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https://issues.apache.org/jira/browse/PHOENIX-258?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15310636#comment-15310636
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James Taylor commented on PHOENIX-258:
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Yes, good point, [~lhofhansl]. The reverse scan case is tricky. Padding with a
single 0xFF isn't necessarily enough, as if the next field is a BIGINT, you'd
need 8 0xFF bytes, and if the field after that is an INTEGER, you'd need 4 more
0xFF bytes. Since we have the schema information, we can compute the necessary
padding in the constructor. You'd just loop through the fields in the
RowKeySchema and add the field.getByteSize() while field.isFixedLength() is
true. Then add one more to the sum you get and you'll be good in all cases.
> Use skip scan when SELECT DISTINCT on leading row key column(s)
> ---------------------------------------------------------------
>
> Key: PHOENIX-258
> URL: https://issues.apache.org/jira/browse/PHOENIX-258
> Project: Phoenix
> Issue Type: Task
> Reporter: ryang-sfdc
> Assignee: Lars Hofhansl
> Fix For: 4.8.0
>
> Attachments: 258-WIP.txt, 258-v1.txt, 258-v10.txt, 258-v11.txt,
> 258-v12.txt, 258-v13.txt, 258-v14.txt, 258-v2.txt, 258-v3.txt, 258-v4.txt,
> 258-v5.txt, 258-v6.txt, 258-v7.txt, 258-v8.txt, 258-v9.txt, 258.txt,
> DistinctFixedPrefixFilter.java, in-clause.png
>
>
> create table(a varchar(32) not null, date date not null constraint pk primary
> key(a,date))
> [["PLAN"],["CLIENT PARALLEL 94-WAY FULL SCAN OVER foo"],[" SERVER
> AGGREGATE INTO ORDERED DISTINCT ROWS BY [a]"],["CLIENT MERGE SORT"]]
>
> We should skip scan.
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