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

2 files changed, 2 insertions, 53 deletions

diff --git a/src/backend/replication/logical/reorderbuffer.c b/src/backend/replication/logical/reorderbuffer.c
index 7afa2271bd8..52519326690 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 f66acb87206..5e2210dd7bd 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);
-}