On Sat, Apr 3, 2021 at 11:07 PM vignesh C <vignes...@gmail.com> wrote:
>
> On Fri, Apr 2, 2021 at 9:29 AM Masahiko Sawada <sawada.m...@gmail.com> wrote:
> >
> > On Fri, Apr 2, 2021 at 1:55 AM vignesh C <vignes...@gmail.com> wrote:
> > >
> > > On Thu, Apr 1, 2021 at 5:58 PM Amit Kapila <amit.kapil...@gmail.com>
> > > wrote:
> > > >
> > > > On Thu, Apr 1, 2021 at 3:43 PM vignesh C <vignes...@gmail.com> wrote:
> > > > >
> > > > > On Wed, Mar 31, 2021 at 11:32 AM vignesh C <vignes...@gmail.com>
> > > > > wrote:
> > > > > >
> > > > > > On Tue, Mar 30, 2021 at 11:00 AM Andres Freund <and...@anarazel.de>
> > > > > > wrote:
> > > > > > >
> > > > > > > Hi,
> > > > > > >
> > > > > > > On 2021-03-30 10:13:29 +0530, vignesh C wrote:
> > > > > > > > On Tue, Mar 30, 2021 at 6:28 AM Andres Freund
> > > > > > > > <and...@anarazel.de> wrote:
> > > > > > > > > Any chance you could write a tap test exercising a few of
> > > > > > > > > these cases?
> > > > > > > >
> > > > > > > > I can try to write a patch for this if nobody objects.
> > > > > > >
> > > > > > > Cool!
> > > > > > >
> > > > > >
> > > > > > Attached a patch which has the test for the first scenario.
> > > > > >
> > > > > > > > > E.g. things like:
> > > > > > > > >
> > > > > > > > > - create a few slots, drop one of them, shut down, start up,
> > > > > > > > > verify
> > > > > > > > > stats are still sane
> > > > > > > > > - create a few slots, shut down, manually remove a slot, lower
> > > > > > > > > max_replication_slots, start up
> > > > > > > >
> > > > > > > > Here by "manually remove a slot", do you mean to remove the slot
> > > > > > > > manually from the pg_replslot folder?
> > > > > > >
> > > > > > > Yep - thereby allowing max_replication_slots after the
> > > > > > > shutdown/start to
> > > > > > > be lower than the number of slots-stats objects.
> > > > > >
> > > > > > I have not included the 2nd test in the patch as the test fails with
> > > > > > following warnings and also displays the statistics of the removed
> > > > > > slot:
> > > > > > WARNING: problem in alloc set Statistics snapshot: detected write
> > > > > > past chunk end in block 0x55d038b8e410, chunk 0x55d038b8e438
> > > > > > WARNING: problem in alloc set Statistics snapshot: detected write
> > > > > > past chunk end in block 0x55d038b8e410, chunk 0x55d038b8e438
> > > > > >
> > > > > > This happens because the statistics file has an additional slot
> > > > > > present even though the replication slot was removed. I felt this
> > > > > > issue should be fixed. I will try to fix this issue and send the
> > > > > > second test along with the fix.
> > > > >
> > > > > I felt from the statistics collector process, there is no way in which
> > > > > we can identify if the replication slot is present or not because the
> > > > > statistic collector process does not have access to shared memory.
> > > > > Anything that the statistic collector process does independently by
> > > > > traversing and removing the statistics of the replication slot
> > > > > exceeding the max_replication_slot has its drawback of removing some
> > > > > valid replication slot's statistics data.
> > > > > Any thoughts on how we can identify the replication slot which has
> > > > > been dropped?
> > > > > Can someone point me to the shared stats patch link with which message
> > > > > loss can be avoided. I wanted to see a scenario where something like
> > > > > the slot is dropped but the statistics are not updated because of an
> > > > > immediate shutdown or server going down abruptly can occur or not with
> > > > > the shared stats patch.
> > > > >
> > > >
> > > > I don't think it is easy to simulate a scenario where the 'drop'
> > > > message is dropped and I think that is why the test contains the step
> > > > to manually remove the slot. At this stage, you can probably provide a
> > > > test patch and a code-fix patch where it just drops the extra slots
> > > > from the stats file. That will allow us to test it with a shared
> > > > memory stats patch on which Andres and Horiguchi-San are working. If
> > > > we still continue to pursue with current approach then as Andres
> > > > suggested we might send additional information from
> > > > RestoreSlotFromDisk to keep it in sync.
> > >
> > > Thanks for your comments, Attached patch has the fix for the same.
> > > Also attached a couple of more patches which addresses the comments
> > > which Andres had listed i.e changing char to NameData type and also to
> > > display the unspilled/unstreamed transaction information in the
> > > replication statistics.
