From 58675e5fe74be3509bd3c882c4326b9f639bd249 Mon Sep 17 00:00:00 2001
From: Teodor Sigaev <teodor@sigaev.ru>
Date: Fri, 7 Apr 2017 17:10:56 +0300
Subject: [PATCH] try to optimize reread stat

---
 online_analyze.c | 120 +++++++++++++++++++++++++++++++++++++----------
 1 file changed, 94 insertions(+), 26 deletions(-)

diff --git a/online_analyze.c b/online_analyze.c
index 50d8aca..c94497c 100644
--- a/online_analyze.c
+++ b/online_analyze.c
@@ -73,6 +73,16 @@ static ExecutorEnd_hook_type oldExecutorEndHook = NULL;
 static ProcessUtility_hook_type	oldProcessUtilityHook = NULL;
 #endif
 
+typedef enum CmdKind
+{
+	CK_SELECT = CMD_SELECT,
+	CK_UPDATE = CMD_UPDATE,
+	CK_INSERT = CMD_INSERT,
+	CK_DELETE = CMD_DELETE,
+	CK_TRUNCATE,
+	CK_CREATE
+} CmdKind;
+
 typedef enum
 {
 	OATT_ALL		= 0x03,
@@ -342,7 +352,7 @@ makeRangeVarFromOid(Oid relOid)
 #endif
 
 static void
-makeAnalyze(Oid relOid, CmdType operation, int32 naffected)
+makeAnalyze(Oid relOid, CmdKind operation, int32 naffected)
 {
 	TimestampTz				now = GetCurrentTimestamp();
 	Relation				rel;
@@ -422,15 +432,20 @@ makeAnalyze(Oid relOid, CmdType operation, int32 naffected)
 	else
 		rstat = &dummyrstat; /* found == false for following if */
 
-	if (found == false || rstat->rereadStat == true || naffected == 0)
+	if (!found)
 	{
+		MemSet(rstat, 0, sizeof(*rstat));
+		rstat->tableid = relOid;
+		newTable = true;
+	}
 
-		if (!found)
-		{
-			MemSet(rstat, 0, sizeof(*rstat));
-			rstat->tableid = relOid;
-		}
-		Assert(rstat->tableid == relOid);
+	Assert(rstat->tableid == relOid);
+
+	if (operation != CK_TRUNCATE &&
+		(found == false || rstat->rereadStat == true))
+	{
+
+		rstat->rereadStat = false;
 
 		tabentry = pgstat_fetch_stat_tabentry(relOid);
 
@@ -447,16 +462,15 @@ makeAnalyze(Oid relOid, CmdType operation, int32 naffected)
 			rstat->autovac_analyze_timestamp =
 				tabentry->autovac_analyze_timestamp;
 			rstat->analyze_timestamp = tabentry->analyze_timestamp;
-			rstat->rereadStat = false;
-		}
-		else
-		{
-			newTable = true;
-			rstat->rereadStat = true;
 		}
 	}
 
-	if (newTable || (
+	if (naffected == 0)
+		rstat->rereadStat = true;
+
+	if (newTable ||
+		/* force analyze from after truncate */
+		operation == CK_TRUNCATE || (
 		/* do not analyze too often, if both stamps are exceeded the go */
 		TimestampDifferenceExceeds(rstat->analyze_timestamp, now, online_analyze_min_interval) &&
 		TimestampDifferenceExceeds(rstat->autovac_analyze_timestamp, now, online_analyze_min_interval) &&
@@ -533,7 +547,25 @@ makeAnalyze(Oid relOid, CmdType operation, int32 naffected)
 
 		rstat->autovac_analyze_timestamp = now;
 		rstat->changes_since_analyze = 0;
-		rstat->rereadStat = true;
+
+		switch(operation)
+		{
+			case CK_INSERT:
+				rstat->n_tuples += naffected;
+				break;
+			case CK_UPDATE:
+				rstat->n_tuples += naffected;
+				rstat->rereadStat = true;
+				break;
+			case CK_DELETE:
+				rstat->rereadStat = true;
+				break;
+			case CK_TRUNCATE:
+				rstat->n_tuples = 0;
+				break;
+			default:
+				break;
+		}
 
