Page store: updating large rows could corrupt the database.

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

@@ -262,6 +262,7 @@ public class PageDataLeaf extends PageData {
         if (entryCount < 0) {
             Message.throwInternalError();
         }
+        freeChildren();
         firstOverflowPageId = 0;
         overflowRowSize = 0;
         rowRef = null;
@@ -274,6 +275,8 @@ public class PageDataLeaf extends PageData {
         System.arraycopy(rows, 0, newRows, 0, i);
         int startNext = i > 0 ? offsets[i - 1] : index.getPageStore().getPageSize();
         int rowLength = startNext - offsets[i];
+        int clearStart = offsets[entryCount];
+        Arrays.fill(data.getBytes(), clearStart, clearStart + rowLength, (byte) 0);
         for (int j = i; j < entryCount; j++) {
             newOffsets[j] = offsets[j + 1] + rowLength;
         }
@@ -461,9 +464,6 @@ public class PageDataLeaf extends PageData {
         if (written) {
             return;
         }
-        if (SysProperties.CHECK && firstOverflowPageId != 0 && rows[0] == null) {
-            Message.throwInternalError(toString());
-        }
         readAllRows();
         writeHead();
         if (firstOverflowPageId != 0) {
@@ -520,7 +520,16 @@ public class PageDataLeaf extends PageData {
         }
     }
 
-    void setOverflow(int overflow) throws SQLException {
+    /**
+     * Set the overflow page id.
+     *
+     * @param old the old overflow page id
+     * @param overflow the new overflow page id
+     */
+    void setOverflow(int old, int overflow) throws SQLException {
+        if (SysProperties.CHECK && old != firstOverflowPageId) {
+            Message.throwInternalError("move " + this + " " + firstOverflowPageId);
+        }
         index.getPageStore().logUndo(this, data);
         firstOverflowPageId = overflow;
         if (written) {

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

@@ -8,6 +8,7 @@ package org.h2.index;
 
 import java.sql.SQLException;
 import org.h2.constant.ErrorCode;
+import org.h2.constant.SysProperties;
 import org.h2.engine.Session;
 import org.h2.message.Message;
 import org.h2.store.Data;
@@ -228,16 +229,19 @@ public class PageDataOverflow extends Page {
         }
         if (p instanceof PageDataOverflow) {
             PageDataOverflow p1 = (PageDataOverflow) p;
-            p1.setNext(newPos);
+            p1.setNext(getPos(), newPos);
         } else {
             PageDataLeaf p1 = (PageDataLeaf) p;
-            p1.setOverflow(newPos);
+            p1.setOverflow(getPos(), newPos);
         }
         store.update(p);
         store.free(getPos(), true);
     }
 
-    private void setNext(int nextPage) throws SQLException {
+    private void setNext(int old, int nextPage) throws SQLException {
+        if (SysProperties.CHECK && old != this.nextPage) {
+            Message.throwInternalError("move " + this + " " + nextPage);
+        }
         store.logUndo(this, data);
         this.nextPage = nextPage;
         data.setInt(START_NEXT_OVERFLOW, nextPage);