAX_IS_LOCKED_ONLY(tuple->t_infomask))
|
|
return true;
|
|
|
|
if (tuple->t_infomask & HEAP_XMAX_IS_MULTI)
|
|
{
|
|
TransactionId xmax;
|
|
|
|
/* already checked above */
|
|
Assert(!HEAP_XMAX_IS_LOCKED_ONLY(tuple->t_infomask));
|
|
|
|
xmax = HeapTupleGetUpdateXid(tuple);
|
|
|
|
/* not LOCKED_ONLY, so it has to have an xmax */
|
|
Assert(TransactionIdIsValid(xmax));
|
|
|
|
if (TransactionIdIsCurrentTransactionId(xmax))
|
|
{
|
|
if (HeapTupleHeaderGetCmax(tuple) >= snapshot->curcid)
|
|
return true; /* deleted after scan started */
|
|
else
|
|
return false; /* deleted before scan started */
|
|
}
|
|
if (XidInMVCCSnapshot(xmax, snapshot))
|
|
return true;
|
|
if (TransactionIdDidCommit(xmax))
|
|
return false; /* updating transaction committed */
|
|
/* it must have aborted or crashed */
|
|
return true;
|
|
}
|
|
|
|
if (!(tuple->t_infomask & HEAP_XMAX_COMMITTED))
|
|
{
|
|
if (TransactionIdIsCurrentTransactionId(HeapTupleHeaderGetRawXmax(tuple)))
|
|
{
|
|
if (HeapTupleHeaderGetCmax(tuple) >= snapshot->curcid)
|
|
return true; /* deleted after scan started */
|
|
else
|
|
return false; /* deleted before scan started */
|
|
}
|
|
|
|
if (XidInMVCCSnapshot(HeapTupleHeaderGetRawXmax(tuple), snapshot))
|
|
return true;
|
|
|
|
if (!TransactionIdDidCommit(HeapTupleHeaderGetRawXmax(tuple)))
|
|
{
|
|
/* it must have aborted or crashed */
|
|
SetHintBits(tuple, buffer, HEAP_XMAX_INVALID,
|
|
InvalidTransactionId);
|
|
return true;
|
|
}
|
|
|
|
/* xmax transaction committed */
|
|
SetHintBits(tuple, buffer, HEAP_XMAX_COMMITTED,
|
|
HeapTupleHeaderGetRawXmax(tuple));
|
|
}
|
|
else
|
|
{
|
|
/* xmax is committed, but maybe not according to our snapshot */
|
|
if (XidInMVCCSnapshot(HeapTupleHeaderGetRawXmax(tuple), snapshot))
|
|
return true; /* treat as still in progress */
|
|
}
|
|
|
|
/* xmax transaction committed */
|
|
|
|
return false;
|
|
}
|
|
|
|
|
|
/*
|
|
* HeapTupleSatisfiesVacuum
|
|
*
|
|
* Determine the status of tuples for VACUUM purposes. Here, what
|
|
* we mainly want to know is if a tuple is potentially visible to *any*
|
|
* running transaction. If so, it can't be removed yet by VACUUM.
|
|
*
|
|
* OldestXmin is a cutoff XID (obtained from GetOldestXmin()). Tuples
|
|
* deleted by XIDs >= OldestXmin are deemed "recently dead"; they might
|
|
* still be visible to some open transaction, so we can't remove them,
|
|
* even if we see that the deleting transaction has committed.
|
|
*/
|
|
HTSV_Result
|
|
HeapTupleSatisfiesVacuum(HeapTuple htup, TransactionId OldestXmin,
|
|
Buffer buffer)
|
|
{
|
|
HeapTupleHeader tuple = htup->t_data;
|
|
|
|
Assert(ItemPointerIsValid(&htup->t_self));
|
|
Assert(htup->t_tableOid != InvalidOid);
|
|
|
|
/*
|
|
* Has inserting transaction committed?
|
|
*
|
|
* If the inserting transaction aborted, then the tuple was never visible
|
|
* to any other transaction, so we can delete it immediately.