 		/* update last analyze timestamp in local memory of backend */
 		if (tabentry)
@@ -553,7 +585,25 @@ makeAnalyze(Oid relOid, CmdType operation, int32 naffected)
 		if (tabentry)
 			tabentry->changes_since_analyze += naffected;
 #endif
-		rstat->changes_since_analyze += naffected;
+		switch(operation)
+		{
+			case CK_INSERT:
+				rstat->changes_since_analyze += naffected;
+				rstat->n_tuples += naffected;
+				break;
+			case CK_UPDATE:
+				rstat->changes_since_analyze += 2 * naffected;
+				rstat->n_tuples += naffected;
+			case CK_DELETE:
+				rstat->changes_since_analyze += naffected;
+				break;
+			case CK_TRUNCATE:
+				rstat->changes_since_analyze = rstat->n_tuples;
+				rstat->n_tuples = 0;
+				break;
+			default:
+				break;
+		}
 	}
 
 	/* Reset local cache if we are over limit */
@@ -600,7 +650,7 @@ onlineAnalyzeHooker(QueryDesc *queryDesc)
 				RangeTblEntry	*rte = list_nth(queryDesc->plannedstmt->rtable, n-1);
 
 				if (rte->rtekind == RTE_RELATION)
-					makeAnalyze(rte->relid, queryDesc->operation, naffected);
+					makeAnalyze(rte->relid, (CmdKind)queryDesc->operation, naffected);
 			}
 		}
 	}
@@ -629,7 +679,8 @@ onlineAnalyzeHookerUtility(
 							ParamListInfo params, bool isTopLevel,
 #endif
 							DestReceiver *dest, char *completionTag) {
-	RangeVar	*tblname = NULL;
+	List		*tblnames = NIL;
+	CmdKind		op = CK_INSERT;
 #if PG_VERSION_NUM >= 100000
 	Node		*parsetree = NULL;
 
@@ -637,10 +688,21 @@ onlineAnalyzeHookerUtility(
 		parsetree = pstmt->utilityStmt;
 #endif
 
-	if (parsetree && IsA(parsetree, CreateTableAsStmt) &&
-		((CreateTableAsStmt*)parsetree)->into &&
-		online_analyze_enable)
-		tblname = (RangeVar*)copyObject(((CreateTableAsStmt*)parsetree)->into->rel);
+	if (parsetree && online_analyze_enable)
+	{
+		if (IsA(parsetree, CreateTableAsStmt) &&
+			((CreateTableAsStmt*)parsetree)->into)
+		{
+			tblnames =
+				list_make1((RangeVar*)copyObject(((CreateTableAsStmt*)parsetree)->into->rel));
+			op = CK_CREATE;
+		}
+		else if (IsA(parsetree, TruncateStmt))
+		{
+			tblnames = list_copy(((TruncateStmt*)parsetree)->relations);
+			op = CK_TRUNCATE;
+		}
+	}
 
 #if PG_VERSION_NUM >= 100000
 #define parsetree pstmt
@@ -673,10 +735,16 @@ onlineAnalyzeHookerUtility(
 #undef parsetree
 #endif
 
-	if (tblname) {
-		Oid	tblOid = RangeVarGetRelid(tblname, NoLock, true);
+	if (tblnames) {
+		ListCell	*l;
 
-		makeAnalyze(tblOid, CMD_INSERT, -1);
+		foreach(l, tblnames)
+		{
+			RangeVar	*tblname = (RangeVar*)lfirst(l);
+			Oid	tblOid = RangeVarGetRelid(tblname, NoLock, true);
+
+			makeAnalyze(tblOid, op, -1);
+		}
 	}
 }
 #endif
-- 
2.37.3