From: Masahiro Ikeda <ikedamsh@oss.nttdata.com>
To: Fujii Masao <masao.fujii@oss.nttdata.com>
Cc: pgsql-hackers <pgsql-hackers@postgresql.org>
Subject: Re: Add statistics to pg_stat_wal view for wal related parameter tuning
Date: Thu, 19 Nov 2020 16:31:09 +0900
Message-ID: <89de5056627ebdd144967959bd789bd6@oss.nttdata.com> (raw)
In-Reply-To: <79620b5c-ecf1-3d4f-80b5-7e311b7a0662@oss.nttdata.com>
References: <35ef960128b90bfae3b3fdf60a3a860f@oss.nttdata.com>
<a7e4a0b8-7341-9393-2d24-ffd9a3b2f852@oss.nttdata.com>
<e3135545ffe792d6d636ebc40ebf022d@oss.nttdata.com>
<e28c5f5e-363e-70c1-a200-28a8798ed8e2@oss.nttdata.com>
<11e81f0b7d90dd69077d3d964a9a4da9@oss.nttdata.com>
<79620b5c-ecf1-3d4f-80b5-7e311b7a0662@oss.nttdata.com>
On 2020-11-17 11:46, Fujii Masao wrote:
> On 2020/11/16 16:35, Masahiro Ikeda wrote:
>> On 2020-11-12 14:58, Fujii Masao wrote:
>>> On 2020/11/06 10:25, Masahiro Ikeda wrote:
>>>> On 2020-10-30 11:50, Fujii Masao wrote:
>>>>> On 2020/10/29 17:03, Masahiro Ikeda wrote:
>>>>>> Hi,
>>>>>>
>>>>>> Thanks for your comments and advice. I updated the patch.
>>>>>>
>>>>>> On 2020-10-21 18:03, Kyotaro Horiguchi wrote:
>>>>>>> At Tue, 20 Oct 2020 16:11:29 +0900, Masahiro Ikeda
>>>>>>> <ikedamsh@oss.nttdata.com> wrote in
>>>>>>>> On 2020-10-20 12:46, Amit Kapila wrote:
>>>>>>>> > I see that we also need to add extra code to capture these stats (some
>>>>>>>> > of which is in performance-critical path especially in
>>>>>>>> > XLogInsertRecord) which again makes me a bit uncomfortable. It might
>>>>>>>> > be that it is all fine as it is very important to collect these stats
>>>>>>>> > at cluster-level in spite that the same information can be gathered at
>>>>>>>> > statement-level to help customers but I don't see a very strong case
>>>>>>>> > for that in your proposal.
>>>>>>>
>>>>>>> We should avoid that duplication as possible even if the both
>>>>>>> number
>>>>>>> are important.
>>>>>>>
>>>>>>>> Also about performance, I thought there are few impacts because
>>>>>>>> it
>>>>>>>> increments stats in memory. If I can implement to reuse
>>>>>>>> pgWalUsage's
>>>>>>>> value which already collects these stats, there is no impact in
>>>>>>>> XLogInsertRecord.
>>>>>>>> For example, how about pg_stat_wal() calculates the accumulated
>>>>>>>> value of wal_records, wal_fpi, and wal_bytes to use pgWalUsage's
>>>>>>>> value?
>>>>>>>
>>>>>>> I don't think that works, but it would work that
>>>>>>> pgstat_send_wal()
>>>>>>> takes the difference of that values between two successive calls.
>>>>>>>
>>>>>>> WalUsage prevWalUsage;
>>>>>>> ...
>>>>>>> pgstat_send_wal()
>>>>>>> {
>>>>>>> ..
>>>>>>> /* fill in some values using pgWalUsage */
>>>>>>> WalStats.m_wal_bytes = pgWalUsage.wal_bytes -
>>>>>>> prevWalUsage.wal_bytes;
>>>>>>> WalStats.m_wal_records = pgWalUsage.wal_records -
>>>>>>> prevWalUsage.wal_records;
>>>>>>> WalStats.m_wal_wal_fpi = pgWalUsage.wal_fpi -
>>>>>>> prevWalUsage.wal_fpi;
>>>>>>> ...
>>>>>>> pgstat_send(&WalStats, sizeof(WalStats));
>>>>>>>
>>>>>>> /* remember the current numbers */
>>>>>>> prevWalUsage = pgWalUsage;
>>>>>>
>>>>>> Thanks for Horiguchi-san's advice, I changed to reuse pgWalUsage
>>>>>> which is already defined and eliminates the extra overhead.
