Revert "Track statistics for spilling of changes from ReorderBuffer".

The stats with this commit was available only for WALSenders, however,
users might want to see for backends doing logical decoding via SQL API.
Then, users might want to reset and access these stats across server
restart which was not possible with the current patch.

List of commits reverted:

caa3c4242c   Don't call elog() while holding spinlock.
e641b2a995   Doc: Update the documentation for spilled transaction
statistics.
5883f5fe27   Fix unportable printf format introduced in commit 9290ad198.
9290ad198b   Track statistics for spilling of changes from ReorderBuffer.

Additionaly, remove the release notes entry for this feature.

Backpatch-through: 13, where it was introduced
Discussion: https://postgr.es/m/CA+fd4k5_pPAYRTDrO2PbtTOe0eHQpBvuqmCr8ic39uTNmR49Eg@mail.gmail.com

8 files changed, 9 insertions, 82 deletions

diff --git a/src/backend/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index 73676d04cf..b6d35c2d11 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -785,10 +785,7 @@ CREATE VIEW pg_stat_replication AS
             W.replay_lag,
             W.sync_priority,
             W.sync_state,
-            W.reply_time,
-            W.spill_txns,
-            W.spill_count,
-            W.spill_bytes
+            W.reply_time
     FROM pg_stat_get_activity(NULL) AS S
         JOIN pg_stat_get_wal_senders() AS W ON (S.pid = W.pid)
         LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
diff --git a/src/backend/replication/logical/reorderbuffer.c b/src/backend/replication/logical/reorderbuffer.c
index 7afa2271bd..5251932669 100644
--- a/src/backend/replication/logical/reorderbuffer.c
+++ b/src/backend/replication/logical/reorderbuffer.c
@@ -317,10 +317,6 @@ ReorderBufferAllocate(void)
 	buffer->outbufsize = 0;
 	buffer->size = 0;
 
-	buffer->spillCount = 0;
-	buffer->spillTxns = 0;
-	buffer->spillBytes = 0;
-
 	buffer->current_restart_decoding_lsn = InvalidXLogRecPtr;
 
 	dlist_init(&buffer->toplevel_by_lsn);
@@ -2418,7 +2414,6 @@ ReorderBufferSerializeTXN(ReorderBuffer *rb, ReorderBufferTXN *txn)
 	int			fd = -1;
 	XLogSegNo	curOpenSegNo = 0;
 	Size		spilled = 0;
-	Size		size = txn->size;
 
 	elog(DEBUG2, "spill %u changes in XID %u to disk",
 		 (uint32) txn->nentries_mem, txn->xid);
@@ -2477,13 +2472,6 @@ ReorderBufferSerializeTXN(ReorderBuffer *rb, ReorderBufferTXN *txn)
 		spilled++;
 	}
 
-	/* update the statistics */
-	rb->spillCount += 1;
-	rb->spillBytes += size;
-
-	/* Don't consider already serialized transactions. */
-	rb->spillTxns += rbtxn_is_serialized(txn) ? 0 : 1;
-
 	Assert(spilled == txn->nentries_mem);
 	Assert(dlist_is_empty(&txn->changes));
 	txn->nentries_mem = 0;
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index f66acb8720..5e2210dd7b 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -254,7 +254,6 @@ static bool TransactionIdInRecentPast(TransactionId xid, uint32 epoch);
 
 static void WalSndSegmentOpen(XLogReaderState *state, XLogSegNo nextSegNo,
 							  TimeLineID *tli_p);
-static void UpdateSpillStats(LogicalDecodingContext *ctx);
 
 
 /* Initialize walsender process before entering the main command loop */
@@ -1348,8 +1347,7 @@ WalSndWriteData(LogicalDecodingContext *ctx, XLogRecPtr lsn, TransactionId xid,
 /*
  * LogicalDecodingContext 'update_progress' callback.
  *
- * Write the current position to the lag tracker (see XLogSendPhysical),
- * and update the spill statistics.
+ * Write the current position to the lag tracker (see XLogSendPhysical).
  */
 static void
 WalSndUpdateProgress(LogicalDecodingContext *ctx, XLogRecPtr lsn, TransactionId xid)
@@ -1368,11 +1366,6 @@ WalSndUpdateProgress(LogicalDecodingContext *ctx, XLogRecPtr lsn, TransactionId
 