|
|
*/
|
|
if (!HeapTupleHeaderXminCommitted(tuple))
|
|
{
|
|
if (HeapTupleHeaderXminInvalid(tuple))
|
|
return HEAPTUPLE_DEAD;
|
|
/* Used by pre-9.0 binary upgrades */
|
|
else if (tuple->t_infomask & HEAP_MOVED_OFF)
|
|
{
|
|
TransactionId xvac = HeapTupleHeaderGetXvac(tuple);
|
|
|
|
if (TransactionIdIsCurrentTransactionId(xvac))
|
|
return HEAPTUPLE_DELETE_IN_PROGRESS;
|
|
if (TransactionIdIsInProgress(xvac))
|
|
return HEAPTUPLE_DELETE_IN_PROGRESS;
|
|
if (TransactionIdDidCommit(xvac))
|
|
{
|
|
SetHintBits(tuple, buffer, HEAP_XMIN_INVALID,
|
|
InvalidTransactionId);
|
|
return HEAPTUPLE_DEAD;
|
|
}
|
|
SetHintBits(tuple, buffer, HEAP_XMIN_COMMITTED,
|
|
InvalidTransactionId);
|
|
}
|
|
/* Used by pre-9.0 binary upgrades */
|
|
else if (tuple->t_infomask & HEAP_MOVED_IN)
|
|
{
|
|
TransactionId xvac = HeapTupleHeaderGetXvac(tuple);
|
|
|
|
if (TransactionIdIsCurrentTransactionId(xvac))
|
|
return HEAPTUPLE_INSERT_IN_PROGRESS;
|
|
if (TransactionIdIsInProgress(xvac))
|
|
return HEAPTUPLE_INSERT_IN_PROGRESS;
|
|
if (TransactionIdDidCommit(xvac))
|
|
SetHintBits(tuple, buffer, HEAP_XMIN_COMMITTED,
|
|
InvalidTransactionId);
|
|
else
|
|
{
|
|
SetHintBits(tuple, buffer, HEAP_XMIN_INVALID,
|
|
InvalidTransactionId);
|
|
return HEAPTUPLE_DEAD;
|
|
}
|
|
}
|
|
else if (TransactionIdIsCurrentTransactionId(HeapTupleHeaderGetRawXmin(tuple)))
|
|
{
|
|
if (tuple->t_infomask & HEAP_XMAX_INVALID) /* xid invalid */
|
|
return HEAPTUPLE_INSERT_IN_PROGRESS;
|
|
/* only locked? run infomask-only check first, for performance */
|
|
if (HEAP_XMAX_IS_LOCKED_ONLY(tuple->t_infomask) ||
|
|
HeapTupleHeaderIsOnlyLocked(tuple))
|
|
return HEAPTUPLE_INSERT_IN_PROGRESS;
|
|
/* inserted and then deleted by same xact */
|
|
if (TransactionIdIsCurrentTransactionId(HeapTupleHeaderGetUpdateXid(tuple)))
|
|
return HEAPTUPLE_DELETE_IN_PROGRESS;
|
|
/* deleting subtransaction must have aborted */
|
|
return HEAPTUPLE_INSERT_IN_PROGRESS;
|
|
}
|
|
else if (TransactionIdIsInProgress(HeapTupleHeaderGetRawXmin(tuple)))
|
|
{
|
|
/*
|
|
* It'd be possible to discern between INSERT/DELETE in progress
|
|
* here by looking at xmax - but that doesn't seem beneficial for
|
|
* the majority of callers and even detrimental for some. We'd
|
|
* rather have callers look at/wait for xmin than xmax. It's
|
|
* always correct to return INSERT_IN_PROGRESS because that's
|
|
* what's happening from the view of other backends.
|
|
*/
|
|
return HEAPTUPLE_INSERT_IN_PROGRESS;
|
|
}
|
|
else if (TransactionIdDidCommit(HeapTupleHeaderGetRawXmin(tuple)))
|
|
SetHintBits(tuple, buffer, HEAP_XMIN_COMMITTED,
|
|
HeapTupleHeaderGetRawXmin(tuple));
|
|
else
|
|
{
|
|
/*
|
|
* Not in Progress, Not Committed, so either Aborted or crashed
|
|
*/
|
|
SetHintBits(tuple, buffer, HEAP_XMIN_INVALID,
|
|
InvalidTransactionId);
|
|
return HEAPTUPLE_DEAD;
|
|
}
|
|
|
|
/*
|
|
* At this point the xmin is known committed, but we might not have
|
|
* been able to set the hint bit yet; so we can no longer Assert that
|
|
* it's set.