> > > Thoughts?
> >
> > Thank you for the patches!
> >
> > I've looked at those patches and here are some comments on 0001, 0002,
> > and 0003 patch:
>
> Thanks for the comments.
>
> > 0001 patch:
> >
> > - values[0] = PointerGetDatum(cstring_to_text(s->slotname));
> > + values[0] = PointerGetDatum(cstring_to_text(s->slotname.data));
> >
> > We can use NameGetDatum() instead.
>
> I felt we will not be able to use NameGetDatum because this function
> will not have access to the value throughout the loop and NameGetDatum
> must ensure the pointed-to value has adequate lifetime.
>
> > ---
> > 0002 patch:
> >
> > The patch uses logical replication to test replication slots
> > statistics but I think it's necessarily necessary. It would be more
> > simple to use logical decoding. Maybe we can add TAP tests to
> > contrib/test_decoding.
> >
>
> I will try to change it to test_decoding if feasible and post in the
> next version.
>
I have modified the patch to include tap tests in contrib/test_decoding.
Attached v3 patch has the changes for the same.
Thoughts?
Regards,
Vignesh
From ac894e550f624f21f1ac08cc48d1dbad767e9a5b Mon Sep 17 00:00:00 2001
From: vignesh <vignesh21@gmail.com>
Date: Mon, 5 Apr 2021 19:01:03 +0530
Subject: [PATCH v3 1/3] Added total txns and total txn bytes to replication
statistics.
This adds the statistics about total transactions count and total transaction
data logically replicated to the decoding output plugin from ReorderBuffer.
Users can query the pg_stat_replication_slots view to check these stats.
This also includes changing char datatype to NameData datatype for slotname.
---
doc/src/sgml/monitoring.sgml | 24 ++++++++++++
src/backend/catalog/system_views.sql | 2 +
src/backend/postmaster/pgstat.c | 38 ++++++++++---------
src/backend/replication/logical/logical.c | 30 ++++++++++-----
.../replication/logical/reorderbuffer.c | 5 +++
src/backend/replication/slot.c | 7 +++-
src/backend/utils/adt/pgstatfuncs.c | 10 +++--
src/include/catalog/pg_proc.dat | 6 +--
src/include/pgstat.h | 15 ++++----
src/include/replication/reorderbuffer.h | 4 ++
src/test/regress/expected/rules.out | 4 +-
11 files changed, 103 insertions(+), 42 deletions(-)
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index 56018745c8..25975d2228 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -2689,6 +2689,30 @@ SELECT pid, wait_event_type, wait_event FROM pg_stat_activity WHERE wait_event i
</entry>
</row>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>total_txns</structfield> <type>bigint</type>
+ </para>
+ <para>
+ Number of decoded transactions sent to the decoding output plugin for
+ this slot. This counter is used to maintain the top level transactions,
+ so the counter is not incremented for subtransactions.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>total_bytes</structfield><type>bigint</type>
+ </para>
+ <para>
+ Amount of decoded transactions data sent to the decoding output plugin
+ while decoding the changes from WAL for this slot. This and total_txns
+ for this slot can be used to gauge the total amount of data during
+ logical decoding.
+ </para>
+ </entry>
+ </row>
+
<row>
<entry role="catalog_table_entry"><para role="column_definition">
<structfield>stats_reset</structfield> <type>timestamp with time zone</type>
diff --git a/src/backend/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index 5f2541d316..e3991eb6f6 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -874,6 +874,8 @@ CREATE VIEW pg_stat_replication_slots AS
s.stream_txns,
s.stream_count,
s.stream_bytes,
+ s.total_txns,
+ s.total_bytes,
s.stats_reset
FROM pg_stat_get_replication_slots() AS s;
diff --git a/src/backend/postmaster/pgstat.c b/src/backend/postmaster/pgstat.c
index 4c4b072068..1d8626d17c 100644
--- a/src/backend/postmaster/pgstat.c
+++ b/src/backend/postmaster/pgstat.c
@@ -62,6 +62,7 @@
#include "storage/pg_shmem.h"
#include "storage/proc.h"
#include "storage/procsignal.h"
+#include "utils/builtins.h"
#include "utils/guc.h"
#include "utils/memutils.h"
#include "utils/ps_status.h"
@@ -1525,7 +1526,7 @@ pgstat_reset_replslot_counter(const char *name)
if (SlotIsPhysical(slot))
return;
- strlcpy(msg.m_slotname, name, NAMEDATALEN);
