[jira] [Updated] (PHOENIX-4717) Document restrictions on adding primary key columns

["Thomas D'Silva (JIRA)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/PHOENIX-4717?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Thomas D'Silva updated PHOENIX-4717:
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    Summary: Document restrictions on adding primary key columns  (was: Document when a primary column is allowed to be added)

> Document restrictions on adding primary key columns
> ---------------------------------------------------
>
>                 Key: PHOENIX-4717
>                 URL: https://issues.apache.org/jira/browse/PHOENIX-4717
>             Project: Phoenix
>          Issue Type: Task
>            Reporter: Thomas D'Silva
>            Priority: Major
>
> For both views and tables
> 1. We allow nullable columns in the PK, but only if they're variable length. Variable length types may be null, since we use a null-byte terminator (which is a disallowed character in variable length types). Fixed width types do not have a way of representing null.
> There is the following TODO in PColumnImpl.init 
> // TODO: we may be able to allow this for columns at the end of the PK
> 2. We disallow adding a column to the PK 
>    a) if the last PK column is VARBINARY 
>    b) if the last PK column is fixed width and nullable //not sure if this is possible currently because of #1
>    c) if the column is not nullable (in order to handle existing rows)
> For views:
> 1. We disallow adding a column to the PK If the last pk column is variable length
> If the last pk column is variable length then we read all the bytes of the rowkey without looking for a separator byte so we cannot add a pk column to a view if the last pk column of the parent is variable length (see https://issues.apache.org/jira/browse/PHOENIX-978?focusedCommentId=14617847&page=com.atlassian.jira.plugin.system.issuetabpanels%3Acomment-tabpanel#comment-14617847)



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