pg.ddx.io pgsql-hackers@postgresql.org mailing list archive help / color / mirror / Atom feed From: movead.li@highgo.ca <movead.li@highgo.ca>
To: Horiguchi <horikyota.ntt@gmail.com>
Cc: pgsql-hackers <pgsql-hackers@postgresql.org>
Cc: ahsan.hadi <ahsan.hadi@highgo.ca>
Subject: Re: Wrong statistics for size of XLOG_SWITCH during pg_waldump.
Date: Sat, 10 Oct 2020 09:50:02 +0800
Message-ID: <2020101009495929215052@highgo.ca> (raw )
References: <2020100913412132258847@highgo.ca >
<20201009.174658.2098946247926431018.horikyota.ntt@gmail.com >
>I think that the length of the XLOG_SWITCH record is no other than 24
>bytes. Just adding the padding? garbage bytes to that length doesn't
>seem the right thing to me.
>
>If we want pg_waldump to show that length somewhere, it could be shown
>at the end of that record explicitly:
>
>rmgr: XLOG len (rec/tot): 24/16776848, tx: 0, lsn: 0/02000148, prev 0/02000110, desc: SWITCH, trailing-bytes: 16776944
Thanks, I think it's good idea, and new patch attached.
Here's the lookes:
rmgr: XLOG len (rec/tot): 24/ 24, tx: 0, lsn: 0/030000D8, prev 0/03000060, desc: SWITCH, trailing-bytes: 16776936
Regards,
Highgo Software (Canada/China/Pakistan)
URL : www.highgo.ca
EMAIL: mailto:movead(dot)li(at)highgo(dot)ca
Attachments:
fix_waldump_size_for_wal_switch_v2.patch (application/octet-stream, 3.6K) download
diff --git a/src/bin/pg_waldump/pg_waldump.c b/src/bin/pg_waldump/pg_waldump.c
index 31e99c2a6d..30159cc820 100644
--- a/src/bin/pg_waldump/pg_waldump.c
+++ b/src/bin/pg_waldump/pg_waldump.c
@@ -24,6 +24,7 @@
#include "common/logging.h"
#include "getopt_long.h"
#include "rmgrdesc.h"
+#include "catalog/pg_control.h"
static const char *progname;
@@ -380,9 +381,11 @@ WALDumpReadPage(XLogReaderState *state, XLogRecPtr targetPagePtr, int reqLen,
* Calculate the size of a record, split into !FPI and FPI parts.
*/
static void
-XLogDumpRecordLen(XLogReaderState *record, uint32 *rec_len, uint32 *fpi_len)
+XLogDumpRecordLen(XLogReaderState *record, uint32 *rec_len, uint32 *fpi_len, uint32 *junk_len)
{
int block_id;
+ RmgrId rmid;
+ uint8 info;
/*
* Calculate the amount of FPI data in the record.
@@ -403,6 +406,31 @@ XLogDumpRecordLen(XLogReaderState *record, uint32 *rec_len, uint32 *fpi_len)
* all the block images.
*/
*rec_len = XLogRecGetTotalLen(record) - *fpi_len;
+
+ rmid = XLogRecGetRmid(record);
+ info = XLogRecGetInfo(record) & ~XLR_INFO_MASK;
+
+ /*
+ * If it's a wal switch record, we should caculate the junk size which skipped
+ * by this record.
+ */
+ *junk_len = 0;
+ if(RM_XLOG_ID == rmid && XLOG_SWITCH == info)
+ {
+ XLogSegNo startSegNo;
+ XLogSegNo endSegNo;
+
+ XLByteToSeg(record->ReadRecPtr, startSegNo, record->segcxt.ws_segsize);
+ XLByteToSeg(record->EndRecPtr, endSegNo, record->segcxt.ws_segsize);
+
+ *junk_len = record->EndRecPtr - record->ReadRecPtr - XLogRecGetTotalLen(record);
+ /*
+ * If the wal switch record spread on two segments, we should extra minus the
+ * long page head.
+ */
+ if(startSegNo != endSegNo)
+ *junk_len -= SizeOfXLogLongPHD;
+ }
}
/*
@@ -416,12 +444,14 @@ XLogDumpCountRecord(XLogDumpConfig *config, XLogDumpStats *stats,
uint8 recid;
uint32 rec_len;
uint32 fpi_len;
+ uint32 junk_len;
stats->count++;
rmid = XLogRecGetRmid(record);
- XLogDumpRecordLen(record, &rec_len, &fpi_len);
+ XLogDumpRecordLen(record, &rec_len, &fpi_len, &junk_len);
+ rec_len += junk_len;
/* Update per-rmgr statistics */
@@ -435,9 +465,7 @@ XLogDumpCountRecord(XLogDumpConfig *config, XLogDumpStats *stats,
* are the rmgr's domain (resulting in sixteen possible entries per
* RmgrId).
*/
-
recid = XLogRecGetInfo(record) >> 4;
-
stats->record_stats[rmid][recid].count++;
stats->record_stats[rmid][recid].rec_len += rec_len;
stats->record_stats[rmid][recid].fpi_len += fpi_len;
@@ -453,6 +481,7 @@ XLogDumpDisplayRecord(XLogDumpConfig *config, XLogReaderState *record)
const RmgrDescData *desc = &RmgrDescTable[XLogRecGetRmid(record)];
uint32 rec_len;
uint32 fpi_len;
+ uint32 junk_len;
RelFileNode rnode;
ForkNumber forknum;
BlockNumber blk;
@@ -461,7 +490,7 @@ XLogDumpDisplayRecord(XLogDumpConfig *config, XLogReaderState *record)
XLogRecPtr xl_prev = XLogRecGetPrev(record);
StringInfoData s;
- XLogDumpRecordLen(record, &rec_len, &fpi_len);
+ XLogDumpRecordLen(record, &rec_len, &fpi_len, &junk_len);
printf("rmgr: %-11s len (rec/tot): %6u/%6u, tx: %10u, lsn: %X/%08X, prev %X/%08X, ",
desc->rm_name,
@@ -472,9 +501,15 @@ XLogDumpDisplayRecord(XLogDumpConfig *config, XLogReaderState *record)
id = desc->rm_identify(info);
if (id == NULL)
- printf("desc: UNKNOWN (%x) ", info & ~XLR_INFO_MASK);
+ printf("desc: UNKNOWN (%x)", info & ~XLR_INFO_MASK);
else
- printf("desc: %s ", id);
+ printf("desc: %s", id);
+
+ if(0 != junk_len)
+ {
+ printf(", trailing-bytes: %u", junk_len);
+ }
+ printf(" ");
initStringInfo(&s);
desc->rm_desc(&s, record);
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Permalink: ../2020101009495929215052@highgo.ca/
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To: pgsql-hackers@postgresql.org
Cc: movead.li@highgo.ca, horikyota.ntt@gmail.com, ahsan.hadi@highgo.ca
Subject: Re: Wrong statistics for size of XLOG_SWITCH during pg_waldump.
In-Reply-To: <2020101009495929215052@highgo.ca>
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