Derby
  1. Derby
  2. DERBY-3753

select from table with integer primary key and blob column does not do sort avoidance

    Details

    • Type: Bug Bug
    • Status: Open
    • Priority: Major Major
    • Resolution: Unresolved
    • Affects Version/s: 10.3.3.0, 10.4.1.3, 10.5.1.1
    • Fix Version/s: None
    • Component/s: SQL
    • Urgency:
      Normal
    • Issue & fix info:
      High Value Fix, Repro attached

      Description

      In working on DERBY-3732 I noticed that select from a table with a primary key and a blob column does not do sort avoidance. If you remove the optimizer directive, this fixture in BlobMemTest will run out of memory sorting if memory.BlobMemTest is run with 16M heap.

      private void testBlobLength(boolean lengthless) throws SQLException, IOException, IllegalArgumentException, IllegalAccessException, InvocationTargetException {
      getConnection().setAutoCommit(false);
      Statement s = createStatement();
      s.executeUpdate("CREATE TABLE BLOBTAB (K INT CONSTRAINT PK PRIMARY KEY, B BLOB(" + LONG_BLOB_LENGTH + "))");

      PreparedStatement ps = prepareStatement("INSERT INTO BLOBTAB VALUES(?,?)");
      // We allocate 16MB for the test so use something bigger than that.
      ps.setInt(1,1);
      LoopingAlphabetStream stream = new LoopingAlphabetStream(LONG_BLOB_LENGTH);
      if (lengthless) {
      Method m = null;
      try {
      Class c = ps.getClass();
      m = c.getMethod("setBinaryStream",new Class[]

      {Integer.TYPE, InputStream.class}

      );
      } catch (NoSuchMethodException e)

      { // ignore method not found as method may not be present for // jdk's lower than 1.6. println("Skipping lengthless insert because method is not available"); return; }

      m.invoke(ps, new Object[]

      {new Integer(2),stream}

      );
      }
      else
      ps.setBinaryStream(2, stream,LONG_BLOB_LENGTH);
      ps.executeUpdate();
      // insert a zero length blob.
      ps.setInt(1, 2);
      ps.setBytes(2, new byte[] {});
      ps.executeUpdate();
      // insert a null blob.
      ps.setInt(1, 3);
      ps.setBytes(2,null);
      ps.executeUpdate();
      // insert a short blob
      ps.setInt(1, 4);
      ps.setBytes(2, SHORT_BLOB_BYTES);
      ps.executeUpdate();
      // Currently need to use optimizer override to force use of the index.
      // Derby should use sort avoidance and do it automatically, but there
      // appears to be a bug.
      ResultSet rs = s.executeQuery("SELECT K, LENGTH(B), B FROM BLOBTAB" +
      "-- DERBY-PROPERTIES constraint=pk\n ORDER BY K");
      rs.next();
      assertEquals(LONG_BLOB_LENGTH_STRING,rs.getString(2));
      // make sure we can still access the blob after getting length.
      // It should be ok because we reset the stream
      InputStream rsstream = rs.getBinaryStream(3);
      int len= 0;
      byte[] buf = new byte[32672];
      for (;

      { int size = rsstream.read(buf); if (size == -1) break; len += size; int expectedValue = ((len -1) % 26) + 'a'; if (size != 0) assertEquals(expectedValue,buf[size -1]); }

      assertEquals(LONG_BLOB_LENGTH,len);
      // empty blob
      rs.next();
      assertEquals("0",rs.getString(2));
      byte[] bytes = rs.getBytes(3);
      assertEquals(0, bytes.length);
      // null blob
      rs.next();
      assertEquals(null,rs.getString(2));
      bytes = rs.getBytes(3);
      assertEquals(null,bytes);
      // short blob
      rs.next();
      assertEquals("3",rs.getString(2));
      bytes = rs.getBytes(3);
      assertTrue(Arrays.equals(SHORT_BLOB_BYTES, bytes));
      rs.close();

      // Select just length without selecting the blob.
      rs = s.executeQuery("SELECT K, LENGTH(B) FROM BLOBTAB " +
      "ORDER BY K");
      JDBC.assertFullResultSet(rs, new String [][] {{"1",LONG_BLOB_LENGTH_STRING},

      {"2","0"}

      ,

      {"3",null}

      ,{"4","3"}});
      }

      1. derby.log
        6 kB
        Kathey Marsden
      2. Derby3753.java
        1 kB
        Kathey Marsden

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            • Assignee:
              Unassigned
              Reporter:
              Kathey Marsden
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              Dates

              • Created:
                Updated:

                Development