|
|
*/
|
|
}
|
|
|
|
/*
|
|
* Okay, the inserter committed, so it was good at some point. Now what
|
|
* about the deleting transaction?
|
|
*/
|
|
if (tuple->t_infomask & HEAP_XMAX_INVALID)
|
|
return HEAPTUPLE_LIVE;
|
|
|
|
if (HEAP_XMAX_IS_LOCKED_ONLY(tuple->t_infomask))
|
|
{
|
|
/*
|
|
* "Deleting" xact really only locked it, so the tuple is live in any
|
|
* case. However, we should make sure that either XMAX_COMMITTED or
|
|
* XMAX_INVALID gets set once the xact is gone, to reduce the costs of
|
|
* examining the tuple for future xacts.
|
|
*/
|
|
if (!(tuple->t_infomask & HEAP_XMAX_COMMITTED))
|
|
{
|
|
if (tuple->t_infomask & HEAP_XMAX_IS_MULTI)
|
|
{
|
|
/*
|
|
* If it's a pre-pg_upgrade tuple, the multixact cannot
|
|
* possibly be running; otherwise have to check.
|
|
*/
|
|
if (!HEAP_LOCKED_UPGRADED(tuple->t_infomask) &&
|
|
MultiXactIdIsRunning(HeapTupleHeaderGetRawXmax(tuple),
|
|
true))
|
|
return HEAPTUPLE_LIVE;
|
|
SetHintBits(tuple, buffer, HEAP_XMAX_INVALID, InvalidTransactionId);
|
|
}
|
|
else
|
|
{
|
|
if (TransactionIdIsInProgress(HeapTupleHeaderGetRawXmax(tuple)))
|
|
return HEAPTUPLE_LIVE;
|
|
SetHintBits(tuple, buffer, HEAP_XMAX_INVALID,
|
|
InvalidTransactionId);
|
|
}
|
|
}
|
|
|
|
/*
|
|
* We don't really care whether xmax did commit, abort or crash. We
|
|
* know that xmax did lock the tuple, but it did not and will never
|
|
* actually update it.
|
|
*/
|
|
|
|
return HEAPTUPLE_LIVE;
|
|
}
|
|
|
|
if (tuple->t_infomask & HEAP_XMAX_IS_MULTI)
|
|
{
|
|
TransactionId xmax = HeapTupleGetUpdateXid(tuple);
|
|
|
|
/* already checked above */
|
|
Assert(!HEAP_XMAX_IS_LOCKED_ONLY(tuple->t_infomask));
|
|
|
|
/* not LOCKED_ONLY, so it has to have an xmax */
|
|
Assert(TransactionIdIsValid(xmax));
|
|
|
|
if (TransactionIdIsInProgress(xmax))
|
|
return HEAPTUPLE_DELETE_IN_PROGRESS;
|
|
else if (TransactionIdDidCommit(xmax))
|
|
{
|
|
/*
|
|
* The multixact might still be running due to lockers. If the
|
|
* updater is below the xid horizon, we have to return DEAD
|
|
* regardless -- otherwise we could end up with a tuple where the
|
|
* updater has to be removed due to the horizon, but is not pruned
|
|
* away. It's not a problem to prune that tuple, because any
|
|
* remaining lockers will also be present in newer tuple versions.
|
|
*/
|
|
if (!TransactionIdPrecedes(xmax, OldestXmin))
|
|
return HEAPTUPLE_RECENTLY_DEAD;
|
|
|
|
return HEAPTUPLE_DEAD;
|
|
}
|
|
else if (!MultiXactIdIsRunning(HeapTupleHeaderGetRawXmax(tuple), false))
|
|
{
|
|
/*
|
|
* Not in Progress, Not Committed, so either Aborted or crashed.
|
|
* Mark the Xmax as invalid.