+ namestrcpy(&msg.m_slotname, name);
msg.clearall = false;
}
else
@@ -1743,10 +1744,7 @@ pgstat_report_tempfile(size_t filesize)
* ----------
*/
void
-pgstat_report_replslot(const char *slotname, PgStat_Counter spilltxns,
- PgStat_Counter spillcount, PgStat_Counter spillbytes,
- PgStat_Counter streamtxns, PgStat_Counter streamcount,
- PgStat_Counter streambytes)
+pgstat_report_replslot(const PgStat_ReplSlotStats *repSlotStat)
{
PgStat_MsgReplSlot msg;
@@ -1754,14 +1752,16 @@ pgstat_report_replslot(const char *slotname, PgStat_Counter spilltxns,
* Prepare and send the message
*/
pgstat_setheader(&msg.m_hdr, PGSTAT_MTYPE_REPLSLOT);
- strlcpy(msg.m_slotname, slotname, NAMEDATALEN);
+ namestrcpy(&msg.m_slotname, NameStr(repSlotStat->slotname));
msg.m_drop = false;
- msg.m_spill_txns = spilltxns;
- msg.m_spill_count = spillcount;
- msg.m_spill_bytes = spillbytes;
- msg.m_stream_txns = streamtxns;
- msg.m_stream_count = streamcount;
- msg.m_stream_bytes = streambytes;
+ msg.m_spill_txns = repSlotStat->spill_txns;
+ msg.m_spill_count = repSlotStat->spill_count;;
+ msg.m_spill_bytes = repSlotStat->spill_bytes;
+ msg.m_stream_txns = repSlotStat->stream_txns;
+ msg.m_stream_count = repSlotStat->stream_count;
+ msg.m_stream_bytes = repSlotStat->stream_bytes;
+ msg.m_total_txns = repSlotStat->total_txns;
+ msg.m_total_bytes = repSlotStat->total_bytes;
pgstat_send(&msg, sizeof(PgStat_MsgReplSlot));
}
@@ -1777,7 +1777,7 @@ pgstat_report_replslot_drop(const char *slotname)
PgStat_MsgReplSlot msg;
pgstat_setheader(&msg.m_hdr, PGSTAT_MTYPE_REPLSLOT);
- strlcpy(msg.m_slotname, slotname, NAMEDATALEN);
+ namestrcpy(&msg.m_slotname, slotname);
msg.m_drop = true;
pgstat_send(&msg, sizeof(PgStat_MsgReplSlot));
}
@@ -5049,7 +5049,7 @@ pgstat_recv_resetreplslotcounter(PgStat_MsgResetreplslotcounter *msg,
else
{
/* Get the index of replication slot statistics to reset */
- idx = pgstat_replslot_index(msg->m_slotname, false);
+ idx = pgstat_replslot_index(NameStr(msg->m_slotname), false);
/*
* Nothing to do if the given slot entry is not found. This could
@@ -5347,7 +5347,7 @@ pgstat_recv_replslot(PgStat_MsgReplSlot *msg, int len)
* Get the index of replication slot statistics. On dropping, we don't
* create the new statistics.
*/
- idx = pgstat_replslot_index(msg->m_slotname, !msg->m_drop);
+ idx = pgstat_replslot_index(NameStr(msg->m_slotname), !msg->m_drop);
/*
* The slot entry is not found or there is no space to accommodate the new
@@ -5379,6 +5379,8 @@ pgstat_recv_replslot(PgStat_MsgReplSlot *msg, int len)
replSlotStats[idx].stream_txns += msg->m_stream_txns;
replSlotStats[idx].stream_count += msg->m_stream_count;
replSlotStats[idx].stream_bytes += msg->m_stream_bytes;
+ replSlotStats[idx].total_txns += msg->m_total_txns;
+ replSlotStats[idx].total_bytes += msg->m_total_bytes;
}
}
@@ -5572,7 +5574,7 @@ pgstat_replslot_index(const char *name, bool create_it)
Assert(nReplSlotStats <= max_replication_slots);
for (i = 0; i < nReplSlotStats; i++)
{
- if (strcmp(replSlotStats[i].slotname, name) == 0)
+ if (namestrcmp(&replSlotStats[i].slotname, name) == 0)
return i; /* found */
}
@@ -5585,7 +5587,7 @@ pgstat_replslot_index(const char *name, bool create_it)
/* Register new slot */
memset(&replSlotStats[nReplSlotStats], 0, sizeof(PgStat_ReplSlotStats));
- strlcpy(replSlotStats[nReplSlotStats].slotname, name, NAMEDATALEN);
+ namestrcpy(&replSlotStats[nReplSlotStats].slotname, name);
return nReplSlotStats++;
}
@@ -5606,6 +5608,8 @@ pgstat_reset_replslot(int i, TimestampTz ts)
replSlotStats[i].stream_txns = 0;
replSlotStats[i].stream_count = 0;
replSlotStats[i].stream_bytes = 0;
+ replSlotStats[i].total_txns = 0;
+ replSlotStats[i].total_bytes = 0;
replSlotStats[i].stat_reset_timestamp = ts;
}
diff --git a/src/backend/replication/logical/logical.c b/src/backend/replication/logical/logical.c
index 2f6803637b..d0ad694477 100644
--- a/src/backend/replication/logical/logical.c
+++ b/src/backend/replication/logical/logical.c
@@ -1763,30 +1763,42 @@ void
UpdateDecodingStats(LogicalDecodingContext *ctx)
{
ReorderBuffer *rb = ctx->reorder;
+ PgStat_ReplSlotStats repSlotStat;
/*
- * Nothing to do if we haven't spilled or streamed anything since the last
- * time the stats has been sent.