>>>>>
>>>>> + /* fill in some values using pgWalUsage */
>>>>> + WalStats.m_wal_bytes = pgWalUsage.wal_bytes -
>>>>> prevWalUsage.wal_bytes;
>>>>> + WalStats.m_wal_records = pgWalUsage.wal_records -
>>>>> prevWalUsage.wal_records;
>>>>> + WalStats.m_wal_fpi = pgWalUsage.wal_fpi -
>>>>> prevWalUsage.wal_fpi;
>>>>>
>>>>> It's better to use WalUsageAccumDiff() here?
>>>>
>>>> Yes, thanks. I fixed it.
>>>>
>>>>> prevWalUsage needs to be initialized with pgWalUsage?
>>>>>
>>>>> + if (AmWalWriterProcess()){
>>>>> + WalStats.m_wal_write_walwriter++;
>>>>> + }
>>>>> + else
>>>>> + {
>>>>> + WalStats.m_wal_write_backend++;
>>>>> + }
>>>>>
>>>>> I think that it's better not to separate m_wal_write_xxx into two
>>>>> for
>>>>> walwriter and other processes. Instead, we can use one
>>>>> m_wal_write_xxx
>>>>> counter and make pgstat_send_wal() send also the process type to
>>>>> the stats collector. Then the stats collector can accumulate the
>>>>> counters
>>>>> per process type if necessary. If we adopt this approach, we can
>>>>> easily
>>>>> extend pg_stat_wal so that any fields can be reported per process
>>>>> type.
>>>>
>>>> I'll remove the above source code because these counters are not
>>>> useful.
>>>>
>>>>
>>>> On 2020-10-30 12:00, Fujii Masao wrote:
>>>>> On 2020/10/20 11:31, Masahiro Ikeda wrote:
>>>>>> Hi,
>>>>>>
>>>>>> I think we need to add some statistics to pg_stat_wal view.
>>>>>>
>>>>>> Although there are some parameter related WAL,
>>>>>> there are few statistics for tuning them.
>>>>>>
>>>>>> I think it's better to provide the following statistics.
>>>>>> Please let me know your comments.
>>>>>>
>>>>>> ```
>>>>>> postgres=# SELECT * from pg_stat_wal;
>>>>>> -[ RECORD 1 ]-------+------------------------------
>>>>>> wal_records | 2000224
>>>>>> wal_fpi | 47
>>>>>> wal_bytes | 248216337
>>>>>> wal_buffers_full | 20954
>>>>>> wal_init_file | 8
>>>>>> wal_write_backend | 20960
>>>>>> wal_write_walwriter | 46
>>>>>> wal_write_time | 51
>>>>>> wal_sync_backend | 7
>>>>>> wal_sync_walwriter | 8
>>>>>> wal_sync_time | 0
>>>>>> stats_reset | 2020-10-20 11:04:51.307771+09
>>>>>> ```
>>>>>>
>>>>>> 1. Basic statistics of WAL activity
>>>>>>
>>>>>> - wal_records: Total number of WAL records generated
>>>>>> - wal_fpi: Total number of WAL full page images generated
>>>>>> - wal_bytes: Total amount of WAL bytes generated
>>>>>>
>>>>>> To understand DB's performance, first, we will check the
>>>>>> performance
>>>>>> trends for the entire database instance.
>>>>>> For example, if the number of wal_fpi becomes higher, users may
>>>>>> tune
>>>>>> "wal_compression", "checkpoint_timeout" and so on.
>>>>>>
>>>>>> Although users can check the above statistics via EXPLAIN,
>>>>>> auto_explain,
>>>>>> autovacuum and pg_stat_statements now,
>>>>>> if users want to see the performance trends for the entire
>>>>>> database,
>>>>>> they must recalculate the statistics.
>>>>>>
>>>>>> I think it is useful to add the sum of the basic statistics.
>>>>>>
>>>>>>
>>>>>> 2. WAL segment file creation
>>>>>>
>>>>>> - wal_init_file: Total number of WAL segment files created.
>>>>>>
>>>>>> To create a new WAL file may have an impact on the performance of
>>>>>> a write-heavy workload generating lots of WAL. If this number is
>>>>>> reported high,
>>>>>> to reduce the number of this initialization, we can tune
>>>>>> WAL-related parameters
>>>>>> so that more "recycled" WAL files can be held.
