[CALCITE-509] RelMdColumnUniqueness uses ImmutableBitSet.Builder twice, gets NullPointerException

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Fix Version/s: 1.0.0-incubating
• Labels: newbie
• Assignee: Julian Hyde
• Reporter: Julian Hyde
• Created: 03/Dec/14 18:51
• Updated: 08/Feb/15 08:56
• Resolved: 03/Dec/14 20:50

Description

RelMdColumnUniqueness.areColumnsUnique gets the following stack:

ava.lang.NullPointerException
	at org.apache.calcite.util.ImmutableBitSet.countBits(ImmutableBitSet.java:280)
	at org.apache.calcite.util.ImmutableBitSet.access$600(ImmutableBitSet.java:36)
	at org.apache.calcite.util.ImmutableBitSet$Builder.cardinality(ImmutableBitSet.java:799)
	at org.apache.calcite.rel.metadata.RelMdColumnUniqueness.areColumnsUnique(RelMdColumnUniqueness.java:178)

The cause is that it populates an ImmutableBitSet.Builder, calls build on it, then calls cardinality. That is not allowed – once build has been called the builder cannot be re-used, even for cardinality.