+ * Nothing to do if we don't have any replication stats to be sent.
*/
- if (rb->spillBytes <= 0 && rb->streamBytes <= 0)
+ if (rb->spillBytes <= 0 && rb->streamBytes <= 0 && rb->totalBytes <= 0)
return;
- elog(DEBUG2, "UpdateDecodingStats: updating stats %p %lld %lld %lld %lld %lld %lld",
+ elog(DEBUG2, "UpdateDecodingStats: updating stats %p %lld %lld %lld %lld %lld %lld %lld %lld",
rb,
(long long) rb->spillTxns,
(long long) rb->spillCount,
(long long) rb->spillBytes,
(long long) rb->streamTxns,
(long long) rb->streamCount,
- (long long) rb->streamBytes);
-
- pgstat_report_replslot(NameStr(ctx->slot->data.name),
- rb->spillTxns, rb->spillCount, rb->spillBytes,
- rb->streamTxns, rb->streamCount, rb->streamBytes);
+ (long long) rb->streamBytes,
+ (long long) rb->totalTxns,
+ (long long) rb->totalBytes);
+
+ namestrcpy(&repSlotStat.slotname, NameStr(ctx->slot->data.name));
+ repSlotStat.spill_txns = rb->spillTxns;
+ repSlotStat.spill_count = rb->spillCount;
+ repSlotStat.spill_bytes = rb->spillBytes;
+ repSlotStat.stream_txns = rb->streamTxns;
+ repSlotStat.stream_count = rb->streamCount;
+ repSlotStat.stream_bytes = rb->streamBytes;
+ repSlotStat.total_txns = rb->totalTxns;
+ repSlotStat.total_bytes = rb->totalBytes;
+
+ pgstat_report_replslot(&repSlotStat);
rb->spillTxns = 0;
rb->spillCount = 0;
rb->spillBytes = 0;
rb->streamTxns = 0;
rb->streamCount = 0;
rb->streamBytes = 0;
+ rb->totalTxns = 0;
+ rb->totalBytes = 0;
}
diff --git a/src/backend/replication/logical/reorderbuffer.c b/src/backend/replication/logical/reorderbuffer.c
index 52d06285a2..5bc0b05a0e 100644
--- a/src/backend/replication/logical/reorderbuffer.c
+++ b/src/backend/replication/logical/reorderbuffer.c
@@ -350,6 +350,8 @@ ReorderBufferAllocate(void)
buffer->streamTxns = 0;
buffer->streamCount = 0;
buffer->streamBytes = 0;
+ buffer->totalTxns = 0;
+ buffer->totalBytes = 0;
buffer->current_restart_decoding_lsn = InvalidXLogRecPtr;
@@ -659,6 +661,8 @@ ReorderBufferTXNByXid(ReorderBuffer *rb, TransactionId xid, bool create,
dlist_push_tail(&rb->toplevel_by_lsn, &txn->node);
AssertTXNLsnOrder(rb);
}
+
+ rb->totalTxns++;
}
else
txn = NULL; /* not found and not asked to create */
@@ -3078,6 +3082,7 @@ ReorderBufferChangeMemoryUpdate(ReorderBuffer *rb,
{
txn->size += sz;
rb->size += sz;
+ rb->totalBytes += sz;
/* Update the total size in the top transaction. */
if (toptxn)
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index 75a087c2f9..f61b163f78 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -328,7 +328,12 @@ ReplicationSlotCreate(const char *name, bool db_specific,
* ReplicationSlotAllocationLock.