>>>>>>
>>>>>>
>>>>>>
>>>>>> 3. Number of when WAL is flushed
>>>>>>
>>>>>> - wal_write_backend : Total number of WAL data written to the disk
>>>>>> by backends
>>>>>> - wal_write_walwriter : Total number of WAL data written to the
>>>>>> disk by walwriter
>>>>>> - wal_sync_backend : Total number of WAL data synced to the disk
>>>>>> by backends
>>>>>> - wal_sync_walwriter : Total number of WAL data synced to the disk
>>>>>> by walwrite
>>>>>>
>>>>>> I think it's useful for tuning "synchronous_commit" and
>>>>>> "commit_delay" for query executions.
>>>>>> If the number of WAL is flushed is high, users can know
>>>>>> "synchronous_commit" is useful for the workload.
>>>>>
>>>>> I just wonder how useful these counters are. Even without these
>>>>> counters,
>>>>> we already know synchronous_commit=off is likely to cause the
>>>>> better
>>>>> performance (but has the risk of data loss). So ISTM that these
>>>>> counters are
>>>>> not so useful when tuning synchronous_commit.
>>>>
>>>> Thanks, my understanding was wrong.
>>>> I agreed that your comments.
>>>>
>>>> I merged the statistics of *_backend and *_walwriter.
>>>> I think the sum of them is useful to calculate the average per
>>>> write/sync time.
>>>> For example, per write time is equals wal_write_time / wal_write.
>>>
>>> Understood.
>>>
>>> Thanks for updating the patch!
>>
>> Thanks for your comments.
>>
>>> patching file src/include/catalog/pg_proc.dat
>>> Hunk #1 FAILED at 5491.
>>> 1 out of 1 hunk FAILED -- saving rejects to file
>>> src/include/catalog/pg_proc.dat.rej
>>>
>>> I got this failure when applying the patch. Could you update the
>>> patch?
>>
>> Thanks, I updated the patch.
>>
>>> - Number of times WAL data was written to the disk because WAL
>>> buffers got full
>>> + Total number of times WAL data written to the disk because
>>> WAL
>>> buffers got full
>>>
>>> Isn't "was" necessary between "data" and "written"?
>>
>> Yes, I fixed it.
>>
>>> + <entry role="catalog_table_entry"><para
>>> role="column_definition">
>>> + <structfield>wal_bytes</structfield> <type>bigint</type>
>>>
>>> Shouldn't the type of wal_bytes be numeric because the total number
>>> of
>>> WAL bytes can exceed the range of bigint? I think that the type of
>>> pg_stat_statements.wal_bytes is also numeric for the same reason.
>>
>> Thanks, I fixed it.
>>
>> Since I cast the type of wal_bytes from PgStat_Counter to uint64,
>> I changed the type of PgStat_MsgWal and PgStat_WalStats too.
>>
>>> + <entry role="catalog_table_entry"><para
>>> role="column_definition">
>>> + <structfield>wal_write_time</structfield> <type>bigint</type>
>>>
>>> Shouldn't the type of wal_xxx_time be double precision,
>>> like pg_stat_database.blk_write_time?
>>
>> Thanks, I changed it.
>>
>>> Even when fsync is set to off or wal_sync_method is set to open_sync,
>>> wal_sync is incremented. Isn't this behavior confusing?
>
> What do you think about this comment?
Sorry, I'll change to increment wal_sync and wal_sync_time only
if a specific fsync method is called.
> I found that we discussed track-WAL-IO-timing feature at the past
> discussion
> about the similar feature [1]. But the feature was droppped from the
> proposal
> patch because there was the performance concern. So probably we need to
> revisit the past discussion and benchmark the performance. Thought?
>
> If track-WAL-IO-timing feature may cause performance regression,
> it might be an idea to extract wal_records, wal_fpi and wal_bytes parts
> from the patch and commit it at first.
>
> [1]
> https://postgr.es/m/CAJrrPGc6APFUGYNcPe4qcNxpL8gXKYv1KST+vwJcFtCSCEySnA@mail.gmail.com
Thanks, I'll check the thread.
I agree to add basic statistics at first and I attached the patch.