|
|
*/
|
|
SetHintBits(tuple, buffer, HEAP_XMAX_INVALID, InvalidTransactionId);
|
|
}
|
|
|
|
return HEAPTUPLE_LIVE;
|
|
}
|
|
|
|
if (!(tuple->t_infomask & HEAP_XMAX_COMMITTED))
|
|
{
|
|
if (TransactionIdIsInProgress(HeapTupleHeaderGetRawXmax(tuple)))
|
|
return HEAPTUPLE_DELETE_IN_PROGRESS;
|
|
else if (TransactionIdDidCommit(HeapTupleHeaderGetRawXmax(tuple)))
|
|
SetHintBits(tuple, buffer, HEAP_XMAX_COMMITTED,
|
|
HeapTupleHeaderGetRawXmax(tuple));
|
|
else
|
|
{
|
|
/*
|
|
* Not in Progress, Not Committed, so either Aborted or crashed
|
|
*/
|
|
SetHintBits(tuple, buffer, HEAP_XMAX_INVALID,
|
|
InvalidTransactionId);
|
|
return HEAPTUPLE_LIVE;
|
|
}
|
|
|
|
/*
|
|
* At this point the xmax is known committed, but we might not have
|
|
* been able to set the hint bit yet; so we can no longer Assert that
|
|
* it's set.
|
|
*/
|
|
}
|
|
|
|
/*
|
|
* Deleter committed, but perhaps it was recent enough that some open
|
|
* transactions could still see the tuple.
|
|
*/
|
|
if (!TransactionIdPrecedes(HeapTupleHeaderGetRawXmax(tuple), OldestXmin))
|
|
return HEAPTUPLE_RECENTLY_DEAD;
|
|
|
|
/* Otherwise, it's dead and removable */
|
|
return HEAPTUPLE_DEAD;
|
|
}
|
|
|
|
|
|
/*
|
|
* HeapTupleSatisfiesNonVacuumable
|
|
*
|
|
* True if tuple might be visible to some transaction; false if it's
|
|
* surely dead to everyone, ie, vacuumable.
|
|
*
|
|
* See SNAPSHOT_TOAST's definition for the intended behaviour.
|
|
*
|
|
* This is an interface to HeapTupleSatisfiesVacuum that's callable via
|
|
* HeapTupleSatisfiesSnapshot, so it can be used through a Snapshot.
|
|
* snapshot->xmin must have been set up with the xmin horizon to use.
|
|
*/
|
|
static bool
|
|
HeapTupleSatisfiesNonVacuumable(HeapTuple htup, Snapshot snapshot,
|
|
Buffer buffer)
|
|
{
|
|
return HeapTupleSatisfiesVacuum(htup, snapshot->xmin, buffer)
|
|
!= HEAPTUPLE_DEAD;
|
|
}
|
|
|
|
|
|
/*
|
|
* HeapTupleIsSurelyDead
|
|
*
|
|
* Cheaply determine whether a tuple is surely dead to all onlookers.
|
|
* We sometimes use this in lieu of HeapTupleSatisfiesVacuum when the
|
|
* tuple has just been tested by another visibility routine (usually
|
|
* HeapTupleSatisfiesMVCC) and, therefore, any hint bits that can be set
|
|
* should already be set. We assume that if no hint bits are set, the xmin
|
|
* or xmax transaction is still running. This is therefore faster than
|
|
* HeapTupleSatisfiesVacuum, because we don't consult PGXACT nor CLOG.
|
|
* It's okay to return false when in doubt, but we must return true only
|
|
* if the tuple is removable.
|
|
*/
|
|
bool
|
|
HeapTupleIsSurelyDead(HeapTuple htup, TransactionId OldestXmin)
|
|
{
|
|
HeapTupleHeader tuple = htup->t_data;
|
|
|
|
Assert(ItemPointerIsValid(&htup->t_self));
|
|
Assert(htup->t_tableOid != InvalidOid);
|
|
|
|
/*
|
|
* If the inserting transaction is marked invalid, then it aborted, and
|
|
* the tuple is definitely dead. If it's marked neither committed nor
|
|
* invalid, then we assume it's still alive (since the presumption is that
|
|
* all relevant hint bits were just set moments ago).
