I created a parquet file using Drill, but date values in the parquet files
don’t appear to be a logical INT32 type and as such when I’m trying to read the
parquet file in Spark it looks corrupted..
Here’s my test case..
A. Create a test.txt file in /tmp:
as_of
2016-09-30
B. Convert it to parquet using Drill:
0: jdbc:drill:zk=local> create table dfs.tmp.`/test` as select cast(as_of AS
date) as as_of from table(dfs.`/tmp/test.txt`(type => 'text', fieldDelimiter =>
',', extractHeader => true));
C. Read the new file using Drill which looks fine:
0: jdbc:drill:zk=local> select * from dfs.`/tmp/test`;
+-------------+
| as_of |
+-------------+
| 2016-09-30 |
+-------------+
D. However running parquet-tools on it gives a completely different result:
java -jar parquet-tools-1.6.1-SNAPSHOT.jar head -n3 /tmp/test
as_of = 4898250
java -jar parquet-tools-1.6.1-SNAPSHOT.jar schema /tmp/test/0_0_0.parquet
message root {
required int32 as_of (DATE);
}
According to the Parquet docs.. 4898250 days after Jan 1st 1970 is sometime in
the year 15,435..
https://github.com/Parquet/parquet-format/blob/master/LogicalTypes.md
DATE
DATE is used to for a logical date type, without a time of day. It must
annotate an int32 that stores the number of days from the Unix epoch, 1 January
1970.
David Lee
Vice President | BlackRock
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