From 4ff85471d1e2b5d9787dd19667467a1498d2e876 Mon Sep 17 00:00:00 2001
From: Teodor Sigaev <teodor@sigaev.ru>
Date: Thu, 10 Nov 2016 19:36:48 +0300
Subject: [PATCH] do not sore permanent table in local cache and add limit for
 table cache

---
 README.online_analyze |  3 ++
 online_analyze.c      | 66 +++++++++++++++++++++++++++++++++++++++----
 2 files changed, 63 insertions(+), 6 deletions(-)

diff --git a/README.online_analyze b/README.online_analyze
index bb4491c..b181da5 100644
--- a/README.online_analyze
+++ b/README.online_analyze
@@ -34,4 +34,7 @@ online_analyze.include_tables = ""
 	List of tables which will online analyze
 	online_analyze.include_tables overwrites online_analyze.exclude_tables.
 
+online_analyze.capacity_threshold = 100000
+	Maximum number of temporary tables to store in local cache
+
 Author: Teodor Sigaev <teodor@sigaev.ru>
diff --git a/online_analyze.c b/online_analyze.c
index d16b233..93276ab 100644
--- a/online_analyze.c
+++ b/online_analyze.c
@@ -61,6 +61,7 @@ static bool online_analyze_enable = true;
 static bool online_analyze_verbose = true;
 static double online_analyze_scale_factor = 0.1;
 static int online_analyze_threshold = 50;
+static int online_analyze_capacity_threshold = 100000;
 static double online_analyze_min_interval = 10000;
 
 static ExecutorEnd_hook_type oldExecutorEndHook = NULL;
@@ -105,8 +106,11 @@ typedef struct OnlineAnalyzeTableStat {
 	TimestampTz		analyze_timestamp;
 } OnlineAnalyzeTableStat;
 
+static	MemoryContext	onlineAnalyzeMemoryContext = NULL;
 static	HTAB	*relstats = NULL;
 
+static void relstatsInit();
+
 static int
 oid_cmp(const void *a, const void *b)
 {
@@ -337,16 +341,17 @@ makeAnalyze(Oid relOid, CmdType operation, int32 naffected)
 	TimestampTz				now = GetCurrentTimestamp();
 	Relation				rel;
 	OnlineAnalyzeTableType	reltype;
-	bool					found,
+	bool					found = false,
 							newTable = false;
-	OnlineAnalyzeTableStat	*rstat;
+	OnlineAnalyzeTableStat	*rstat,
+							dummyrstat;
 	PgStat_StatTabEntry		*tabentry = NULL;
 
 	if (relOid == InvalidOid)
 		return;
 
 	if (naffected == 0)
-		/* return if there is not changes */
+		/* return if there is no changes */
 		return;
 	else if (naffected < 0)
 		/* number if affected rows is unknown */
@@ -401,7 +406,15 @@ makeAnalyze(Oid relOid, CmdType operation, int32 naffected)
 			break;
 	}
 
-	rstat = hash_search(relstats, &relOid, HASH_ENTER, &found);
+	/*
+	 * Do not store data about persistent table in local memory because we
+	 * could not track changes of them: they could be changed by another
+	 * backends. So always get a pgstat table entry.
+	 */
+	if (reltype == OATT_TEMPORARY)
+		rstat = hash_search(relstats, &relOid, HASH_ENTER, &found);
+	else
+		rstat = &dummyrstat; /* found == false for following if */
 
 	if (found == false || rstat->rereadStat == true || naffected == 0)
 	{
@@ -518,8 +531,10 @@ makeAnalyze(Oid relOid, CmdType operation, int32 naffected)
 
 		/* update last analyze timestamp in local memory of backend */
 		if (tabentry)
+		{
 			tabentry->analyze_timestamp = now;
-
+			tabentry->changes_since_analyze = 0;
+		}
 #if 0
 		/* force reload stat for new table */
 		if (newTable)
@@ -529,11 +544,15 @@ makeAnalyze(Oid relOid, CmdType operation, int32 naffected)
 	else
 	{
 #if PG_VERSION_NUM >= 90000
-		if (tabentry != NULL)
+		if (tabentry)
 			tabentry->changes_since_analyze += naffected;
 #endif
 		rstat->changes_since_analyze += naffected;
 	}
+
+	/* Reset local cache if we are over limit */
+	if (hash_get_num_entries(relstats) > online_analyze_capacity_threshold)
+		relstatsInit();
 }
 
 extern PGDLLIMPORT void onlineAnalyzeHooker(QueryDesc *queryDesc);
@@ -636,6 +655,20 @@ relstatsInit()
 	hash_ctl.hash = oid_hash;
 	flags |= HASH_FUNCTION;
 
+	if (onlineAnalyzeMemoryContext)
+	{
+		Assert(relstats != NULL);
+		MemoryContextReset(onlineAnalyzeMemoryContext);
+	}
+	else
+	{
+		Assert(relstats == NULL);
+		onlineAnalyzeMemoryContext =
+			AllocSetContextCreate(CacheMemoryContext,
+								  "online_analyze storage context",
+								  ALLOCSET_DEFAULT_SIZES);
+	}
+
 	hash_ctl.hcxt = AllocSetContextCreate(CacheMemoryContext,
 										  "online_analyze storage context",
 										  ALLOCSET_DEFAULT_SIZES);
@@ -746,6 +779,27 @@ _PG_init(void)
 		NULL
 	);
 
+	DefineCustomIntVariable(
+		"online_analyze.capacity_threshold",
+		"Max local cache table capacity",
+		"Max local cache table capacity",
+		&online_analyze_capacity_threshold,
+#if PG_VERSION_NUM >= 80400
+		online_analyze_capacity_threshold,
+#endif
+		0,
+		0x7fffffff,
+		PGC_USERSET,
+#if PG_VERSION_NUM >= 80400
+		GUC_NOT_IN_SAMPLE,
+#if PG_VERSION_NUM >= 90100
+		NULL,
+#endif
+#endif
+		NULL,
+		NULL
+	);
+
 	DefineCustomRealVariable(
 		"online_analyze.min_interval",
 		"minimum time interval between analyze call (in milliseconds)",
-- 
2.37.3