Page store: better memory usage calculation.

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

@@ -253,8 +253,8 @@ public abstract class PageBtree extends Page {
      * @return number of double words (4 bytes)
      */
     public int getMemorySize() {
-        // double the byte array size
-        return index.getPageStore().getPageSize() >> 1;
+        // four times the byte array size
+        return index.getPageStore().getPageSize();
     }
 
 }

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

@@ -205,8 +205,8 @@ abstract class PageData extends Page {
      * @return number of double words (4 bytes)
      */
     public int getMemorySize() {
-        // double the byte array size
-        return index.getPageStore().getPageSize() >> 1;
+        // four times the byte array size
+        return index.getPageStore().getPageSize();
     }
 
     int getParentPageId() {

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

@@ -65,6 +65,8 @@ public class PageDataLeaf extends PageData {
 
     private int columnCount;
 
+    private int memorySize;
+
     private PageDataLeaf(PageScanIndex index, int pageId, Data data) {
         super(index, pageId, data);
     }
@@ -185,6 +187,7 @@ public class PageDataLeaf extends PageData {
         newOffsets[x] = offset;
         newKeys[x] = row.getPos();
         newRows[x] = row;
+        memorySize += row.getMemorySize();
         offsets = newOffsets;
         keys = newKeys;
         rows = newRows;
@@ -237,6 +240,10 @@ public class PageDataLeaf extends PageData {
     private void removeRow(int i) throws SQLException {
         written = false;
         readAllRows();
+        Row r = rows[i];
+        if (r != null) {
+            memorySize += r.getMemorySize();
+        }
         entryCount--;
         if (entryCount < 0) {
             Message.throwInternalError();
@@ -305,6 +312,7 @@ int checkRequired;
                 rowRef = new SoftReference<Row>(r);
             } else {
                 rows[at] = r;
+                memorySize += r.getMemorySize();
             }
         }
         return r;
@@ -484,4 +492,8 @@ int checkRequired;
         index.getPageStore().updateRecord(this, true, data);
     }
 
+    public int getMemorySize() {
+        return index.getMemorySizePerPage();
+    }
+
 }

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

@@ -45,6 +45,7 @@ public class PageScanIndex extends PageIndex implements RowIndex {
     private HashMap<Integer, Integer> sessionRowCount;
     private int mainIndexColumn = -1;
     private SQLException fastDuplicateKeyException;
+    private int memorySizePerPage;
 
     public PageScanIndex(TableData table, int id, IndexColumn[] columns, IndexType indexType, int headPos, Session session) throws SQLException {
         initBaseIndex(table, id, table.getName() + "_TABLE_SCAN", columns, indexType);
@@ -81,6 +82,11 @@ public class PageScanIndex extends PageIndex implements RowIndex {
         }
         table.setRowCount(rowCount);
         fastDuplicateKeyException = super.getDuplicateKeyException();
+        // estimate the memory usage as follows:
+        // the less column, the more memory is required, because the more rows fit on a page
+        memorySizePerPage = store.getPageSize();
+        int estimatedRowsPerPage =  store.getPageSize() / ((1 + columns.length) * 8);
+        memorySizePerPage += estimatedRowsPerPage * 64;
     }
 
     public SQLException getDuplicateKeyException() {
@@ -480,4 +486,8 @@ public class PageScanIndex extends PageIndex implements RowIndex {
         return mainIndexColumn;
     }
 
+    int getMemorySizePerPage() {
+        return memorySizePerPage;
+    }
+
 }

h2/src/main/org/h2/store/PageInputStream.java

@@ -148,4 +148,8 @@ public class PageInputStream extends InputStream {
         return data.getPos();
     }
 
+    public void close() {
+        // nothing to do
+    }
+
 }

h2/src/main/org/h2/store/PageLog.java

@@ -8,6 +8,7 @@ package org.h2.store;
 
 import java.io.EOFException;
 import java.io.IOException;
+import java.io.OutputStream;
 import java.sql.SQLException;
 import java.util.HashMap;
 import org.h2.compress.CompressLZF;
@@ -120,6 +121,7 @@ public class PageLog {
 
     private Data outBuffer;
     private PageInputStream pageIn;
+    private OutputStream pageBuffer;
     private PageOutputStream pageOut;
     private DataReader in;
     private int firstTrunkPage;
@@ -180,6 +182,9 @@ public class PageLog {
         this.firstTrunkPage = firstTrunkPage;
         pageOut = new PageOutputStream(store, firstTrunkPage, undoAll, atEnd);
         pageOut.reserve(1);
+        // TODO maybe buffer to improve speed
+        pageBuffer = pageOut;
+        // pageBuffer = new BufferedOutputStream(pageOut, 8 * 1024);
         store.setLogFirstPage(firstTrunkPage, pageOut.getCurrentDataPageId());
         outBuffer = store.createData();
     }
@@ -226,6 +231,7 @@ public class PageLog {
         if (stage == RECOVERY_STAGE_ALLOCATE) {
             PageInputStream in = new PageInputStream(store, firstTrunkPage, firstDataPage);
             usedLogPages = in.allocateAllPages();
+            in.close();
             return;
         }
         pageIn = new PageInputStream(store, firstTrunkPage, firstDataPage);
@@ -465,7 +471,7 @@ public class PageLog {
     }
 
     private void flushOut() throws IOException {
-        pageOut.write(outBuffer.getBytes(), 0, outBuffer.length());
+        pageBuffer.write(outBuffer.getBytes(), 0, outBuffer.length());
         outBuffer.reset();
     }
 
@@ -513,6 +519,7 @@ public class PageLog {
             }
             // store it on a separate log page
             int pageSize = store.getPageSize();
+            flushBuffer();
             pageOut.fillPage();
             outBuffer.writeByte((byte) PREPARE_COMMIT);
             outBuffer.writeVarInt(session.getId());
@@ -522,6 +529,7 @@ public class PageLog {
             }
             flushOut();
             // store it on a separate log page
+            flushBuffer();
             pageOut.fillPage();
             if (log.getFlushOnEachCommit()) {
                 flush();
@@ -600,6 +608,7 @@ public class PageLog {
      */
     void flush() throws SQLException {
         try {
+            flushBuffer();
             pageOut.flush();
         } catch (IOException e) {
             throw Message.convertIOException(e, null);
@@ -619,6 +628,7 @@ public class PageLog {
         undo = new BitField();
         logSectionId++;
         logPos = 0;
+        flushBuffer();
         pageOut.fillPage();
         int currentDataPage = pageOut.getCurrentDataPageId();
         logSectionPageMap.put(logSectionId, currentDataPage);
@@ -785,4 +795,12 @@ public class PageLog {
         sessionStates = New.hashMap();
     }
 
+    private void flushBuffer() throws SQLException {
+        try {
+            pageBuffer.flush();
+        } catch (IOException e) {
+            throw Message.convertIOException(e, null);
+        }
+    }
+
 }