|
|
*/
|
|
if (!HeapTupleHeaderXminCommitted(tuple))
|
|
return HeapTupleHeaderXminInvalid(tuple) ? true : false;
|
|
|
|
/*
|
|
* If the inserting transaction committed, but any deleting transaction
|
|
* aborted, the tuple is still alive.
|
|
*/
|
|
if (tuple->t_infomask & HEAP_XMAX_INVALID)
|
|
return false;
|
|
|
|
/*
|
|
* If the XMAX is just a lock, the tuple is still alive.
|
|
*/
|
|
if (HEAP_XMAX_IS_LOCKED_ONLY(tuple->t_infomask))
|
|
return false;
|
|
|
|
/*
|
|
* If the Xmax is a MultiXact, it might be dead or alive, but we cannot
|
|
* know without checking pg_multixact.
|
|
*/
|
|
if (tuple->t_infomask & HEAP_XMAX_IS_MULTI)
|
|
return false;
|
|
|
|
/* If deleter isn't known to have committed, assume it's still running. */
|
|
if (!(tuple->t_infomask & HEAP_XMAX_COMMITTED))
|
|
return false;
|
|
|
|
/* Deleter committed, so tuple is dead if the XID is old enough. */
|
|
return TransactionIdPrecedes(HeapTupleHeaderGetRawXmax(tuple), OldestXmin);
|
|
}
|
|
|
|
/*
|
|
* Is the tuple really only locked? That is, is it not updated?
|
|
*
|
|
* It's easy to check just infomask bits if the locker is not a multi; but
|
|
* otherwise we need to verify that the updating transaction has not aborted.
|
|
*
|
|
* This function is here because it follows the same visibility rules laid out
|
|
* at the top of this file.
|
|
*/
|
|
bool
|
|
HeapTupleHeaderIsOnlyLocked(HeapTupleHeader tuple)
|
|
{
|
|
TransactionId xmax;
|
|
|
|
/* if there's no valid Xmax, then there's obviously no update either */
|
|
if (tuple->t_infomask & HEAP_XMAX_INVALID)
|
|
return true;
|
|
|
|
if (tuple->t_infomask & HEAP_XMAX_LOCK_ONLY)
|
|
return true;
|
|
|
|
/* invalid xmax means no update */
|
|
if (!TransactionIdIsValid(HeapTupleHeaderGetRawXmax(tuple)))
|
|
return true;
|
|
|
|
/*
|
|
* if HEAP_XMAX_LOCK_ONLY is not set and not a multi, then this must
|
|
* necessarily have been updated
|
|
*/
|
|
if (!(tuple->t_infomask & HEAP_XMAX_IS_MULTI))
|
|
return false;
|
|
|
|
/* ... but if it's a multi, then perhaps the updating Xid aborted. */
|
|
xmax = HeapTupleGetUpdateXid(tuple);
|
|
|
|
/* not LOCKED_ONLY, so it has to have an xmax */
|
|
Assert(TransactionIdIsValid(xmax));
|
|
|
|
if (TransactionIdIsCurrentTransactionId(xmax))
|
|
return false;
|
|
if (TransactionIdIsInProgress(xmax))
|
|
return false;
|
|
if (TransactionIdDidCommit(xmax))
|
|
return false;
|
|
|
|
/*
|
|
* not current, not in progress, not committed -- must have aborted or
|
|
* crashed
|
|
*/
|
|
return true;
|
|
}
|
|
|
|
/*
|
|
* check whether the transaction id 'xid' is in the pre-sorted array 'xip'.
|
|
*/
|
|
static bool
|
|
TransactionIdInArray(TransactionId xid, TransactionId *xip, Size num)
|
|
{
|
|
return bsearch(&xid, xip, num,
|
|
sizeof(TransactionId), xidComparator) != NULL;
|
|
}
|
|
|
|
/*
|
|
* See the comments for HeapTupleSatisfiesMVCC for the semantics this function
|
|
* obeys.
|
|
*
|
|
* Only usable on tuples from catalog tables!