>>>
>>>
>>> + Total amount of time that has been spent in the portion of
>>> + WAL data was written to disk by backend and walwriter, in
>>> milliseconds
>>> + (if <xref linkend="guc-track-io-timing"/> is enabled,
>>> otherwise zero)
>>>
>>> With the patch, track_io_timing controls both IO for data files and
>>> WAL files. But we may want to track only either of them. So it's
>>> better
>>> to extend track_io_timing so that we can specify the tracking target
>>> in the parameter? For example, we can make track_io_timing accept
>>> data, wal and all. Or we should introduce new GUC for WAL, e.g.,
>>> track_wal_io_timing? Thought?
>>
>> OK, I introduced the new GUC "track_wal_io_timing".
>>
>>> I'm afraid that "by backend and walwriter" part can make us thinkg
>>> incorrectly that WAL writes by other processes like autovacuum
>>> are not tracked.
>>
>> Sorry, I removed "by backend and walwriter".
>
> Thanks for updating the patch!
>
> +WalUsage prevWalUsage;
>
> ISTM that we can declare this as static variable because
> it's used only in pgstat.c.
Thanks, I fixed it.
> + memset(&walusage, 0, sizeof(WalUsage));
> + WalUsageAccumDiff(&walusage, &pgWalUsage, &prevWalUsage);
>
> This memset seems unnecessary.
I couldn't understand why this memset is unnecessary.
Since WalUsageAccumDiff not only calculates the difference but also adds
the value,
I thought walusage needs to be initialized.
> /* We assume this initializes to zeroes */
> static const PgStat_MsgWal all_zeroes;
>
> This declaration of the variable should be placed around
> the top of pgstat_send_wal().
Sorry, I fixed it.
Regards,
--
Masahiro Ikeda
NTT DATA CORPORATION
Attachments:0001_add_basic_statistics_to_pg_stat_wal_view (text/x-diff, 8.7K) downloaddiff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgmlindex 98e1995453..6e661d6fae 100644--- a/doc/src/sgml/monitoring.sgml+++ b/doc/src/sgml/monitoring.sgml@@ -3447,6 +3447,33 @@ SELECT pid, wait_event_type, wait_event FROM pg_stat_activity WHERE wait_event i
</thead>
<tbody>
+ <row>+ <entry role="catalog_table_entry"><para role="column_definition">+ <structfield>wal_records</structfield> <type>bigint</type>+ </para>+ <para>+ Total number of WAL records generated+ </para></entry>+ </row>++ <row>+ <entry role="catalog_table_entry"><para role="column_definition">+ <structfield>wal_fpi</structfield> <type>bigint</type>+ </para>+ <para>+ Total number of WAL full page images generated+ </para></entry>+ </row>++ <row>+ <entry role="catalog_table_entry"><para role="column_definition">+ <structfield>wal_bytes</structfield> <type>numeric</type>+ </para>+ <para>+ Total amount of WAL bytes generated+ </para></entry>+ </row>+
<row>
<entry role="catalog_table_entry"><para role="column_definition">
<structfield>wal_buffers_full</structfield> <type>bigint</type>
diff --git a/src/backend/catalog/system_views.sql b/src/backend/catalog/system_views.sqlindex 2e4aa1c4b6..b140c210bc 100644--- a/src/backend/catalog/system_views.sql+++ b/src/backend/catalog/system_views.sql@@ -993,6 +993,9 @@ CREATE VIEW pg_stat_bgwriter AS
CREATE VIEW pg_stat_wal AS
SELECT
+ w.wal_records,+ w.wal_fpi,+ w.wal_bytes,
w.wal_buffers_full,
w.stats_reset
FROM pg_stat_get_wal() w;
diff --git a/src/backend/postmaster/pgstat.c b/src/backend/postmaster/pgstat.cindex e76e627c6b..781f2a5248 100644--- a/src/backend/postmaster/pgstat.c+++ b/src/backend/postmaster/pgstat.c@@ -41,6 +41,7 @@
#include "catalog/pg_database.h"
