write parquet with statistics min max with binary field

[Stephen Joung]

Hi, I am trying to use spark sql filter push down. and specially want to
use row group skipping with parquet file.

And I guessed that I need parquet file with statistics min/max.

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On spark master branch - I tried to write single column with "a", "b", "c"
to parquet file f1

   scala> List("a", "b", "c").toDF("field1").coalesce(1).write.parquet("f1")

But saved file does not have statistics (min, max)

   $ ls f1/*.parquet
   f1/part-00000-445036f9-7a40-4333-8405-8451faa44319-c000.snappy.parquet
   $ parquet-tool meta  f1/*.parquet
   file:
 file:/Users/stephen/p/spark/f1/part-00000-445036f9-7a40-4333-8405-8451faa44319-
c000.snappy.parquet
   creator:     parquet-mr version 1.8.2 (build
c6522788629e590a53eb79874b95f6c3ff11f16c)
   extra:       org.apache.spark.sql.parquet.row.metadata =
{"type":"struct","fields":[{"name":"field1","type":"string","nullable":true,"metadata":{}}]}

   file schema: spark_schema

 
--------------------------------------------------------------------------------
   field1:      OPTIONAL BINARY O:UTF8 R:0 D:1

   row group 1: RC:3 TS:48 OFFSET:4

 
--------------------------------------------------------------------------------
   field1:       BINARY SNAPPY DO:0 FPO:4 SZ:50/48/0.96 VC:3
ENC:BIT_PACKED,RLE,PLAIN ST:[no stats for this column]

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Any pointer or comment would be appreciated.
Thank you.