phoenix-dev mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From "James Taylor (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (PHOENIX-4550) Ensure storage is dense when base table has many views
Date Thu, 25 Jan 2018 20:25:00 GMT

    [ https://issues.apache.org/jira/browse/PHOENIX-4550?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16339821#comment-16339821
] 

James Taylor commented on PHOENIX-4550:
---------------------------------------

I'm still thinking that having a MAX_COLUMNS declaration to preallocate columns plus tracking
the first column encoding at each level would solve our current use case and be pretty easy
to implement. It could be part of the SINGLE_CELL_ARRAY_WITH_OFFSETS format.

I do like the SINGLE_CELL_PER_LEVEL idea, but the scope is quite a bit larger.

WDYT, [~tdsilva]?

> Ensure storage is dense when base table has many views
> ------------------------------------------------------
>
>                 Key: PHOENIX-4550
>                 URL: https://issues.apache.org/jira/browse/PHOENIX-4550
>             Project: Phoenix
>          Issue Type: Improvement
>            Reporter: James Taylor
>            Priority: Major
>
> By declaring the max number of columns on a base table, we can optimize the storage for
SINGLE_CELL_ARRAY_WITH_OFFSETS by not storing null values for the columns preceding the initial
column of a view. This will make a huge difference in storage when you have a base table with
many views. For example:
> {code}
> -- Declare that the base table will have no more than 10 columns
> CREATE IMMUTABLE TABLE base (k1 VARCHAR, prefix CHAR(3) v1 DATE,
>     CONSTRAINT pk PRIMARY KEY (k1, prefix))
>     MULTI_TENANT = true,
>     MAX_COLUMNS = 10;
> CREATE VIEW v1(k2 VARCHAR PRIMARY KEY, v2 VARCHAR, v3 VARCHAR)
>     AS SELECT * FROM base WHERE prefix = 'A00';
> CREATE VIEW v2(k2 VARCHAR PRIMARY KEY, v2 VARCHAR, v3 VARCHAR);
>     AS SELECT * FROM base WHERE prefix = 'A10';
> ...
> {code}
> As the number of views grow, the difference between the base table column encoding (column
#1) and the starting column number of the view (since the starting offset is determined by
an incrementing value on the base table) will increase. This bloats the storage as we need
to store null values for column encodings between the base table column and the starting column
of the view.
> Instead, we'll pass through the MAX_COLUMNS value for queries and anything column encoding
less than this we know it'll be at the start. Anything greater and we'll start the search
from <column encoding> - <minimum view column encoding>.



--
This message was sent by Atlassian JIRA
(v7.6.3#76005)

Mime
View raw message