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https://issues.apache.org/jira/browse/DRILL-4264?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16086146#comment-16086146
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Volodymyr Vysotskyi commented on DRILL-4264:
--------------------------------------------
Drill handles field names and schema paths in different ways. For schema paths
Drill uses Calcite. The required schema is returned by the method
[getSchema()|https://github.com/mapr/incubator-calcite/blob/DrillCalcite1.4.0-mapr-1.4.0/core/src/main/java/org/apache/calcite/prepare/CalciteCatalogReader.java#L157].
So for the input {{`dfs.data`}} needful chema will be returned from the first
iteration of the cycle. For the case {{dfs.data}} in the first iteration will
be assigned schema {{dfs}} and in the next iteration schema {{data}}.
Query
{code:sql}
SELECT `rk.q`, `m.a.b` FROM test_table;
{code}
returns
{noformat}
---------------------------------------------------------------------------------------------------------
| rk.q<VARCHAR(OPTIONAL)> | m.a.b<INT(OPTIONAL)>
|
---------------------------------------------------------------------------------------------------------
| a | null
|
---------------------------------------------------------------------------------------------------------
{noformat}
For this case Drill is looking for the field with name {{m.a.b}}.
Query
{code:sql}
SELECT t.`rk.q`, t.m.`a.b` FROM test_table t;
{code}
returns correct result:
{noformat}
---------------------------------------------------------------------------------------------------------
| rk.q<VARCHAR(OPTIONAL)> | EXPR$1<VARCHAR(OPTIONAL)>
|
---------------------------------------------------------------------------------------------------------
| a | 1
|
---------------------------------------------------------------------------------------------------------
{noformat}
So yes, dot inside backticks is considered as a part of the field name and
outside is considered as a separator.
> Dots in identifier are not escaped correctly
> --------------------------------------------
>
> Key: DRILL-4264
> URL: https://issues.apache.org/jira/browse/DRILL-4264
> Project: Apache Drill
> Issue Type: Bug
> Components: Execution - Codegen
> Reporter: Alex
> Assignee: Volodymyr Vysotskyi
>
> If you have some json data like this...
> {code:javascript}
> {
> "0.0.1":{
> "version":"0.0.1",
> "date_created":"2014-03-15"
> },
> "0.1.2":{
> "version":"0.1.2",
> "date_created":"2014-05-21"
> }
> }
> {code}
> ... there is no way to select any of the rows since their identifiers contain
> dots and when trying to select them, Drill throws the following error:
> Error: SYSTEM ERROR: UnsupportedOperationException: Unhandled field reference
> "0.0.1"; a field reference identifier must not have the form of a qualified
> name
> This must be fixed since there are many json data files containing dots in
> some of the keys (e.g. when specifying version numbers etc)
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