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https://issues.apache.org/jira/browse/DRILL-4694?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15316777#comment-15316777
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ASF GitHub Bot commented on DRILL-4694:
---------------------------------------
Github user parthchandra commented on a diff in the pull request:
https://github.com/apache/drill/pull/514#discussion_r65928727
--- Diff:
exec/java-exec/src/main/codegen/templates/JsonOutputRecordWriter.java ---
@@ -61,7 +62,13 @@
@Override
public void startField() throws IOException {
+ <#if mode.prefix = "Nullable" >
--- End diff --
Dumb mistake. Thanks for catching it!
> CTAS in JSON format produces extraneous NULL fields
> ---------------------------------------------------
>
> Key: DRILL-4694
> URL: https://issues.apache.org/jira/browse/DRILL-4694
> Project: Apache Drill
> Issue Type: Bug
> Components: Storage - JSON
> Affects Versions: 1.6.0
> Reporter: Aman Sinha
> Assignee: Aman Sinha
>
> Consider the following JSON file:
> {noformat}
> // file t2.json
> {
> "X" : {
> "key1" : "value1",
> "key2" : "value2"
> }
> }
> {
> "X" : {
> "key3" : "value3",
> "key4" : "value4"
> }
> }
> {
> "X" : {
> "key5" : "value5",
> "key6" : "value6"
> }
> }
> {noformat}
> Now create a table in Json format using CTAS:
> {noformat}
> 0: jdbc:drill:zk=local> alter session set `store.format` = 'json';
> 0: jdbc:drill:zk=local> create table dfs.tmp.jt12 as select t.`X` from
> `t2.json` t;
> +-----------+----------------------------+
> | Fragment | Number of records written |
> +-----------+----------------------------+
> | 0_0 | 3 |
> +-----------+----------------------------+
> {noformat}
> The output file has rows with union schema of all the fields in all the
> records. This creates extraneous Null fields in the output:
> {noformat}
> $ cat jt12/0_0_0.json
> {
> "X" : {
> "key1" : "value1",
> "key2" : "value2",
> "key3" : null,
> "key4" : null,
> "key5" : null,
> "key6" : null
> }
> } {
> "X" : {
> "key1" : null,
> "key2" : null,
> "key3" : "value3",
> "key4" : "value4",
> "key5" : null,
> "key6" : null
> }
> } {
> "X" : {
> "key1" : null,
> "key2" : null,
> "key3" : null,
> "key4" : null,
> "key5" : "value5",
> "key6" : "value6"
> }
> }
> {noformat}
> Note that if I change the output format to CSV or Parquet, there are no Null
> fields created in the output file. The expectation for a CTAS in json
> format is that the output should match that of the input json data.
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