|
|
*
|
|
* We don't need to support HEAP_MOVED_(IN|OFF) for now because we only support
|
|
* reading catalog pages which couldn't have been created in an older version.
|
|
*
|
|
* We don't set any hint bits in here as it seems unlikely to be beneficial as
|
|
* those should already be set by normal access and it seems to be too
|
|
* dangerous to do so as the semantics of doing so during timetravel are more
|
|
* complicated than when dealing "only" with the present.
|
|
*/
|
|
static bool
|
|
HeapTupleSatisfiesHistoricMVCC(HeapTuple htup, Snapshot snapshot,
|
|
Buffer buffer)
|
|
{
|
|
HeapTupleHeader tuple = htup->t_data;
|
|
TransactionId xmin = HeapTupleHeaderGetXmin(tuple);
|
|
TransactionId xmax = HeapTupleHeaderGetRawXmax(tuple);
|
|
|
|
Assert(ItemPointerIsValid(&htup->t_self));
|
|
Assert(htup->t_tableOid != InvalidOid);
|
|
|
|
/* inserting transaction aborted */
|
|
if (HeapTupleHeaderXminInvalid(tuple))
|
|
{
|
|
Assert(!TransactionIdDidCommit(xmin));
|
|
return false;
|
|
}
|
|
/* check if it's one of our txids, toplevel is also in there */
|
|
else if (TransactionIdInArray(xmin, snapshot->subxip, snapshot->subxcnt))
|
|
{
|
|
bool resolved;
|
|
CommandId cmin = HeapTupleHeaderGetRawCommandId(tuple);
|
|
CommandId cmax = InvalidCommandId;
|
|
|
|
/*
|
|
* another transaction might have (tried to) delete this tuple or
|
|
* cmin/cmax was stored in a combocid. So we need to lookup the actual
|
|
* values externally.
|
|
*/
|
|
resolved = ResolveCminCmaxDuringDecoding(HistoricSnapshotGetTupleCids(), snapshot,
|
|
htup, buffer,
|
|
&cmin, &cmax);
|
|
|
|
if (!resolved)
|
|
elog(ERROR, "could not resolve cmin/cmax of catalog tuple");
|
|
|
|
Assert(cmin != InvalidCommandId);
|
|
|
|
if (cmin >= snapshot->curcid)
|
|
return false; /* inserted after scan started */
|
|
/* fall through */
|
|
}
|
|
/* committed before our xmin horizon. Do a normal visibility check. */
|
|
else if (TransactionIdPrecedes(xmin, snapshot->xmin))
|
|
{
|
|
Assert(!(HeapTupleHeaderXminCommitted(tuple) &&
|
|
!TransactionIdDidCommit(xmin)));
|
|
|
|
/* check for hint bit first, consult clog afterwards */
|
|
if (!HeapTupleHeaderXminCommitted(tuple) &&
|
|
!TransactionIdDidCommit(xmin))
|
|
return false;
|
|
/* fall through */
|
|
}
|
|
/* beyond our xmax horizon, i.e. invisible */
|
|
else if (TransactionIdFollowsOrEquals(xmin, snapshot->xmax))
|
|
{
|
|
return false;
|
|
}
|
|
/* check if it's a committed transaction in [xmin, xmax) */
|
|
else if (TransactionIdInArray(xmin, snapshot->xip, snapshot->xcnt))
|
|
{
|
|
/* fall through */
|
|
}
|
|
|
|
/*
|
|
* none of the above, i.e. between [xmin, xmax) but hasn't committed. I.e.
|
|
* invisible.
|
|
*/
|
|
else
|
|
{
|
|
return false;
|
|
}
|
|
|
|
/* at this point we know xmin is visible, go on to check xmax */
|
|
|
|
/* xid invalid or aborted */
|
|
if (tuple->t_infomask & HEAP_XMAX_INVALID)
|
|
return true;
|
|
/* locked tuples are always visible */
|
|
else if (HEAP_XMAX_IS_LOCKED_ONLY(tuple->t_infomask))
|
|
return true;
|
|
|
|
/*
|
|
* We can see multis here if we're looking at user tables or if somebody
|
|
* SELECT ... FOR SHARE/UPDATE a system table.
