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https://issues.apache.org/jira/browse/PHOENIX-4845?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16681875#comment-16681875
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James Taylor commented on PHOENIX-4845:
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{quote}[~dbwong] points out that the result of INVERT is not known unless you
the schema, whereas DESC is clear from looking at just the query. And I very
much agree.
{quote}
INVERT is a built-in function and doesn't require a language change. It's
semantics are clear - invert the bits of the value. We could have a different
name for this built in function, like REVERSE if folks think that's more clear.
It's not clear what DESC(x) is nor what it's semantics are. What would it do if
x is not descending? On top of that, DESC is a keyword.
If INVERT doesn't have the impact we want, then we should file a bug and fix it
IMHO.
Using \{{phoenix.query.force.rowkeyorder}} has other negative performance
implications (i.e. introducing extra merge sorts where they're otherwise not
necessary), so I'd rather not conflate it with this.
> Support using Row Value Constructors in OFFSET clause to support paging in
> tables where the sort order of PK columns varies
> ---------------------------------------------------------------------------------------------------------------------------
>
> Key: PHOENIX-4845
> URL: https://issues.apache.org/jira/browse/PHOENIX-4845
> Project: Phoenix
> Issue Type: New Feature
> Reporter: Thomas D'Silva
> Priority: Major
> Labels: DESC, SFDC
> Attachments: PHOENIX-offset.txt
>
>
> RVCs along with the LIMIT clause are useful for efficiently paging through
> rows (see [http://phoenix.apache.org/paged.html]). This works well if the pk
> columns are sorted ascending, we can always use the > operator to query for
> the next batch of row.
> However if the PK of a table is (A DESC, B DESC) we cannot use the following
> query to page through the data
> {code:java}
> SELECT * FROM TABLE WHERE (A, B) > (?, ?) ORDER BY A DESC, B DESC LIMIT 20
> {code}
> Since the rows are sorted by A desc and then by B descending we need change
> the comparison order
> {code:java}
> SELECT * FROM TABLE WHERE (A, B) < (?, ?) ORDER BY A DESC, B DESC LIMIT 20
> {code}
> If the PK of a table contains columns with mixed sort order for eg (A DESC,
> B) then we cannot use RVC to page through data.
> If we supported using RVCs in the offset clause we could use the offset to
> set the start row of the scan. Clients would not have to have logic to
> determine the comparison operator. This would also support paging through
> data for tables where the PK columns are sorted in mixed order.
> {code:java}
> SELECT * FROM TABLE ORDER BY A DESC, B LIMIT 20 OFFSET (?,?)
> {code}
> We would only allow using the offset if the rows are ordered by the sort
> order of the PK columns.
>
> FYI [~jfernando_sfdc]
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