public boolean isPrefetch() {
        if (prefetch!=null) return prefetch;

        if (tensorType.isPresent()) {
            return false;
        }
        if (CollectionType.SINGLE.equals(collectionType)) {
            return true;
        }

        return false;
    }
<p>Returns whether this attribute should be included in the "attributeprefetch" summary
which is returned to the Qrs by prefetchAttributes, used by blending, uniquing etc.

<p>Single value attributes are prefetched by default if summary is true.
Multi value attributes are not.</p>
config-model/src/main/java/com/yahoo/schema/document/Attribute.java