#include "catalog/pg_proc.h"
#include "common/ip.h"
+#include "executor/instrument.h"
#include "libpq/libpq.h"
#include "libpq/pqsignal.h"
#include "mb/pg_wchar.h"
@@ -142,6 +143,7 @@ char *pgstat_stat_tmpname = NULL;
*/
PgStat_MsgBgWriter BgWriterStats;
PgStat_MsgWal WalStats;
+static WalUsage prevWalUsage;
/*
* List of SLRU names that we keep stats for. There is no central registry of
@@ -3048,6 +3050,9 @@ pgstat_initialize(void)
MyBEEntry = &BackendStatusArray[MaxBackends + MyAuxProcType];
}
+ /* Initialize WAL usage status information */+ prevWalUsage = pgWalUsage;+
/* Set up a process-exit hook to clean up */
on_shmem_exit(pgstat_beshutdown_hook, 0);
}
@@ -4577,6 +4582,15 @@ pgstat_send_wal(void)
/* We assume this initializes to zeroes */
static const PgStat_MsgWal all_zeroes;
+ /* fill in some values using pgWalUsage */+ WalUsage walusage;+ memset(&walusage, 0, sizeof(WalUsage));+ WalUsageAccumDiff(&walusage, &pgWalUsage, &prevWalUsage);++ WalStats.m_wal_bytes = walusage.wal_bytes;+ WalStats.m_wal_records = walusage.wal_records;+ WalStats.m_wal_fpi = walusage.wal_fpi;+
/*
* This function can be called even if nothing at all has happened. In
* this case, avoid sending a completely empty message to the stats
@@ -4591,6 +4605,9 @@ pgstat_send_wal(void)
pgstat_setheader(&WalStats.m_hdr, PGSTAT_MTYPE_WAL);
pgstat_send(&WalStats, sizeof(WalStats));
+ /* remember the current numbers */+ prevWalUsage = pgWalUsage;+
/*
* Clear out the statistics buffer, so it can be re-used.
*/
@@ -6759,6 +6776,9 @@ pgstat_recv_bgwriter(PgStat_MsgBgWriter *msg, int len)
static void
pgstat_recv_wal(PgStat_MsgWal *msg, int len)
{
+ walStats.wal_records += msg->m_wal_records;+ walStats.wal_fpi += msg->m_wal_fpi;+ walStats.wal_bytes += msg->m_wal_bytes;
walStats.wal_buffers_full += msg->m_wal_buffers_full;
}
diff --git a/src/backend/postmaster/walwriter.c b/src/backend/postmaster/walwriter.cindex a52832fe90..ce9f4b7cf7 100644--- a/src/backend/postmaster/walwriter.c+++ b/src/backend/postmaster/walwriter.c@@ -253,6 +253,9 @@ WalWriterMain(void)
else if (left_till_hibernate > 0)
left_till_hibernate--;
+ /* Send WAL statistics */+ pgstat_send_wal();+
/*
* Sleep until we are signaled or WalWriterDelay has elapsed. If we
* haven't done anything useful for quite some time, lengthen the
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.cindex a210fc93b4..6afe1b6f56 100644--- a/src/backend/utils/adt/pgstatfuncs.c+++ b/src/backend/utils/adt/pgstatfuncs.c@@ -1703,10 +1703,11 @@ pg_stat_get_buf_alloc(PG_FUNCTION_ARGS)
Datum
pg_stat_get_wal(PG_FUNCTION_ARGS)
{
-#define PG_STAT_GET_WAL_COLS 2+#define PG_STAT_GET_WAL_COLS 5
TupleDesc tupdesc;
Datum values[PG_STAT_GET_WAL_COLS];
bool nulls[PG_STAT_GET_WAL_COLS];
+ char buf[256];
PgStat_WalStats *wal_stats;
/* Initialise values and NULL flags arrays */
@@ -1715,9 +1716,15 @@ pg_stat_get_wal(PG_FUNCTION_ARGS)
/* Initialise attributes information in the tuple descriptor */
tupdesc = CreateTemplateTupleDesc(PG_STAT_GET_WAL_COLS);
- TupleDescInitEntry(tupdesc, (AttrNumber) 1, "wal_buffers_full",+ TupleDescInitEntry(tupdesc, (AttrNumber) 1, "wal_records",
INT8OID, -1, 0);
- TupleDescInitEntry(tupdesc, (AttrNumber) 2, "stats_reset",+ TupleDescInitEntry(tupdesc, (AttrNumber) 2, "wal_fpi",+ INT8OID, -1, 0);+ TupleDescInitEntry(tupdesc, (AttrNumber) 3, "wal_bytes",+ NUMERICOID, -1, 0);+ TupleDescInitEntry(tupdesc, (AttrNumber) 4, "wal_buffers_full",+ INT8OID, -1, 0);+ TupleDescInitEntry(tupdesc, (AttrNumber) 5, "stats_reset",
