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https://issues.apache.org/jira/browse/PHOENIX-3941?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16739127#comment-16739127
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Lars Hofhansl edited comment on PHOENIX-3941 at 1/10/19 7:04 AM:
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Perhaps I am missing something here.
>From the examples in the test it seems that this assumes that pk columns of
>the table are included in the index.
I.e. if the table's pk is (A, B, C), and also has a column D, that this prunes
regions only if the index itself contains a prefix of the pk, i.e. the index
would need to defined as ON table(A,D).
This is not necessary, right? We can *always* prune regions based on the prefix
of the PK, no?
I.e. in the above example if the index was defined ON table(D) only, and we now
have a query
WHERE D = x, and A = b; we can still use A = b to prune the regions? Why does
the A need to included in the index?! That seems like a bug.
was (Author: lhofhansl):
Perhaps I am missing something here.
>From the examples in the test it seems that this assumes that pk columns of
>the table are included in the index.
I.e. if the table's pk is (A, B, C), and also has a column D, that this prunes
regions only if the index itself contains a prefix of the pk, i.e. the index
would need to defined as ON table(A,D).
This is not necessary, right? We can *always* prune regions based on the prefix
of the PK, no?
I.e. in the above example if the index was define ON table(D) only, and we now
have a query
WHERE D = x, and A = b; we can still use A = b to prune the regions? Why does
the A need to included in the index?! That seems like a bug.
> Filter regions to scan for local indexes based on data table leading pk
> filter conditions
> -----------------------------------------------------------------------------------------
>
> Key: PHOENIX-3941
> URL: https://issues.apache.org/jira/browse/PHOENIX-3941
> Project: Phoenix
> Issue Type: Improvement
> Reporter: James Taylor
> Assignee: James Taylor
> Priority: Major
> Labels: SFDC, localIndex
> Fix For: 4.14.0, 5.0.0
>
> Attachments: PHOENIX-3941_v1.patch, PHOENIX-3941_v2.patch,
> PHOENIX-3941_v3.patch, PHOENIX-3941_v4.patch
>
>
> Had a good offline conversation with [~ndimiduk] at PhoenixCon about local
> indexes. Depending on the query, we can often times prune the regions we need
> to scan over based on the where conditions against the data table pk. For
> example, with a multi-tenant table, we only need to scan the regions that are
> prefixed by the tenant ID.
> We can easily get this information from the compilation of the query against
> the data table (which we always do), through the
> statementContext.getScanRanges() structure. We'd just want to keep a pointer
> to the data table QueryPlan from the local index QueryPlan.
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