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From "James Taylor (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (PHOENIX-2514) Even with ORDER BY clause the LIMIT does not work correctly with salted tables containing many records.
Date Fri, 11 Dec 2015 06:07:10 GMT

    [ https://issues.apache.org/jira/browse/PHOENIX-2514?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15052243#comment-15052243
] 

James Taylor commented on PHOENIX-2514:
---------------------------------------

We'll need to know the set of rows that leads to this issue to get anywhere with it. If you
could attach a set of UPERT VALUE calls or even a CSV of the minimal set of data for which
this occurs, that would be much appreciated, [~sumit.nigam].

> Even with ORDER BY clause the LIMIT does not work correctly with salted tables containing
many records.
> -------------------------------------------------------------------------------------------------------
>
>                 Key: PHOENIX-2514
>                 URL: https://issues.apache.org/jira/browse/PHOENIX-2514
>             Project: Phoenix
>          Issue Type: Bug
>    Affects Versions: 4.5.1
>         Environment: HBase-0.98.14
>            Reporter: Sumit Nigam
>            Priority: Critical
>              Labels: LIMIT, hbase, phoenix, salted
>             Fix For: 4.5.1
>
>
> A query such as SELECT CURRENT_TIMESTAMP FROM TBL ORDER BY CURRENT_TIMESTAMP DESC LIMIT
1 does not really return the MAX(CURRENT_TIMESTAMP). The table is salted and has 200272 records.
> select current_timestamp from TBL order by current_timestamp desc limit 1;
> +------------------------------------------+
> |            CURRENT_TIMESTAMP    |
> +------------------------------------------+
> | 1448815328556                            |
> +------------------------------------------+
> select max(current_timestamp) from TBL;
> +------------------------------------------+
> |         MAX("CURRENT_TIMESTAMP")         |
> +------------------------------------------+
> | 1449732792090                            |
> +------------------------------------------+
> The results are different. MAX is of course, returning the right record.
> The above query is one example. There are other queries which also seem to be returning
incorrect record with ORDER BY and LIMIT.
> Is this also correct that when there is a WHERE clause limiting the number of projected
records, then LIMIT seems to work fine? I seem to be noticing that also.
> The table DDL is:
> CREATE TABLE IF NOT EXISTS TBL 
> (CURRENT_TIMESTAMP BIGINT NOT NULL, ID VARCHAR(96), CURR_EXDOC VARCHAR,  CURR_CHECKSUM
VARCHAR(32), SUMMARY VARCHAR, 
> CONSTRAINT PK PRIMARY KEY(CURRENT_TIMESTAMP, ID)) 
> BLOCKCACHE=FALSE, COMPRESSION=SNAPPY, SALT_BUCKETS=8



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