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Fix incremental backup interaction with XLOG_DBASE_CREATE_FILE_COPY.

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After XLOG_DBASE_CREATE_FILE_COPY, a correct incremental backup needs
to copy in full everything with the database and tablespace OID
mentioned in that record; but that record doesn't specifically mention
the blocks, or even the relfilenumbers, of the affected relations.
As a result, we were failing to copy data that we should have copied.

To fix, enter the DB OID and tablespace OID into the block reference
table with relfilenumber 0 and limit block 0; and treat that as a
limit block of 0 for every relfilenumber whose DB OID and tablespace
OID match.

Also, add a test case.

Patch by me, reviewed by Noah Misch.

Discussion: http://postgr.es/m/CA+Tgmob0xa=ByvGLMdAgkUZyVQE=r4nyYZ_VEa40FCfEDFnTKA@mail.gmail.com
This commit is contained in:
Robert Haas
2024-03-04 13:33:12 -05:00
parent cb6945dc80
commit d75c4027b6
4 changed files with 151 additions and 1 deletions
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75
src/backend/postmaster/walsummarizer.c
View File

@@ -29,6 +29,7 @@
#include "access/xlogutils.h"
#include "backup/walsummary.h"
#include "catalog/storage_xlog.h"
#include "commands/dbcommands_xlog.h"
#include "common/blkreftable.h"
#include "libpq/pqsignal.h"
#include "miscadmin.h"
@@ -146,6 +147,8 @@ static void HandleWalSummarizerInterrupts(void);
static XLogRecPtr SummarizeWAL(TimeLineID tli, XLogRecPtr start_lsn,
bool exact, XLogRecPtr switch_lsn,
XLogRecPtr maximum_lsn);
static void SummarizeDbaseRecord(XLogReaderState *xlogreader,
BlockRefTable *brtab);
static void SummarizeSmgrRecord(XLogReaderState *xlogreader,
BlockRefTable *brtab);
static void SummarizeXactRecord(XLogReaderState *xlogreader,
@@ -961,6 +964,9 @@ SummarizeWAL(TimeLineID tli, XLogRecPtr start_lsn, bool exact,
/* Special handling for particular types of WAL records. */
switch (XLogRecGetRmid(xlogreader))
{
case RM_DBASE_ID:
SummarizeDbaseRecord(xlogreader, brtab);
break;
case RM_SMGR_ID:
SummarizeSmgrRecord(xlogreader, brtab);
break;
@@ -1074,6 +1080,75 @@ SummarizeWAL(TimeLineID tli, XLogRecPtr start_lsn, bool exact,
return summary_end_lsn;
}
/*
* Special handling for WAL records with RM_DBASE_ID.
*/
static void
SummarizeDbaseRecord(XLogReaderState *xlogreader, BlockRefTable *brtab)
{
uint8 info = XLogRecGetInfo(xlogreader) & ~XLR_INFO_MASK;
/*
* We use relfilenode zero for a given database OID and tablespace OID
* to indicate that all relations with that pair of IDs have been
* recreated if they exist at all. Effectively, we're setting a limit
* block of 0 for all such relfilenodes.
*
* Technically, this special handling is only needed in the case of
* XLOG_DBASE_CREATE_FILE_COPY, because that can create a whole bunch
* of relation files in a directory without logging anything
* specific to each one. If we didn't mark the whole DB OID/TS OID
* combination in some way, then a tablespace that was dropped after
* the reference backup and recreated using the FILE_COPY method prior
* to the incremental backup would look just like one that was never
* touched at all, which would be catastrophic.
*
* But it seems best to adopt this treatment for all records that drop
* or create a DB OID/TS OID combination. That's similar to how we
* treat the limit block for individual relations, and it's an extra
* layer of safety here. We can never lose data by marking more stuff
* as needing to be backed up in full.
*/
if (info == XLOG_DBASE_CREATE_FILE_COPY)
{
xl_dbase_create_file_copy_rec *xlrec;
RelFileLocator rlocator;
xlrec =
(xl_dbase_create_file_copy_rec *) XLogRecGetData(xlogreader);
rlocator.spcOid = xlrec->tablespace_id;
rlocator.dbOid = xlrec->db_id;
rlocator.relNumber = 0;
BlockRefTableSetLimitBlock(brtab, &rlocator, MAIN_FORKNUM, 0);
}
else if (info == XLOG_DBASE_CREATE_WAL_LOG)
{
xl_dbase_create_wal_log_rec *xlrec;
RelFileLocator rlocator;
xlrec = (xl_dbase_create_wal_log_rec *) XLogRecGetData(xlogreader);
rlocator.spcOid = xlrec->tablespace_id;
rlocator.dbOid = xlrec->db_id;
rlocator.relNumber = 0;
BlockRefTableSetLimitBlock(brtab, &rlocator, MAIN_FORKNUM, 0);
}
else if (info == XLOG_DBASE_DROP)
{
xl_dbase_drop_rec *xlrec;
RelFileLocator rlocator;
int i;
xlrec = (xl_dbase_drop_rec *) XLogRecGetData(xlogreader);
rlocator.dbOid = xlrec->db_id;
rlocator.relNumber = 0;
for (i = 0; i < xlrec->ntablespaces; ++i)
{
rlocator.spcOid = xlrec->tablespace_ids[i];
BlockRefTableSetLimitBlock(brtab, &rlocator, MAIN_FORKNUM, 0);
}
}
}
/*
* Special handling for WAL records with RM_SMGR_ID.
*/