 	LagTrackerWrite(lsn, now);
 	sendTime = now;
-
-	/*
-	 * Update statistics about transactions that spilled to disk.
-	 */
-	UpdateSpillStats(ctx);
 }
 
 /*
@@ -2418,9 +2411,6 @@ InitWalSenderSlot(void)
 			walsnd->sync_standby_priority = 0;
 			walsnd->latch = &MyProc->procLatch;
 			walsnd->replyTime = 0;
-			walsnd->spillTxns = 0;
-			walsnd->spillCount = 0;
-			walsnd->spillBytes = 0;
 			SpinLockRelease(&walsnd->mutex);
 			/* don't need the lock anymore */
 			MyWalSnd = (WalSnd *) walsnd;
@@ -3256,7 +3246,7 @@ offset_to_interval(TimeOffset offset)
 Datum
 pg_stat_get_wal_senders(PG_FUNCTION_ARGS)
 {
-#define PG_STAT_GET_WAL_SENDERS_COLS	15
+#define PG_STAT_GET_WAL_SENDERS_COLS	12
 	ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
 	TupleDesc	tupdesc;
 	Tuplestorestate *tupstore;
@@ -3310,9 +3300,6 @@ pg_stat_get_wal_senders(PG_FUNCTION_ARGS)
 		int			pid;
 		WalSndState state;
 		TimestampTz replyTime;
-		int64		spillTxns;
-		int64		spillCount;
-		int64		spillBytes;
 		bool		is_sync_standby;
 		Datum		values[PG_STAT_GET_WAL_SENDERS_COLS];
 		bool		nulls[PG_STAT_GET_WAL_SENDERS_COLS];
@@ -3336,9 +3323,6 @@ pg_stat_get_wal_senders(PG_FUNCTION_ARGS)
 		applyLag = walsnd->applyLag;
 		priority = walsnd->sync_standby_priority;
 		replyTime = walsnd->replyTime;
-		spillTxns = walsnd->spillTxns;
-		spillCount = walsnd->spillCount;
-		spillBytes = walsnd->spillBytes;
 		SpinLockRelease(&walsnd->mutex);
 
 		/*
@@ -3436,11 +3420,6 @@ pg_stat_get_wal_senders(PG_FUNCTION_ARGS)
 				nulls[11] = true;
 			else
 				values[11] = TimestampTzGetDatum(replyTime);
-
-			/* spill to disk */
-			values[12] = Int64GetDatum(spillTxns);
-			values[13] = Int64GetDatum(spillCount);
-			values[14] = Int64GetDatum(spillBytes);
 		}
 
 		tuplestore_putvalues(tupstore, tupdesc, values, nulls);
@@ -3677,21 +3656,3 @@ LagTrackerRead(int head, XLogRecPtr lsn, TimestampTz now)
 	Assert(time != 0);
 	return now - time;
 }
-
-static void
-UpdateSpillStats(LogicalDecodingContext *ctx)
-{
-	ReorderBuffer *rb = ctx->reorder;
-
-	elog(DEBUG2, "UpdateSpillStats: updating stats %p %lld %lld %lld",
-		 rb,
-		 (long long) rb->spillTxns,
-		 (long long) rb->spillCount,
-		 (long long) rb->spillBytes);
-
-	SpinLockAcquire(&MyWalSnd->mutex);
-	MyWalSnd->spillTxns = rb->spillTxns;
-	MyWalSnd->spillCount = rb->spillCount;
-	MyWalSnd->spillBytes = rb->spillBytes;
-	SpinLockRelease(&MyWalSnd->mutex);
-}
diff --git a/src/include/catalog/catversion.h b/src/include/catalog/catversion.h
index ee58586569..6b3aa7c006 100644
--- a/src/include/catalog/catversion.h
+++ b/src/include/catalog/catversion.h
@@ -53,6 +53,6 @@
  */
 
 /*							yyyymmddN */
-#define CATALOG_VERSION_NO	202007121
+#define CATALOG_VERSION_NO	202007131
 
