code: protected void copyFrom(CompilerHints source) {
  		this.outputSize = source.outputSize;
  		this.outputCardinality = source.outputCardinality;
  		this.avgOutputRecordSize = source.avgOutputRecordSize;
  		this.filterFactor = source.filterFactor;
  		
  		if (source.uniqueFields != null && source.uniqueFields.size() > 0) {
  			if (this.uniqueFields == null) {
  				this.uniqueFields = new HashSet<FieldSet>();
  			} else {
  				this.uniqueFields.clear();
  			}
  			
  			this.uniqueFields.addAll(source.uniqueFields);
  		}
  	}
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