From e44c627e72af54acdb09ec0c6175da4c302191a9 Mon Sep 17 00:00:00 2001
From: Teodor Sigaev <teodor@sigaev.ru>
Date: Mon, 10 Apr 2017 19:25:59 +0300
Subject: [PATCH] add working with fasttruncate

---
 online_analyze.c | 69 +++++++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 68 insertions(+), 1 deletion(-)

diff --git a/online_analyze.c b/online_analyze.c
index dba4226..2ef4193 100644
--- a/online_analyze.c
+++ b/online_analyze.c
@@ -30,6 +30,7 @@
 #include "postgres.h"
 
 #include "pgstat.h"
+#include "access/transam.h"
 #include "catalog/namespace.h"
 #include "commands/vacuum.h"
 #include "executor/executor.h"
@@ -602,7 +603,7 @@ makeAnalyze(Oid relOid, CmdKind operation, int64 naffected)
 				rstat->changes_since_analyze += naffected;
 				break;
 			case CK_TRUNCATE:
-				rstat->changes_since_analyze = rstat->n_tuples;
+				rstat->changes_since_analyze = 0;
 				rstat->n_tuples = 0;
 				break;
 			default:
@@ -615,15 +616,81 @@ makeAnalyze(Oid relOid, CmdKind operation, int64 naffected)
 		relstatsInit();
 }
 
+static Const*
+isFastTruncateCall(QueryDesc *queryDesc)
+{
+	TargetEntry	*te;
+	FuncExpr	*fe;
+	Const		*constval;
+
+	if (!(
+		  queryDesc->plannedstmt &&
+		  queryDesc->operation == CMD_SELECT &&
+		  queryDesc->plannedstmt->planTree &&
+		  queryDesc->plannedstmt->planTree->targetlist &&
+		  list_length(queryDesc->plannedstmt->planTree->targetlist) == 1 &&
+		  IsA(linitial(queryDesc->plannedstmt->planTree->targetlist), TargetEntry)
+		 ))
+		return NULL;
+
+	te = linitial(queryDesc->plannedstmt->planTree->targetlist);
+
+	if (!IsA(te, TargetEntry))
+		return NULL;
+
+	fe = (FuncExpr*)te->expr;
+
+	if (!(
+		  fe && IsA(fe, FuncExpr) &&
+		  fe->funcid >= FirstNormalObjectId &&
+		  fe->funcretset == false &&
+		  fe->funcresulttype == VOIDOID &&
+		  fe->funcvariadic == false &&
+		  list_length(fe->args) == 1 &&
+		  IsA(linitial(fe->args), Const)
+		 ))
+		return NULL;
+
+	constval = linitial(fe->args);
+
+	if (!(
+		  IsA(constval,Const) &&
+		  constval->consttype == TEXTOID &&
+		  strcmp(get_func_name(fe->funcid), "fasttruncate") == 0
+		 ))
+		return NULL;
+
+	return constval;
+}
+
+
+
 extern PGDLLIMPORT void onlineAnalyzeHooker(QueryDesc *queryDesc);
 void
 onlineAnalyzeHooker(QueryDesc *queryDesc)
 {
 	int64	naffected = -1;
+	Const	*constval;
 
 	if (queryDesc->estate)
 		naffected = queryDesc->estate->es_processed;
 
+	if (online_analyze_enable &&
+		(constval = isFastTruncateCall(queryDesc)) != NULL)
+	{
+		Datum		tblnamed = constval->constvalue;
+		char		*tblname = text_to_cstring(DatumGetTextP(tblnamed));
+		RangeVar	*tblvar =
+			makeRangeVarFromNameList(stringToQualifiedNameList(tblname));
+
+		makeAnalyze(RangeVarGetRelid(tblvar,
+#if PG_VERSION_NUM >= 90200
+									 NoLock,
+#endif
+									 false),
+					CK_TRUNCATE, -1);
+	}
+
 	if (online_analyze_enable && queryDesc->plannedstmt &&
 			(queryDesc->operation == CMD_INSERT ||
 			 queryDesc->operation == CMD_UPDATE ||
-- 
2.37.3