[
https://issues.apache.org/jira/browse/TAJO-838?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14166171#comment-14166171
]
Jihoon Son commented on TAJO-838:
---------------------------------
Hi [~mhthanh], thanks for your comment.
You are right. The index creation and maintenance are also very important. The
index creation time was about 125 seconds.
On the index maintenance, I think that there will be two cases. The first case
is when an index is created for a partitioned table. Since new data are
appended to the partitioned table, we definitely need to support automatic
(implicit) index update for it. This is a remaining issue that must be
resolved. The second case is that a user deletes a table that has an index. In
this case, we also need to remove the index automatically.
Since HDFS is an append-only file system, I'm hard to imagine other cases. If I
miss something, please let me know.
On the index structure, an index provide only pointers to the real data. Data
are not packed inside the index.
Sincerely,
Jihoon
> Improve query planner to utilize index
> --------------------------------------
>
> Key: TAJO-838
> URL: https://issues.apache.org/jira/browse/TAJO-838
> Project: Tajo
> Issue Type: Sub-task
> Components: planner/optimizer
> Reporter: Jihoon Son
> Assignee: Jihoon Son
> Priority: Minor
>
> Index can improve the query performance when the selectivity of query is high.
> Thus, query planner should decide whether index is used or not for a given
> query.
> The selectivity can be guessed using statistics.
--
This message was sent by Atlassian JIRA
(v6.3.4#6332)
