Switched to use linked list like approach + allow to get info from upper levels

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

@@ -5,7 +5,6 @@
  */
 package org.h2.engine;
 
-import java.util.ArrayDeque;
 import java.util.ArrayList;
 import java.util.HashMap;
 import java.util.HashSet;
@@ -110,7 +109,7 @@ public class Session extends SessionWithState {
     private final int queryCacheSize;
     private SmallLRUCache<String, Command> queryCache;
     private long modificationMetaID = -1;
-    private ArrayDeque<SubQueryInfo> subQueryInfoStack = new ArrayDeque<SubQueryInfo>();
+    private SubQueryInfo subQueryInfo;
     private int parsingView;
 
     /**
@@ -145,18 +144,12 @@ public class Session extends SessionWithState {
         this.currentSchemaName = Constants.SCHEMA_MAIN;
     }
 
-    public void pushSubQueryInfo(SubQueryInfo subQueryInfo) {
-        assert subQueryInfo != null;
-        subQueryInfoStack.addLast(subQueryInfo);
-    }
-
-    public void popSubQueryInfo(SubQueryInfo subQueryInfo) {
-        SubQueryInfo popped = subQueryInfoStack.pollLast();
-        assert popped == subQueryInfo;
+    public void setSubQueryInfo(SubQueryInfo subQueryInfo) {
+        this.subQueryInfo = subQueryInfo;
     }
 
     public SubQueryInfo getSubQueryInfo() {
-        return subQueryInfoStack.peekLast();
+        return subQueryInfo;
     }
 
     public void setParsingView(boolean parsingView) {

h2/src/main/org/h2/index/ViewIndex.java

@@ -198,12 +198,14 @@ public class ViewIndex extends BaseIndex implements SpatialIndex {
     private static Query prepareSubQuery(String sql, Session session, int[] masks,
             TableFilter[] filters, int filter, SortOrder sortOrder, boolean preliminary) {
         Prepared p;
-        SubQueryInfo info = new SubQueryInfo(masks, filters, filter, sortOrder, preliminary);
-        session.pushSubQueryInfo(info);
+        SubQueryInfo upper = session.getSubQueryInfo();
+        SubQueryInfo info = new SubQueryInfo(upper,
+                masks, filters, filter, sortOrder, preliminary);
+        session.setSubQueryInfo(info);
         try {
             p = session.prepare(sql, true);
         } finally {
-            session.popSubQueryInfo(info);
+            session.setSubQueryInfo(upper);
         }
         return (Query) p;
     }

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

@@ -20,8 +20,10 @@ public class SubQueryInfo {
     private int filter;
     private SortOrder sortOrder;
     private boolean preliminary;
+    private SubQueryInfo upper;
 
     /**
+     * @param upper upper level sub-query if any
      * @param masks index conditions masks
      * @param filters table filters
      * @param filter current filter
@@ -29,8 +31,9 @@ public class SubQueryInfo {
      * @param preliminary if this is a preliminary query optimization 
      *          without global conditions
      */
-    public SubQueryInfo(int[] masks, TableFilter[] filters, int filter, 
+    public SubQueryInfo(SubQueryInfo upper, int[] masks, TableFilter[] filters, int filter,
             SortOrder sortOrder, boolean preliminary) {
+        this.upper = upper;
         this.masks = masks;
         this.filters = filters;
         this.filter = filter;
@@ -38,6 +41,10 @@ public class SubQueryInfo {
         this.preliminary = preliminary;
     }
 
+    public SubQueryInfo getUpper() {
+        return upper;
+    }
+
     public int[] getMasks() {
         return masks;
     }