*/
if (SlotIsLogical(slot))
- pgstat_report_replslot(NameStr(slot->data.name), 0, 0, 0, 0, 0, 0);
+ {
+ PgStat_ReplSlotStats repSlotStat;
+ MemSet(&repSlotStat, 0, sizeof(PgStat_ReplSlotStats));
+ namestrcpy(&repSlotStat.slotname, NameStr(slot->data.name));
+ pgstat_report_replslot(&repSlotStat);
+ }
/*
* Now that the slot has been marked as in_use and active, it's safe to
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index 9ffbca685c..54eb3d1538 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -2279,7 +2279,7 @@ pg_stat_get_archiver(PG_FUNCTION_ARGS)
Datum
pg_stat_get_replication_slots(PG_FUNCTION_ARGS)
{
-#define PG_STAT_GET_REPLICATION_SLOT_COLS 8
+#define PG_STAT_GET_REPLICATION_SLOT_COLS 10
ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
TupleDesc tupdesc;
Tuplestorestate *tupstore;
@@ -2323,18 +2323,20 @@ pg_stat_get_replication_slots(PG_FUNCTION_ARGS)
MemSet(values, 0, sizeof(values));
MemSet(nulls, 0, sizeof(nulls));
- values[0] = PointerGetDatum(cstring_to_text(s->slotname));
+ values[0] = CStringGetTextDatum(NameStr(s->slotname));
values[1] = Int64GetDatum(s->spill_txns);
values[2] = Int64GetDatum(s->spill_count);
values[3] = Int64GetDatum(s->spill_bytes);
values[4] = Int64GetDatum(s->stream_txns);
values[5] = Int64GetDatum(s->stream_count);
values[6] = Int64GetDatum(s->stream_bytes);
+ values[7] = Int64GetDatum(s->total_txns);
+ values[8] = Int64GetDatum(s->total_bytes);
if (s->stat_reset_timestamp == 0)
- nulls[7] = true;
+ nulls[9] = true;
else
- values[7] = TimestampTzGetDatum(s->stat_reset_timestamp);
+ values[9] = TimestampTzGetDatum(s->stat_reset_timestamp);
tuplestore_putvalues(tupstore, tupdesc, values, nulls);
}
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 69ffd0c3f4..8b2071c77b 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5296,9 +5296,9 @@
proname => 'pg_stat_get_replication_slots', prorows => '10',
proisstrict => 'f', proretset => 't', provolatile => 's', proparallel => 'r',
prorettype => 'record', proargtypes => '',
- proallargtypes => '{text,int8,int8,int8,int8,int8,int8,timestamptz}',
- proargmodes => '{o,o,o,o,o,o,o,o}',
- proargnames => '{slot_name,spill_txns,spill_count,spill_bytes,stream_txns,stream_count,stream_bytes,stats_reset}',
+ proallargtypes => '{text,int8,int8,int8,int8,int8,int8,int8,int8,timestamptz}',
+ proargmodes => '{o,o,o,o,o,o,o,o,o,o}',
+ proargnames => '{slot_name,spill_txns,spill_count,spill_bytes,stream_txns,stream_count,stream_bytes,total_txns,total_bytes,stats_reset}',
prosrc => 'pg_stat_get_replication_slots' },
{ oid => '6118', descr => 'statistics: information about subscription',
proname => 'pg_stat_get_subscription', prorows => '10', proisstrict => 'f',
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 7cd137506e..63b740ab40 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -378,7 +378,7 @@ typedef struct PgStat_MsgResetslrucounter
typedef struct PgStat_MsgResetreplslotcounter
{
PgStat_MsgHdr m_hdr;
- char m_slotname[NAMEDATALEN];
+ NameData m_slotname;
bool clearall;
} PgStat_MsgResetreplslotcounter;
@@ -506,7 +506,7 @@ typedef struct PgStat_MsgSLRU
typedef struct PgStat_MsgReplSlot
{
PgStat_MsgHdr m_hdr;
- char m_slotname[NAMEDATALEN];
+ NameData m_slotname;
bool m_drop;
PgStat_Counter m_spill_txns;
PgStat_Counter m_spill_count;
@@ -514,6 +514,8 @@ typedef struct PgStat_MsgReplSlot
PgStat_Counter m_stream_txns;
PgStat_Counter m_stream_count;
PgStat_Counter m_stream_bytes;
+ PgStat_Counter m_total_txns;
+ PgStat_Counter m_total_bytes;
} PgStat_MsgReplSlot;
@@ -871,13 +873,15 @@ typedef struct PgStat_SLRUStats
*/
typedef struct PgStat_ReplSlotStats
