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https://issues.apache.org/jira/browse/PHOENIX-4288?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16269168#comment-16269168
]
ASF GitHub Bot commented on PHOENIX-4288:
-----------------------------------------
Github user JamesRTaylor commented on a diff in the pull request:
https://github.com/apache/phoenix/pull/281#discussion_r153574645
--- Diff:
phoenix-core/src/main/java/org/apache/phoenix/optimize/QueryOptimizer.java ---
@@ -91,8 +91,23 @@ public QueryPlan optimize(PhoenixStatement statement,
SelectStatement select, Co
}
public QueryPlan optimize(QueryPlan dataPlan, PhoenixStatement
statement, List<? extends PDatum> targetColumns, ParallelIteratorFactory
parallelIteratorFactory) throws SQLException {
- List<QueryPlan>plans = getApplicablePlans(dataPlan, statement,
targetColumns, parallelIteratorFactory, true);
- return plans.get(0);
+ List<QueryPlan> plans = getApplicablePlans(dataPlan, statement,
targetColumns, parallelIteratorFactory, false);
+ if (plans.size() == 1) {
+ return plans.get(0);
+ }
+
+ // Get the best plan based on their costs. Costs will be ZERO if
stats are not
+ // available, thus the first plan will be returned.
+ Cost minCost = null;
+ QueryPlan bestPlan = null;
+ for (QueryPlan plan : plans) {
+ Cost cost = plan.getCost();
+ if (minCost == null || cost.compareTo(minCost) < 0) {
+ minCost = cost;
+ bestPlan = plan;
+ }
+ }
+ return bestPlan;
--- End diff --
I'm still not seeing this change. The only existing method that should
change in QueryOptimizer is this private one:
private List<QueryPlan> getApplicablePlans(QueryPlan dataPlan,
PhoenixStatement statement, List<? extends PDatum> targetColumns,
ParallelIteratorFactory parallelIteratorFactory, boolean stopAtBestPlan) throws
SQLException {
The only change necessary should be to call a new method that orders the
plans according to cost.
> Indexes not used when ordering by primary key
> ---------------------------------------------
>
> Key: PHOENIX-4288
> URL: https://issues.apache.org/jira/browse/PHOENIX-4288
> Project: Phoenix
> Issue Type: Sub-task
> Reporter: Marcin Januszkiewicz
> Assignee: Maryann Xue
> Labels: CostBasedOptimization
>
> We have a table
> CREATE TABLE t (
> rowkey VARCHAR PRIMARY KEY,
> c1 VARCHAR,
> c2 VARCHAR
> )
> which we want to query by doing partial matches on c1, and keep the ordering
> of the source table:
> SELECT rowkey, c1, c2 FROM t where c1 LIKE 'X0%' ORDER BY rowkey;
> We expect most queries to select a small subset of the table, so we create an
> index to speed up searches:
> CREATE LOCAL INDEX t_c1_ix ON t (c1);
> However, this index will not be used since Phoenix will always choose not to
> resort the data.
> In our actual use case, adding index hints is not a practical solution.
> See also discussion at:
> https://lists.apache.org/thread.html/26ab58288eb811d2f074c3f89067163d341e5531fb581f3b2486cf43@%3Cuser.phoenix.apache.org%3E
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