title: TimescaleDB slower than plain postgresql 10 for insert
body: <p>I am inserting 1m rows into a test table with timescale using JDBC and the performance seems to be about half that of plain postgresql. Timescale tuning was done by taking all values suggested by the timescale-tune utility. What am I doing wrong?</p>
  
  <pre><code>   private static void writeTable(String sql, int count, int commitCount,
     Connection conn) throws Exception
     {
         conn.setAutoCommit(false);
         long start = System.currentTimeMillis();
         long t = start;
         PreparedStatement stmt = conn.prepareStatement(sql);
         for(int i = 0; i &lt; count; i++)
         {
             stmt.setTimestamp(1, new Timestamp(t));
             stmt.setDouble(2, 10.9);
             stmt.addBatch();
             t ++;
             if(commitCount != -1 &amp;&amp; ((i + 1) % commitCount) == 0)
             {
                 stmt.executeBatch();
                 conn.commit();
             }
         }
         stmt.executeBatch();
         stmt.close();
         conn.commit();
         conn.close();
         long diff = System.currentTimeMillis() - start;
         System.out.println("Count      : " + count);
         System.out.println("Total Time : " + diff);
         System.out.println("Writes/Sec : " + ((count * 1000) / diff));
     }
  </code></pre>
  
  <pre><code>Query: INSERT INTO kt_device_info (di_device_id, di_time, di_value) VALUES (1,?,?)
  </code></pre>
  
  <pre><code>Table:
  CREATE TABLE kt_device (
      id              BIGINT PRIMARY KEY,
      d_name          TEXT
  );
  
  insert into kt_device(id, d_name) values (1, 'dev-1');
  
  CREATE TABLE kt_device_info (
      di_device_id    BIGINT REFERENCES  kt_device NOT NULL,
      di_time         TIMESTAMPTZ NOT NULL,
      di_value        DOUBLE PRECISION  NULL
  );
  
  SELECT create_hypertable('kt_device_info', 'di_time');
  </code></pre>
  
  <p><strong>Timescale</strong> :
  Count      : 1000000
  Total Time : 42026
  <strong>Writes/Sec : 23794</strong></p>
  
  <p><strong>Postgres 10:</strong>
  Count      : 1000000
  Total Time : 22573
  <strong>Writes/Sec : 44300</strong></p>
  
  <p>PostgreSQL 10.10 (Ubuntu 10.10-1.pgdg16.04+1) on x86_64-pc-linux-gnu, compiled by gcc (Ubuntu 5.4.0-6ubuntu1~16.04.11) 5.4.0 20160609, 64-bit</p>
  
  <p>timescaledb | 1.4.2   | public | Enables scalable inserts and complex queries for time-series data</p>
  
  <p>Hardware:
  Intel(R) Core(TM) i7-4702MQ CPU @ 2.20GHz, 16GB Memory</p>
  
  <pre><code>Chunks:
  SELECT show_chunks('kt_device_info');
                show_chunks               
  ----------------------------------------
   _timescaledb_internal._hyper_7_7_chunk
  (1 row)
  </code></pre>