{
- char slotname[NAMEDATALEN];
+ NameData slotname;
PgStat_Counter spill_txns;
PgStat_Counter spill_count;
PgStat_Counter spill_bytes;
PgStat_Counter stream_txns;
PgStat_Counter stream_count;
PgStat_Counter stream_bytes;
+ PgStat_Counter total_txns;
+ PgStat_Counter total_bytes;
TimestampTz stat_reset_timestamp;
} PgStat_ReplSlotStats;
@@ -980,10 +984,7 @@ extern void pgstat_report_recovery_conflict(int reason);
extern void pgstat_report_deadlock(void);
extern void pgstat_report_checksum_failures_in_db(Oid dboid, int failurecount);
extern void pgstat_report_checksum_failure(void);
-extern void pgstat_report_replslot(const char *slotname, PgStat_Counter spilltxns,
- PgStat_Counter spillcount, PgStat_Counter spillbytes,
- PgStat_Counter streamtxns, PgStat_Counter streamcount,
- PgStat_Counter streambytes);
+extern void pgstat_report_replslot(const PgStat_ReplSlotStats *repSlotStat);
extern void pgstat_report_replslot_drop(const char *slotname);
extern void pgstat_initialize(void);
diff --git a/src/include/replication/reorderbuffer.h b/src/include/replication/reorderbuffer.h
index 565a961d6a..a372b70b7d 100644
--- a/src/include/replication/reorderbuffer.h
+++ b/src/include/replication/reorderbuffer.h
@@ -618,6 +618,10 @@ struct ReorderBuffer
int64 streamTxns; /* number of transactions streamed */
int64 streamCount; /* streaming invocation counter */
int64 streamBytes; /* amount of data streamed */
+
+ /* Statistics about all the replicated transactions */
+ int64 totalTxns; /* total number of transactions replicated */
+ int64 totalBytes; /* total amount of data replicated */
};
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 9b59a7b4a5..f0eea8b18f 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -2056,8 +2056,10 @@ pg_stat_replication_slots| SELECT s.slot_name,
s.stream_txns,
s.stream_count,
s.stream_bytes,
+ s.total_txns,
+ s.total_bytes,
s.stats_reset
- FROM pg_stat_get_replication_slots() s(slot_name, spill_txns, spill_count, spill_bytes, stream_txns, stream_count, stream_bytes, stats_reset);
+ FROM pg_stat_get_replication_slots() s(slot_name, spill_txns, spill_count, spill_bytes, stream_txns, stream_count, stream_bytes, total_txns, total_bytes, stats_reset);
pg_stat_slru| SELECT s.name,
s.blks_zeroed,
s.blks_hit,
--
2.25.1
From d4be3220eaba71b8c6916a85314c43682bea9a33 Mon Sep 17 00:00:00 2001
From: vignesh <vignesh21@gmail.com>
Date: Mon, 5 Apr 2021 18:17:21 +0530
Subject: [PATCH v3 2/3] Added tests for verification of logical replication
statistics.
Added tests for verification of logical replication statistics after
restart of server.
---
contrib/test_decoding/Makefile | 2 +
contrib/test_decoding/t/001_repl_stats.pl | 112 ++++++++++++++++++++++
2 files changed, 114 insertions(+)
create mode 100644 contrib/test_decoding/t/001_repl_stats.pl
diff --git a/contrib/test_decoding/Makefile b/contrib/test_decoding/Makefile
index c5e28ce5cc..9a31e0b879 100644
--- a/contrib/test_decoding/Makefile
+++ b/contrib/test_decoding/Makefile
@@ -17,6 +17,8 @@ ISOLATION_OPTS = --temp-config $(top_srcdir)/contrib/test_decoding/logical.conf
# typical installcheck users do not have (e.g. buildfarm clients).
NO_INSTALLCHECK = 1
+TAP_TESTS = 1
+
ifdef USE_PGXS
PG_CONFIG = pg_config
PGXS := $(shell $(PG_CONFIG) --pgxs)
diff --git a/contrib/test_decoding/t/001_repl_stats.pl b/contrib/test_decoding/t/001_repl_stats.pl
new file mode 100644
index 0000000000..4f50804bf4
--- /dev/null
+++ b/contrib/test_decoding/t/001_repl_stats.pl
@@ -0,0 +1,112 @@
+# Test replication statistics data in pg_stat_replication_slots is sane after
+# drop replication slot and restart.
