Potential memory leak in the serialize method of varlen type

[chenboy]

In

peloton/src/type/varlen_type.cpp

Line 181 in 3451aef

data = (pool == nullptr) ? new char[size] : (char *)pool->Allocate(size);

, we'll create a new char array to buffer the serialized varlen type if no memory pool is specified, I think it will not be deleted afterwards so this may cause a memory leak. I found this when working on the explain executor, which returns the plan string as a tuple.

Detail see this build:

jenkins.db.cs.cmu.edu:8080/blue/organizations/jenkins/peloton/detail/PR-1357/4/