[
https://issues.apache.org/jira/browse/TRAFODION-1914?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15289114#comment-15289114
]
liu ming commented on TRAFODION-1914:
-------------------------------------
yes, I see.
It is like 'covered index'. A new syntax should be invented. unique index
cannot support this.
this must be added as a new feature, yes, it makes sense.
thanks,
Ming
> optimize "added columns" in indexes
> -----------------------------------
>
> Key: TRAFODION-1914
> URL: https://issues.apache.org/jira/browse/TRAFODION-1914
> Project: Apache Trafodion
> Issue Type: Improvement
> Components: sql-cmp
> Reporter: Eric Owhadi
>
> the current CREATE INDEX feature will always put each column added to the
> index in the clustering key. But sometimes, users just want to add columns to
> the index to avoid having to probe back the primary table to fetch just one
> or 2 column back. Instead copying these columns in the index can avoid making
> a probe back to main table and therefore improve performance. Current
> implementation allows this, but will always put the extra column as part of
> the clustering key. That is not optimal, and very bad for the case of
> VARCHAR, since they are exploded to there max size when part of the
> clustering key. So this JIRA is abount altering the syntax of create index,
> and flag columns that are added but should not be part of the clustering key.
--
This message was sent by Atlassian JIRA
(v6.3.4#6332)