|
|
*/
|
|
else if (tuple->t_infomask & HEAP_XMAX_IS_MULTI)
|
|
{
|
|
xmax = HeapTupleGetUpdateXid(tuple);
|
|
}
|
|
|
|
/* check if it's one of our txids, toplevel is also in there */
|
|
if (TransactionIdInArray(xmax, snapshot->subxip, snapshot->subxcnt))
|
|
{
|
|
bool resolved;
|
|
CommandId cmin;
|
|
CommandId cmax = HeapTupleHeaderGetRawCommandId(tuple);
|
|
|
|
/* Lookup actual cmin/cmax values */
|
|
resolved = ResolveCminCmaxDuringDecoding(HistoricSnapshotGetTupleCids(), snapshot,
|
|
htup, buffer,
|
|
&cmin, &cmax);
|
|
|
|
if (!resolved)
|
|
elog(ERROR, "could not resolve combocid to cmax");
|
|
|
|
Assert(cmax != InvalidCommandId);
|
|
|
|
if (cmax >= snapshot->curcid)
|
|
return true; /* deleted after scan started */
|
|
else
|
|
return false; /* deleted before scan started */
|
|
}
|
|
/* below xmin horizon, normal transaction state is valid */
|
|
else if (TransactionIdPrecedes(xmax, snapshot->xmin))
|
|
{
|
|
Assert(!(tuple->t_infomask & HEAP_XMAX_COMMITTED &&
|
|
!TransactionIdDidCommit(xmax)));
|
|
|
|
/* check hint bit first */
|
|
if (tuple->t_infomask & HEAP_XMAX_COMMITTED)
|
|
return false;
|
|
|
|
/* check clog */
|
|
return !TransactionIdDidCommit(xmax);
|
|
}
|
|
/* above xmax horizon, we cannot possibly see the deleting transaction */
|
|
else if (TransactionIdFollowsOrEquals(xmax, snapshot->xmax))
|
|
return true;
|
|
/* xmax is between [xmin, xmax), check known committed array */
|
|
else if (TransactionIdInArray(xmax, snapshot->xip, snapshot->xcnt))
|
|
return false;
|
|
/* xmax is between [xmin, xmax), but known not to have committed yet */
|
|
else
|
|
return true;
|
|
}
|
|
|
|
/*
|
|
* HeapTupleSatisfiesVisibility
|
|
* True iff heap tuple satisfies a time qual.
|
|
*
|
|
* Notes:
|
|
* Assumes heap tuple is valid, and buffer at least share locked.
|
|
*
|
|
* Hint bits in the HeapTuple's t_infomask may be updated as a side effect;
|
|
* if so, the indicated buffer is marked dirty.
|
|
*/
|
|
bool
|
|
HeapTupleSatisfiesVisibility(HeapTuple tup, Snapshot snapshot, Buffer buffer)
|
|
{
|
|
switch (snapshot->snapshot_type)
|
|
{
|
|
case SNAPSHOT_MVCC:
|
|
return HeapTupleSatisfiesMVCC(tup, snapshot, buffer);
|
|
break;
|
|
case SNAPSHOT_SELF:
|
|
return HeapTupleSatisfiesSelf(tup, snapshot, buffer);
|
|
break;
|
|
case SNAPSHOT_ANY:
|
|
return HeapTupleSatisfiesAny(tup, snapshot, buffer);
|
|
break;
|
|
case SNAPSHOT_TOAST:
|
|
return HeapTupleSatisfiesToast(tup, snapshot, buffer);
|
|
break;
|
|
case SNAPSHOT_DIRTY:
|
|
return HeapTupleSatisfiesDirty(tup, snapshot, buffer);
|
|
break;
|
|
case SNAPSHOT_HISTORIC_MVCC:
|
|
return HeapTupleSatisfiesHistoricMVCC(tup, snapshot, buffer);
|
|
break;
|
|
case SNAPSHOT_NON_VACUUMABLE:
|
|
return HeapTupleSatisfiesNonVacuumable(tup, snapshot, buffer);
|
|
break;
|
|
}
|
|
|
|
return false; /* keep compiler quiet */
|
|
}
|