TIMESTAMPTZOID, -1, 0);
BlessTupleDesc(tupdesc);
@@ -1726,8 +1733,18 @@ pg_stat_get_wal(PG_FUNCTION_ARGS)
wal_stats = pgstat_fetch_stat_wal();
/* Fill values and NULLs */
- values[0] = Int64GetDatum(wal_stats->wal_buffers_full);- values[1] = TimestampTzGetDatum(wal_stats->stat_reset_timestamp);+ values[0] = Int64GetDatum(wal_stats->wal_records);+ values[1] = Int64GetDatum(wal_stats->wal_fpi);++ /* Convert to numeric. */+ snprintf(buf, sizeof buf, UINT64_FORMAT, wal_stats->wal_bytes);+ values[2] = DirectFunctionCall3(numeric_in,+ CStringGetDatum(buf),+ ObjectIdGetDatum(0),+ Int32GetDatum(-1));++ values[3] = Int64GetDatum(wal_stats->wal_buffers_full);+ values[4] = TimestampTzGetDatum(wal_stats->stat_reset_timestamp);
/* Returns the record as Datum */
PG_RETURN_DATUM(HeapTupleGetDatum(heap_form_tuple(tupdesc, values, nulls)));
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.datindex c01da4bf01..67ab861260 100644--- a/src/include/catalog/pg_proc.dat+++ b/src/include/catalog/pg_proc.dat@@ -5503,8 +5503,9 @@
{ oid => '1136', descr => 'statistics: information about WAL activity',
proname => 'pg_stat_get_wal', proisstrict => 'f', provolatile => 's',
proparallel => 'r', prorettype => 'record', proargtypes => '',
- proallargtypes => '{int8,timestamptz}', proargmodes => '{o,o}',- proargnames => '{wal_buffers_full,stats_reset}',+ proallargtypes => '{int8,int8,numeric,int8,timestamptz}',+ proargmodes => '{o,o,o,o,o}',+ proargnames => '{wal_records,wal_fpi,wal_bytes,wal_buffers_full,stats_reset}',
prosrc => 'pg_stat_get_wal' },
{ oid => '2306', descr => 'statistics: information about SLRU caches',
diff --git a/src/include/pgstat.h b/src/include/pgstat.hindex 257e515bfe..cee3d28a2d 100644--- a/src/include/pgstat.h+++ b/src/include/pgstat.h@@ -459,6 +459,9 @@ typedef struct PgStat_MsgBgWriter
typedef struct PgStat_MsgWal
{
PgStat_MsgHdr m_hdr;
+ PgStat_Counter m_wal_records;+ PgStat_Counter m_wal_fpi;+ uint64 m_wal_bytes;
PgStat_Counter m_wal_buffers_full;
} PgStat_MsgWal;
@@ -798,6 +801,9 @@ typedef struct PgStat_GlobalStats
*/
typedef struct PgStat_WalStats
{
+ PgStat_Counter wal_records;+ PgStat_Counter wal_fpi;+ uint64 wal_bytes;
PgStat_Counter wal_buffers_full;
TimestampTz stat_reset_timestamp;
} PgStat_WalStats;
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.outindex 097ff5d111..6293ab57bc 100644--- a/src/test/regress/expected/rules.out+++ b/src/test/regress/expected/rules.out@@ -2138,9 +2138,12 @@ pg_stat_user_tables| SELECT pg_stat_all_tables.relid,
pg_stat_all_tables.autoanalyze_count
FROM pg_stat_all_tables
WHERE ((pg_stat_all_tables.schemaname <> ALL (ARRAY['pg_catalog'::name, 'information_schema'::name])) AND (pg_stat_all_tables.schemaname !~ '^pg_toast'::text));
-pg_stat_wal| SELECT w.wal_buffers_full,+pg_stat_wal| SELECT w.wal_records,+ w.wal_fpi,+ w.wal_bytes,+ w.wal_buffers_full,
w.stats_reset
- FROM pg_stat_get_wal() w(wal_buffers_full, stats_reset);+ FROM pg_stat_get_wal() w(wal_records, wal_fpi, wal_bytes, wal_buffers_full, stats_reset);
pg_stat_wal_receiver| SELECT s.pid,
s.status,
s.receive_start_lsn,
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To: pgsql-hackers@postgresql.org
Cc: ikedamsh@oss.nttdata.com, masao.fujii@oss.nttdata.com
Subject: Re: Add statistics to pg_stat_wal view for wal related parameter tuning
In-Reply-To: <89de5056627ebdd144967959bd789bd6@oss.nttdata.com>
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