title: parquet too many row groups than expected in the file
body: <p>I'm currently writing parquet with map reduce, I config my row group size to be 256M, and hdfs block size to be 256M as well. The output file size is around 1G per file.</p>
  
  <p>So I should expected 4 row groups in the generated file. But when I use:</p>
  
  <p><code>parquet-tools meta path/to/my/file | grep "row group"</code></p>
  
  <p>It gives me 63 row groups with different size and row count:</p>
  
  <pre><code>row group 1:                      RC:69816 TS:244168913
  row group 2:                      RC:35111 TS:117407826
  row group 3:                      RC:18488 TS:60107388
  row group 4:                      RC:10357 TS:33260415
  row group 5:                      RC:7905 TS:24956045
  row group 6:                      RC:4754 TS:15149122
  row group 7:                      RC:3862 TS:12476651
  row group 8:                      RC:2738 TS:9001631
  row group 9:                      RC:2104 TS:7120040
  row group 10:                     RC:1910 TS:6398391
  row group 11:                     RC:1508 TS:5219072
  row group 12:                     RC:1386 TS:4676154
  row group 13:                     RC:1124 TS:3950635
  row group 14:                     RC:999 TS:3518545
  row group 15:                     RC:865 TS:3121657
  row group 16:                     RC:774 TS:2801614
  row group 17:                     RC:678 TS:2490904
  row group 18:                     RC:511 TS:1996167
  row group 19:                     RC:69808 TS:243894989
  row group 20:                     RC:30176 TS:99585195
  row group 21:                     RC:20678 TS:67779524
  row group 22:                     RC:10743 TS:34547874
  row group 23:                     RC:8258 TS:26080110
  row group 24:                     RC:5227 TS:16456577
  row group 25:                     RC:4136 TS:13321721
  row group 26:                     RC:3207 TS:10272043
  row group 27:                     RC:2437 TS:8107932
  row group 28:                     RC:1945 TS:6563867
  row group 29:                     RC:1561 TS:5320028
  row group 30:                     RC:1389 TS:4809485
  row group 31:                     RC:1206 TS:4251584
  row group 32:                     RC:996 TS:3581746
  row group 33:                     RC:895 TS:3203224
  row group 34:                     RC:757 TS:2869939
  row group 35:                     RC:653 TS:2550716
  row group 36:                     RC:531 TS:2008746
  row group 37:                     RC:69706 TS:244420245
  row group 38:                     RC:32703 TS:109391929
  row group 39:                     RC:18640 TS:60918458
  row group 40:                     RC:10737 TS:34272225
  row group 41:                     RC:7812 TS:24814707
  row group 42:                     RC:5176 TS:16206655
  row group 43:                     RC:4123 TS:13224377
  row group 44:                     RC:3391 TS:10946649
  row group 45:                     RC:2138 TS:7248145
  row group 46:                     RC:1960 TS:6566944
  row group 47:                     RC:1538 TS:5294523
  row group 48:                     RC:1355 TS:4744634
  row group 49:                     RC:1225 TS:4194625
  row group 50:                     RC:1026 TS:3587484
  row group 51:                     RC:877 TS:3134267
  row group 52:                     RC:785 TS:2846718
  row group 53:                     RC:675 TS:2546836
  row group 54:                     RC:538 TS:2016450
  row group 55:                     RC:69762 TS:244915809
  row group 56:                     RC:32390 TS:108310300
  row group 57:                     RC:18095 TS:58754777
  row group 58:                     RC:10759 TS:34405301
  row group 59:                     RC:8195 TS:26029310
  row group 60:                     RC:5286 TS:16597963
  row group 61:                     RC:4231 TS:13415076
  row group 62:                     RC:3538 TS:11465640
  row group 63:                     RC:135 TS:688850
  </code></pre>
  
  <p>There is a recursive pattern for the row group, anyone know why parquet does not honor my configured row group size (256M) ? </p>