+use strict;
+use warnings;
+use File::Path qw(rmtree);
+use PostgresNode;
+use TestLib;
+use Test::More tests => 2;
+
+# Test set-up
+my $node = get_new_node('test');
+$node->init(allows_streaming => 'logical');
+$node->append_conf('postgresql.conf', 'synchronous_commit = on');
+$node->start;
+
+$node->safe_psql('postgres', q(CREATE FUNCTION wait_for_decode_stats(check_reset bool, check_slot_name text) RETURNS void AS $$
+DECLARE
+ start_time timestamptz := clock_timestamp();
+ txn_count bool;
+BEGIN
+ -- we don't want to wait forever; loop will exit after 30 seconds
+ FOR i IN 1 .. 5 LOOP
+
+ -- check to see if all updates have been reset/updated
+ SELECT (total_txns > 0) INTO txn_count
+ FROM pg_stat_replication_slots WHERE slot_name=check_slot_name;
+
+ exit WHEN txn_count;
+
+ -- wait a little
+ perform pg_sleep_for('100 milliseconds');
+
+ -- reset stats snapshot so we can test again
+ perform pg_stat_clear_snapshot();
+
+ END LOOP;
+
+ -- report time waited in postmaster log (where it won't change test output)
+ RAISE LOG 'wait_for_decode_stats delayed % seconds',
+ extract(epoch from clock_timestamp() - start_time);
+END
+$$ LANGUAGE plpgsql;
+));
+
+# Create replication slots.
+$node->safe_psql('postgres',
+ "SELECT 'init' FROM pg_create_logical_replication_slot('regression_slot1', 'test_decoding')");
+$node->safe_psql('postgres',
+ "SELECT 'init' FROM pg_create_logical_replication_slot('regression_slot2', 'test_decoding')");
+$node->safe_psql('postgres',
+ "SELECT 'init' FROM pg_create_logical_replication_slot('regression_slot3', 'test_decoding')");
+$node->safe_psql('postgres',
+ "SELECT 'init' FROM pg_create_logical_replication_slot('regression_slot4', 'test_decoding')");
+
+# Create table.
+$node->safe_psql('postgres',
+ "CREATE TABLE test_repl_stat(col1 int)");
+$node->safe_psql('postgres',
+ "SELECT data FROM pg_logical_slot_get_changes('regression_slot1', NULL, NULL, 'include-xids', '0', 'skip-empty-xacts', '1')");
+$node->safe_psql('postgres',
+ "SELECT data FROM pg_logical_slot_get_changes('regression_slot2', NULL, NULL, 'include-xids', '0', 'skip-empty-xacts', '1')");
+$node->safe_psql('postgres',
+ "SELECT data FROM pg_logical_slot_get_changes('regression_slot3', NULL, NULL, 'include-xids', '0', 'skip-empty-xacts', '1')");
+$node->safe_psql('postgres',
+ "SELECT data FROM pg_logical_slot_get_changes('regression_slot4', NULL, NULL, 'include-xids', '0', 'skip-empty-xacts', '1')");
+
+# Insert some data.
+$node->safe_psql('postgres', "INSERT INTO test_repl_stat values(generate_series(1, 5));");
+
+# Wait for the statistics to be updated.
+$node->safe_psql('postgres', "SELECT wait_for_decode_stats(true, 'regression_slot1')");
+$node->safe_psql('postgres', "SELECT wait_for_decode_stats(true, 'regression_slot2')");
+$node->safe_psql('postgres', "SELECT wait_for_decode_stats(true, 'regression_slot3')");
+$node->safe_psql('postgres', "SELECT wait_for_decode_stats(true, 'regression_slot4')");
+
+# Test to verify replication statistics data is updated in
+# pg_stat_replication_slots statistics view.
+my $result = $node->safe_psql('postgres',
+ "SELECT slot_name, total_txns > 0 AS total_txn, total_bytes > 0 AS total_bytes
+ FROM pg_stat_replication_slots ORDER BY slot_name"
+);
+is($result, qq(regression_slot1|t|t
+regression_slot2|t|t
+regression_slot3|t|t
+regression_slot4|t|t), 'check replication statistics are updated');
+
+# Test to drop one of the subscribers and verify replication statistics data is
+# fine after publisher is restarted.
+$node->safe_psql('postgres', "SELECT pg_drop_replication_slot('regression_slot4')");
+
+$node->stop;
+$node->start;
+
+# Verify statistics data present in pg_stat_replication_slots are sane after
+# publisher is restarted
+$result = $node->safe_psql('postgres',
+ "SELECT slot_name, total_txns > 0 AS total_txn, total_bytes > 0 AS total_bytes
+ FROM pg_stat_replication_slots ORDER BY slot_name"
+);
+is($result, qq(regression_slot1|t|t
+regression_slot2|t|t
+regression_slot3|t|t), 'check replication statistics are updated');
+
+# cleanup
+$node->safe_psql('postgres', "DROP TABLE test_repl_stat");
+$node->safe_psql('postgres', "DROP FUNCTION wait_for_decode_stats");
+$node->safe_psql('postgres', "SELECT pg_drop_replication_slot('regression_slot1')");
+$node->safe_psql('postgres', "SELECT pg_drop_replication_slot('regression_slot2')");
+$node->safe_psql('postgres', "SELECT pg_drop_replication_slot('regression_slot3')");
+
+# shutdown
+$node->stop;
--
2.25.1
From 9c39345b701bf8794bb5ef8fa4f1de2c33f8700a Mon Sep 17 00:00:00 2001
From: vignesh <vignesh21@gmail.com>
Date: Mon, 5 Apr 2021 19:09:25 +0530
Subject: [PATCH v3 3/3] Handle overwriting of replication slot statistic
issue.
