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Fix failure to delete spill files of aborted transactions

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Logical decoding's reorderbuffer.c may spill transaction files to disk
when transactions are large.  These are supposed to be removed when they
become "too old" by xid; but file removal requires the boundary LSNs of
the transaction to be known.  The final_lsn is only set when we see the
commit or abort record for the transaction, but nothing sets the value
for transactions that crash, so the removal code misbehaves -- in
assertion-enabled builds, it crashes by a failed assertion.

To fix, modify the final_lsn of transactions that don't have a value
set, to the LSN of the very latest change in the transaction.  This
causes the spilled files to be removed appropriately.

Author: Atsushi Torikoshi
Reviewed-by: Kyotaro HORIGUCHI, Craig Ringer, Masahiko Sawada
Discussion: https://postgr.es/m/54e4e488-186b-a056-6628-50628e4e4ebc@lab.ntt.co.jp
This commit is contained in:
Alvaro Herrera 2018-01-05 12:17:10 -03:00
parent 054e8c6cdb
commit df9f682c7b
2 changed files with 19 additions and 2 deletions
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19
src/backend/replication/logical/reorderbuffer.c
View File

@ -1670,8 +1670,8 @@ ReorderBufferAbortOld(ReorderBuffer *rb, TransactionId oldestRunningXid)
* Iterate through all (potential) toplevel TXNs and abort all that are
* older than what possibly can be running. Once we've found the first
* that is alive we stop, there might be some that acquired an xid earlier
* but started writing later, but it's unlikely and they will cleaned up
* in a later call to ReorderBufferAbortOld().
* but started writing later, but it's unlikely and they will be cleaned
* up in a later call to this function.
*/
dlist_foreach_modify(it, &rb->toplevel_by_lsn)
{
@ -1681,6 +1681,21 @@ ReorderBufferAbortOld(ReorderBuffer *rb, TransactionId oldestRunningXid)
if (TransactionIdPrecedes(txn->xid, oldestRunningXid))
{
/*
* We set final_lsn on a transaction when we decode its commit or
* abort record, but we never see those records for crashed
* transactions. To ensure cleanup of these transactions, set
* final_lsn to that of their last change; this causes
* ReorderBufferRestoreCleanup to do the right thing.
*/
if (txn->serialized && txn->final_lsn == 0)
{
ReorderBufferChange *last =
dlist_tail_element(ReorderBufferChange, node, &txn->changes);
txn->final_lsn = last->lsn;
}
elog(DEBUG2, "aborting old transaction %u", txn->xid);
/* remove potential on-disk data, and deallocate this tx */

2
src/include/replication/reorderbuffer.h
View File

@ -168,6 +168,8 @@ typedef struct ReorderBufferTXN
* * plain abort record
* * prepared transaction abort
* * error during decoding
* * for a crashed transaction, the LSN of the last change, regardless of
* what it was.
* ----
*/
XLogRecPtr final_lsn;