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https://issues.apache.org/jira/browse/KUDU-1363?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15240323#comment-15240323
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Dan Burkert commented on KUDU-1363:
-----------------------------------
Hi Sameer,
That's correct. The basic steps for adding a new predicate type are:
1) On the c++ side add the predicate type to the kudu::ColumnPredicate class in
column_predicate.h/cc. This includes updating Merge and Evaluate to work with
the new predicate type. You will also need to update some of the scan
optimization logic in scan_spec.cc to account for the new predicate type, and
the partition pruning logic in partition_pruner.cc.
2) Add the new predicate type to the ColumnPredicatePB message.
3) Expose the predicate type in the public API (KuduPredicate in
scan_predicate.h)
4) Add the predicate type to the Java client in the KuduPredicate class.
Note that if the goal is to have a multi-get API for retrieving multiple rows
where you know the primary key for each, an IN predicate will be quite
inefficient (it will require a full table scan). We have discussed a multi-get
API in the past, and would definitely be open to contributions on this problem
as well.
> Add Multiple column range predicates for the same column in a single scan
> -------------------------------------------------------------------------
>
> Key: KUDU-1363
> URL: https://issues.apache.org/jira/browse/KUDU-1363
> Project: Kudu
> Issue Type: New Feature
> Reporter: Chris George
>
> Currently adding multiple column range predicates for the same column does
> essentially an AND between the two predicates which will cause no results to
> be returned.
> This would greatly increase performance were I can complete in one scan what
> would otherwise take two.
> As an example using the java api:
> ColumnRangePredicate columnRangePredicateColumnNameA = new
> ColumnRangePredicate(new ColumnSchema.ColumnSchemaBuilder("column_name",
> Type.STRING).build());
> columnRangePredicateColumnNameA.setLowerBound("A");
> columnRangePredicateColumnNameA.setUpperBound("A");
> ColumnRangePredicate columnRangePredicateColumnNameB = new
> ColumnRangePredicate(new ColumnSchema.ColumnSchemaBuilder("column_name",
> Type.STRING).build());
> columnRangePredicateColumnNameB.setLowerBound("B");
> columnRangePredicateColumnNameB.setUpperBound("B");
> which would be equivalent:
> select * from some_table where column_name="A" or column_name="B"
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