presto-main/src/main/java/io/prestosql/operator/HashBuilderOperator.java/HashBuilderOperator/updateIndex
class HashBuilderOperator:    private void updateIndex(Page page)
    {
        index.addPage(page);

        if (spillEnabled) {
            localRevocableMemoryContext.setBytes(index.getEstimatedSize().toBytes());
        }
        else {
            if (!localUserMemoryContext.trySetBytes(index.getEstimatedSize().toBytes())) {
                index.compact();
                localUserMemoryContext.setBytes(index.getEstimatedSize().toBytes());
            }
        }
        operatorContext.recordOutput(page.getSizeInBytes(), page.getPositionCount());
    }