[jira] [Resolved] (PHOENIX-654) Minimize projection into scan for VIEW

["James Taylor (JIRA)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/PHOENIX-654?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

James Taylor resolved PHOENIX-654.
----------------------------------
       Resolution: Duplicate
    Fix Version/s: 4.7.0

Fixed as part of PHOENIX-1312

> Minimize projection into scan for VIEW
> --------------------------------------
>
>                 Key: PHOENIX-654
>                 URL: https://issues.apache.org/jira/browse/PHOENIX-654
>             Project: Phoenix
>          Issue Type: Sub-task
>            Reporter: James Taylor
>             Fix For: 4.7.0
>
>
> When you create a TABLE, we insert an empty key value into the first column family that we can count on being there for every row. For a VIEW, we don't do that, so we just fall back on projecting everything into a scan. If there are lots of columns (for example, 60,000 in [this](https://groups.google.com/forum/_!topic/phoenix-hbase-user/JgQjlqC4-uw) case), the scan is very slow.
> Instead, we should only project everything when absolutely necessary, in these cases:
>    * IS NULL expression
>    * CASE WHEN with an ELSE expression
>    * Usages of row value constructor
> * When a column in the primary key is used
> * When there is no where clause
> * When there is a group by of a nullable expression
> We could potentially do the same for a TABLE, but the empty key value seems like a better trade off as far as performance goes. In addition, we need the empty key value as a row cannot exist without at least one key value, making it impossible to support use cases that only define a primary key.



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