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https://issues.apache.org/jira/browse/HIVE-27726?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17768570#comment-17768570
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Stamatis Zampetakis commented on HIVE-27726:
--------------------------------------------
HIVE-19770 and HIVE-27399 showcase some examples where enhanced constant
folding led to "missing lineage" information.
> No lineage for constant literals
> --------------------------------
>
> Key: HIVE-27726
> URL: https://issues.apache.org/jira/browse/HIVE-27726
> Project: Hive
> Issue Type: Improvement
> Components: HiveServer2
> Affects Versions: 4.0.0-beta-1
> Reporter: Stamatis Zampetakis
> Priority: Minor
>
> Consider the following statement where we create a table based on another
> table and some constant expressions/literals.
> {code:java}
> CREATE TABLE tbl1 AS (SELECT 'Bob', 'Alice', key, value || 'some' FROM src)
> {code}
> Observe that column 0, and column 1 of tbl1 originate from constant literals.
> Currently (commit e5a7ce2f091da1f8a324da6e489cda59b9e4bfc6), there is no
> lineage information for columns originating from constants.
> The {{org.apache.hadoop.hive.ql.hooks.LineageLogger}} will display the
> following the aforementioned DDL statement.
>
> {noformat}
> POSTHOOK: Lineage: tbl1._c0 SIMPLE []
> POSTHOOK: Lineage: tbl1._c1 SIMPLE []
> POSTHOOK: Lineage: tbl1._c3 EXPRESSION [(src)src.FieldSchema(name:value,
> type:string, comment:default), ]
> POSTHOOK: Lineage: tbl1.key SIMPLE [(src)src.FieldSchema(name:key,
> type:string, comment:default), ]
> {noformat}
> This is not really a bug since we cannot really say that something is broken
> but maybe there is a way to reflect that {{c0}} and {{c1}} originate from
> constants to avoid the misconception that lineage is missing.
> Note, that constant folding may also lead to the same behavior since
> expressions may be simplified to constants and the latter do not appear in
> the lineage output.
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