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https://issues.apache.org/jira/browse/IMPALA-11168?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Zoltán Borók-Nagy updated IMPALA-11168:
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Description:
Hive supports a few pseudo-columns (virtual column):
[https://cwiki.apache.org/confluence/display/hive/languagemanual+virtualcolumns]
It would be useful to add support for a few pseudo-columns for Impala as well.
E.g. to implement support for Iceberg position-based deletes we'd need the file
name and ordinal position for each row.
Hive has {{INPUT_\_FILE_\_NAME}} which returns full URI of the data file.
Unfortunately it doesn't have a pseudo-column for the ordinal position of rows.
So we need to introduce a new pseudo-column for that, probably with the name
{{ORDINAL_\_POSITION_\_INSIDE_\_FILE}}, or stg. like that.
was:
Hive supports a few pseudo-columns (virtual column):
[https://cwiki.apache.org/confluence/display/hive/languagemanual+virtualcolumns]
It would be useful to add support for a few pseudo-columns for Impala as well.
E.g. to implement support for Iceberg position-based deletes we'd need the file
name and ordinal position for each row.
Hive has {{INPUT__FILE__NAME}} which returns full URI of the data file.
Unfortunately it doesn't have a pseudo-column for the ordinal position of rows.
So we need to introduce a new pseudo-column for that, probably with the name
{{{}ORDINAL__POSITION__INSIDE__FILE{}}}, or stg. like that.
> Add pseudo-columns for Impala
> -----------------------------
>
> Key: IMPALA-11168
> URL: https://issues.apache.org/jira/browse/IMPALA-11168
> Project: IMPALA
> Issue Type: New Feature
> Components: Backend, Frontend
> Reporter: Zoltán Borók-Nagy
> Priority: Major
>
> Hive supports a few pseudo-columns (virtual column):
> [https://cwiki.apache.org/confluence/display/hive/languagemanual+virtualcolumns]
> It would be useful to add support for a few pseudo-columns for Impala as well.
> E.g. to implement support for Iceberg position-based deletes we'd need the
> file name and ordinal position for each row.
> Hive has {{INPUT_\_FILE_\_NAME}} which returns full URI of the data file.
> Unfortunately it doesn't have a pseudo-column for the ordinal position of
> rows. So we need to introduce a new pseudo-column for that, probably with the
> name {{ORDINAL_\_POSITION_\_INSIDE_\_FILE}}, or stg. like that.
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