 #endif
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index d81467af19..95604e988a 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5240,9 +5240,9 @@
   proname => 'pg_stat_get_wal_senders', prorows => '10', proisstrict => 'f',
   proretset => 't', provolatile => 's', proparallel => 'r',
   prorettype => 'record', proargtypes => '',
-  proallargtypes => '{int4,text,pg_lsn,pg_lsn,pg_lsn,pg_lsn,interval,interval,interval,int4,text,timestamptz,int8,int8,int8}',
-  proargmodes => '{o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
-  proargnames => '{pid,state,sent_lsn,write_lsn,flush_lsn,replay_lsn,write_lag,flush_lag,replay_lag,sync_priority,sync_state,reply_time,spill_txns,spill_count,spill_bytes}',
+  proallargtypes => '{int4,text,pg_lsn,pg_lsn,pg_lsn,pg_lsn,interval,interval,interval,int4,text,timestamptz}',
+  proargmodes => '{o,o,o,o,o,o,o,o,o,o,o,o}',
+  proargnames => '{pid,state,sent_lsn,write_lsn,flush_lsn,replay_lsn,write_lag,flush_lag,replay_lag,sync_priority,sync_state,reply_time}',
   prosrc => 'pg_stat_get_wal_senders' },
 { oid => '3317', descr => 'statistics: information about WAL receiver',
   proname => 'pg_stat_get_wal_receiver', proisstrict => 'f', provolatile => 's',
diff --git a/src/include/replication/reorderbuffer.h b/src/include/replication/reorderbuffer.h
index 626ecf4dc9..019bd382de 100644
--- a/src/include/replication/reorderbuffer.h
+++ b/src/include/replication/reorderbuffer.h
@@ -413,17 +413,6 @@ struct ReorderBuffer
 
 	/* memory accounting */
 	Size		size;
-
-	/*
-	 * Statistics about transactions spilled to disk.
-	 *
-	 * A single transaction may be spilled repeatedly, which is why we keep
-	 * two different counters. For spilling, the transaction counter includes
-	 * both toplevel transactions and subtransactions.
-	 */
-	int64		spillCount;		/* spill-to-disk invocation counter */
-	int64		spillTxns;		/* number of transactions spilled to disk  */
-	int64		spillBytes;		/* amount of data spilled to disk */
 };
 
 
diff --git a/src/include/replication/walsender_private.h b/src/include/replication/walsender_private.h
index 734acec2a4..509856c057 100644
--- a/src/include/replication/walsender_private.h
+++ b/src/include/replication/walsender_private.h
@@ -78,11 +78,6 @@ typedef struct WalSnd
 	 * Timestamp of the last message received from standby.
 	 */
 	TimestampTz replyTime;
-
-	/* Statistics for transactions spilled to disk. */
-	int64		spillTxns;
-	int64		spillCount;
-	int64		spillBytes;
 } WalSnd;
 
 extern WalSnd *MyWalSnd;
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 93bb2159ca..fa436f2caa 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -2002,12 +2002,9 @@ pg_stat_replication| SELECT s.pid,
     w.replay_lag,
     w.sync_priority,
     w.sync_state,
-    w.reply_time,
-    w.spill_txns,
-    w.spill_count,
-    w.spill_bytes
+    w.reply_time
    FROM ((pg_stat_get_activity(NULL::integer) s(datid, pid, usesysid, application_name, state, query, wait_event_type, wait_event, xact_start, query_start, backend_start, state_change, client_addr, client_hostname, client_port, backend_xid, backend_xmin, backend_type, ssl, sslversion, sslcipher, sslbits, sslcompression, ssl_client_dn, ssl_client_serial, ssl_issuer_dn, gss_auth, gss_princ, gss_enc, leader_pid)
-     JOIN pg_stat_get_wal_senders() w(pid, state, sent_lsn, write_lsn, flush_lsn, replay_lsn, write_lag, flush_lag, replay_lag, sync_priority, sync_state, reply_time, spill_txns, spill_count, spill_bytes) ON ((s.pid = w.pid)))
+     JOIN pg_stat_get_wal_senders() w(pid, state, sent_lsn, write_lsn, flush_lsn, replay_lsn, write_lag, flush_lag, replay_lag, sync_priority, sync_state, reply_time) ON ((s.pid = w.pid)))
      LEFT JOIN pg_authid u ON ((s.usesysid = u.oid)));
 pg_stat_slru| SELECT s.name,
     s.blks_zeroed,