There is a remote scenario where one of the replication slots is dropped and
the drop slot statistics message is not received by the statistic collector
process, now if the max_replication_slots is reduced to the actual number of
replication slots that are in use and the publisher is re-started then the
statistics process will not be aware of this and the statistic collector
process will write beyond the slots available, fixed it by skipping the
replication slot statistic that are after max_replication_slot.
---
contrib/test_decoding/t/001_repl_stats.pl | 24 +++++++++++++++++++++--
src/backend/postmaster/pgstat.c | 20 +++++++++++++++++++
2 files changed, 42 insertions(+), 2 deletions(-)
diff --git a/contrib/test_decoding/t/001_repl_stats.pl b/contrib/test_decoding/t/001_repl_stats.pl
index 4f50804bf4..53283f55bd 100644
--- a/contrib/test_decoding/t/001_repl_stats.pl
+++ b/contrib/test_decoding/t/001_repl_stats.pl
@@ -5,7 +5,7 @@ use warnings;
use File::Path qw(rmtree);
use PostgresNode;
use TestLib;
-use Test::More tests => 2;
+use Test::More tests => 3;
# Test set-up
my $node = get_new_node('test');
@@ -101,12 +101,32 @@ is($result, qq(regression_slot1|t|t
regression_slot2|t|t
regression_slot3|t|t), 'check replication statistics are updated');
+# Test to remove one of the replication slots and adjust max_replication_slots
+# accordingly to the number of slots and verify replication statistics data is
+# fine after publisher is restarted.
+$node->stop;
+my $publisher_data = $node->data_dir;
+my $slot3_replslotdir = "$publisher_data/pg_replslot/regression_slot3";
+
+rmtree($slot3_replslotdir);
+
+$node->append_conf('postgresql.conf', 'max_replication_slots = 2');
+$node->start;
+
+# Verify statistics data present in pg_stat_replication_slots are sane after
+# publisher is restarted
+$result = $node->safe_psql('postgres',
+ "SELECT slot_name, total_txns > 0 AS total_txn, total_bytes > 0 AS total_bytes
+ FROM pg_stat_replication_slots ORDER BY slot_name"
+);
+is($result, qq(regression_slot1|t|t
+regression_slot2|t|t), 'check replication statistics are updated');
+
# cleanup
$node->safe_psql('postgres', "DROP TABLE test_repl_stat");
$node->safe_psql('postgres', "DROP FUNCTION wait_for_decode_stats");
$node->safe_psql('postgres', "SELECT pg_drop_replication_slot('regression_slot1')");
$node->safe_psql('postgres', "SELECT pg_drop_replication_slot('regression_slot2')");
-$node->safe_psql('postgres', "SELECT pg_drop_replication_slot('regression_slot3')");
# shutdown
$node->stop;
diff --git a/src/backend/postmaster/pgstat.c b/src/backend/postmaster/pgstat.c
index 1d8626d17c..ede97362b7 100644
--- a/src/backend/postmaster/pgstat.c
+++ b/src/backend/postmaster/pgstat.c
@@ -4078,6 +4078,26 @@ pgstat_read_statsfiles(Oid onlydb, bool permanent, bool deep)
memset(&replSlotStats[nReplSlotStats], 0, sizeof(PgStat_ReplSlotStats));
goto done;
}
+
+ /*
+ * There is a remote scenario where one of the replication slots
+ * is dropped and the drop slot statistics message is not
+ * received by the statistic collector process, now if the
+ * max_replication_slots is reduced to the actual number of
+ * replication slots that are in use and the publisher is
+ * re-started then the statistics process will not be aware of
+ * this. To avoid writing beyond the max_replication_slots
+ * this replication slot statistic information will be skipped.
+ */
+ if (max_replication_slots == nReplSlotStats)
+ {
+ ereport(pgStatRunningInCollector ? LOG : WARNING,
+ (errmsg("skipping \"%s\" replication slot statistics as pg_stat_replication_slots does not have enough slots",
+ NameStr(replSlotStats[nReplSlotStats].slotname))));
+ memset(&replSlotStats[nReplSlotStats], 0, sizeof(PgStat_ReplSlotStats));
+ goto done;
+ }
+
nReplSlotStats++;
break;
--
2.25.1
