[HIVE-10621] serde typeinfo equals methods are not symmetric

• Type: Bug
• Status: Resolved
• Priority: Minor
• Resolution: Pending Closed
• Fix Version/s: 1.3.0
• Component/s: Serializers/Deserializers
• Assignee: Alexander Pivovarov
• Reporter: Alexander Pivovarov
• Created: 06/May/15 04:45
• Updated: 12/May/15 21:32
• Resolved: 12/May/15 21:32

Description

correct equals method implementation should start with

  if (this == other) {
    return true;
  }
  if (other == null || getClass() != other.getClass()) {
    return false;
  }

DecimalTypeInfo, PrimitiveTypeInfo, VarcharTypeInfo, CharTypeInfo, HiveDecimalWritable equals method implementation starts with

  if (other == null || !(other instanceof <class_name>)) {
    return false
  }

• first of all check for null is redundant
• the second issue is that "other instanceof <class_name>" check is not symmetric.

contract of equals() implies that, a.equals(b) is true if and only if b.equals(a) is true
Current implementation violates this contract.
e.g.
DecimalTypeInfo instanceof PrimitiveTypeInfo is true
but
PrimitiveTypeInfo instanceof DecimalTypeInfo is false

See more details here http://stackoverflow.com/questions/6518534/equals-method-overrides-equals-in-superclass-and-may-not-be-symmetric

Issue Links

• links to: http://stackoverflow.com/questions/6518534/equals-method-overrides-equals-in-superclass-and-may-not-be-symmetric
• links to: https://reviews.apache.org/r/33880/