Better cleanup of view index caches.

h2/src/main/org/h2/engine/Session.java

@@ -10,6 +10,7 @@ import java.util.HashMap;
 import java.util.HashSet;
 import java.util.Iterator;
 import java.util.LinkedList;
+import java.util.Map;
 import java.util.Random;
 import org.h2.api.ErrorCode;
 import org.h2.command.Command;
@@ -112,7 +113,8 @@ public class Session extends SessionWithState {
     private long modificationMetaID = -1;
     private SubQueryInfo subQueryInfo;
     private int parsingView;
-    private SmallLRUCache<Object, ViewIndex> viewIndexCache;
+    private volatile SmallLRUCache<Object, ViewIndex> viewIndexCache;
+    private HashMap<Object, ViewIndex> subQueryIndexCache;
 
     /**
      * Temporary LOBs from result sets. Those are kept for some time. The
@@ -1315,11 +1317,20 @@ public class Session extends SessionWithState {
         }
     }
 
-    public SmallLRUCache<Object, ViewIndex> getViewIndexCache() {
-        if (viewIndexCache == null) {
-            viewIndexCache = SmallLRUCache.newInstance(Constants.VIEW_INDEX_CACHE_SIZE);
+    public Map<Object, ViewIndex> getViewIndexCache(boolean subQuery) {
+        if (subQuery) {
+            // for sub-queries we don't need to use LRU because it should not grow too large
+            // for a single query and by the end of the statement we will drop the whole cache
+            if (subQueryIndexCache == null) {
+                subQueryIndexCache = New.hashMap();
+            }
+            return subQueryIndexCache;
+        }
+        SmallLRUCache<Object, ViewIndex> cache = viewIndexCache;
+        if (cache == null) {
+            viewIndexCache = cache = SmallLRUCache.newInstance(Constants.VIEW_INDEX_CACHE_SIZE);
         }
-        return viewIndexCache;
+        return cache;
     }
 
     /**
@@ -1499,9 +1510,14 @@ public class Session extends SessionWithState {
      */
     public void endStatement() {
         startStatement = -1;
+        subQueryIndexCache = null;
         closeTemporaryResults();
     }
 
+    public void clearViewIndexCache() {
+        viewIndexCache = null;
+    }
+
     @Override
     public void addTemporaryLob(Value v) {
         if (v.getType() != Value.CLOB && v.getType() != Value.BLOB) {

h2/src/main/org/h2/table/TableView.java

@@ -8,6 +8,7 @@ package org.h2.table;
 import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.HashSet;
+import java.util.Map;
 import org.h2.api.ErrorCode;
 import org.h2.command.Prepared;
 import org.h2.command.dml.Query;
@@ -29,7 +30,6 @@ import org.h2.result.Row;
 import org.h2.result.SortOrder;
 import org.h2.schema.Schema;
 import org.h2.util.New;
-import org.h2.util.SmallLRUCache;
 import org.h2.util.StatementBuilder;
 import org.h2.util.StringUtils;
 import org.h2.value.Value;
@@ -228,14 +228,12 @@ public class TableView extends Table {
         PlanItem item = new PlanItem();
         item.cost = index.getCost(session, masks, filters, filter, sortOrder);
         final CacheKey cacheKey = new CacheKey(masks, this);
-        SmallLRUCache<Object, ViewIndex> indexCache = session.getViewIndexCache();
+        Map<Object, ViewIndex> indexCache = session.getViewIndexCache(topQuery != null);
         ViewIndex i = indexCache.get(cacheKey);
-        if (i != null) {
-            item.setIndex(i);
-            return item;
+        if (i == null) {
+            i = new ViewIndex(this, index, session, masks, filters, filter, sortOrder);
+            indexCache.put(cacheKey, i);
         }
-        i = new ViewIndex(this, index, session, masks, filters, filter, sortOrder);
-        indexCache.put(cacheKey, i);
         item.setIndex(i);
         return item;
     }
@@ -257,6 +255,10 @@ public class TableView extends Table {
         return true;
     }
 
+    public Query getTopQuery() {
+        return topQuery;
+    }
+
     @Override
     public String getDropSQL() {
         return "DROP VIEW IF EXISTS " + getSQL() + " CASCADE";
@@ -397,6 +399,9 @@ public class TableView extends Table {
         database.removeMeta(session, getId());
         querySQL = null;
         index = null;
+        for (Session s : database.getSessions(true)) {
+            s.clearViewIndexCache();
+        }
         invalidate();
     }