Sergey Soldatov created PHOENIX-3152:
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Summary: Incorrect comparator in QueryOptimizer may cause
IllegalArgumentException
Key: PHOENIX-3152
URL: https://issues.apache.org/jira/browse/PHOENIX-3152
Project: Phoenix
Issue Type: Bug
Affects Versions: 4.8.0
Reporter: Sergey Soldatov
The problem code is in QueryOptimizer#orderPlansBestToWorst
When we have a lot of local similar indexes, all of them comes to the array of
best candidates. After that we try to sort them using our own Comparator. In
the compare we check first:
1. bound pk columns count
2. groupBy order
3. number of columns
for two local indexes on different columns first 3 steps always passed (since
they are equal)
And now we execute the following checks:
{noformat}
// If all things are equal, don't choose local index as it
forces scan
// on every region (unless there's no start/stop key)
if (table1.getIndexType() == IndexType.LOCAL) {
return
plan1.getContext().getScanRanges().getRanges().isEmpty() ? -1 : 1;
}
if (table2.getIndexType() == IndexType.LOCAL) {
return
plan2.getContext().getScanRanges().getRanges().isEmpty() ? 1 : -1;
}
{noformat}
obvious that for similar two plans with similar scan ranges {{compare (plan1,
plan2)}} and {{compare(plan2, plan1)}} will return the same result (1 if ranges
are not empty, -1 otherwise). This may cause following exception from
{{Collections.sort}} :
{noformat}
at java.util.TimSort.mergeLo(TimSort.java:777)
at java.util.TimSort.mergeAt(TimSort.java:514)Listening for transport
at java.util.TimSort.mergeCollapse(TimSort.java:441)
at java.util.TimSort.sort(TimSort.java:245)
at java.util.Arrays.sort(Arrays.java:1512)
at java.util.ArrayList.sort(ArrayList.java:1454)
at java.util.Collections.sort(Collections.java:175)
{noformat}
I would suggest to add a check that if both plans are local indexes, then
consider them equal, otherwise execute the check. [~jamestaylor], [~ram_krish]
any thoughts?
[[email protected]] FYI
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