On 2013-04-01 19:51:19 -0700, Jeff Janes wrote:
> On Mon, Apr 1, 2013 at 10:37 AM, Jeff Janes <jeff.ja...@gmail.com> wrote:
>
> > On Tue, Mar 26, 2013 at 4:23 PM, Jeff Davis <pg...@j-davis.com> wrote:
> >
> >>
> >> Patch attached. Only brief testing done, so I might have missed
> >> something. I will look more closely later.
> >>
> >
> > After applying your patch, I could run the stress test described here:
> >
> > http://archives.postgresql.org/pgsql-hackers/2012-02/msg01227.php
> >
> > But altered to make use of initdb -k, of course.
> >
> > Over 10,000 cycles of crash and recovery, I encountered two cases of
> > checksum failures after recovery, example:
> > ...
> >
>
>
> > Unfortunately I already cleaned up the data directory before noticing the
> > problem, so I have nothing to post for forensic analysis. I'll try to
> > reproduce the problem.
> >
> >
> I've reproduced the problem, this time in block 74 of relation
> base/16384/4931589, and a tarball of the data directory is here:
>
> https://docs.google.com/file/d/0Bzqrh1SO9FcELS1majlFcTZsR0k/edit?usp=sharing
>
> (the table is in database jjanes under role jjanes, the binary is commit
> 9ad27c215362df436f8c)
>
> What I would probably really want is the data as it existed after the crash
> but before recovery started, but since the postmaster immediately starts
> recovery after the crash, I don't know of a good way to capture this.
>
> I guess one thing to do would be to extract from the WAL the most recent
> FPW for block 74 of relation base/16384/4931589 (assuming it hasn't been
> recycled already) and see if it matches what is actually in that block of
> that data file, but I don't currently know how to do that.
Since I bragged somewhere else recently that it should be easy to do now that
we have pg_xlogdump I hacked it up so it dumps all the full page writes into
the directory specified by --dump-bkp=PATH. It currently overwrites previous
full page writes to the same page but that should be trivial to change if you
want by adding %X.%X for the lsn into the path sprintf.
Greetings,
Andres Freund
--
Andres Freund http://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Training & Services
>From 09cdce611dc74082901ca1a646135a5ea1af709c Mon Sep 17 00:00:00 2001
From: Andres Freund <and...@anarazel.de>
Date: Tue, 2 Apr 2013 11:43:23 +0200
Subject: [PATCH] pg_xlogdump: add option for dumping full page writes into a
directory
---
contrib/pg_xlogdump/pg_xlogdump.c | 56 ++++++++++++++++++++++++++++++++++++-
1 file changed, 55 insertions(+), 1 deletion(-)
diff --git a/contrib/pg_xlogdump/pg_xlogdump.c b/contrib/pg_xlogdump/pg_xlogdump.c
index d6d5498..a5e4186 100644
--- a/contrib/pg_xlogdump/pg_xlogdump.c
+++ b/contrib/pg_xlogdump/pg_xlogdump.c
@@ -40,6 +40,7 @@ typedef struct XLogDumpConfig
bool bkp_details;
int stop_after_records;
int already_displayed_records;
+ char *dump_bkp;
/* filter options */
int filter_by_rmgr;
@@ -373,6 +374,46 @@ XLogDumpDisplayRecord(XLogDumpConfig *config, XLogRecPtr ReadRecPtr, XLogRecord
bkpb.block, bkpb.hole_offset, bkpb.hole_length);
}
}
+
+ if (config->dump_bkp != NULL)
+ {
+ int bkpnum;
+ char *blk = (char *) XLogRecGetData(record) + record->xl_len;
+
+ for (bkpnum = 0; bkpnum < XLR_MAX_BKP_BLOCKS; bkpnum++)
+ {
+ BkpBlock bkpb;
+ char bkpbdata[BLCKSZ];
+ int outfd;
+ char outpath[MAXPGPATH];
+
+ if (!(XLR_BKP_BLOCK(bkpnum) & record->xl_info))
+ continue;
+
+ memcpy(&bkpb, blk, sizeof(BkpBlock));
+ blk += sizeof(BkpBlock);
+
+ memcpy(bkpbdata, blk, bkpb.hole_offset);
+ memset(bkpbdata + bkpb.hole_offset, 0, bkpb.hole_length);
+ memcpy(bkpbdata + bkpb.hole_offset + bkpb.hole_length,
+ blk + bkpb.hole_offset,
+ BLCKSZ - bkpb.hole_offset - bkpb.hole_length);
+
+ blk += BLCKSZ - bkpb.hole_length;
+
+ sprintf(outpath, "%s/%u-%u-%u:%u_%s", config->dump_bkp,
+ bkpb.node.spcNode, bkpb.node.dbNode, bkpb.node.relNode,
+ bkpb.block, forkNames[bkpb.fork]);
+ outfd = open(outpath, O_WRONLY|O_TRUNC|O_CREAT, S_IRUSR|S_IWUSR);
+ if (outfd < 0)
+ fatal_error("could not open output file %s: %s",
+ outpath, strerror(errno));
+ if (write(outfd, bkpbdata, BLCKSZ) != BLCKSZ)
+ fatal_error("could not successfully write output block %s: %s",
+ outpath, strerror(errno));
+ close(outfd);
+ }
+ }
}
static void
@@ -387,6 +428,7 @@ usage(void)
printf(" -?, --help show this help, then exit\n");
printf("\nContent options:\n");
printf(" -b, --bkp-details output detailed information about backup blocks\n");
+ printf(" -d, --dump-bkp=path dump all full page images into PATH\n");
printf(" -e, --end=RECPTR stop reading at log position RECPTR\n");
printf(" -n, --limit=N number of records to display\n");
printf(" -p, --path=PATH directory in which to find log segment files\n");
@@ -413,6 +455,7 @@ main(int argc, char **argv)
static struct option long_options[] = {
{"bkp-details", no_argument, NULL, 'b'},
+ {"dump-bkp", required_argument, NULL, 'd'},
{"end", required_argument, NULL, 'e'},
{"help", no_argument, NULL, '?'},
{"limit", required_argument, NULL, 'n'},
@@ -438,6 +481,7 @@ main(int argc, char **argv)
private.endptr = InvalidXLogRecPtr;
config.bkp_details = false;
+ config.dump_bkp = NULL;
config.stop_after_records = -1;
config.already_displayed_records = 0;
config.filter_by_rmgr = -1;
@@ -450,7 +494,7 @@ main(int argc, char **argv)
goto bad_argument;
}
- while ((option = getopt_long(argc, argv, "be:?n:p:r:s:t:Vx:",
+ while ((option = getopt_long(argc, argv, "bd:e:?n:p:r:s:t:Vx:",
long_options, &optindex)) != -1)
{
switch (option)
@@ -458,6 +502,16 @@ main(int argc, char **argv)
case 'b':
config.bkp_details = true;
break;
+ case 'd':
+ config.dump_bkp = pg_strdup(optarg);
+ if (!verify_directory(config.dump_bkp))
+ {
+ fprintf(stderr,
+ "%s: path \"%s\" cannot be opened: %s",
+ progname, config.dump_bkp, strerror(errno));
+ goto bad_argument;
+ }
+ break;
case 'e':
if (sscanf(optarg, "%X/%X", &xlogid, &xrecoff) != 2)
{
--
1.7.10.4
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