implemented UNION (and a few other query operators)

[markoszah]

No description provided.

[jinzha]

Swap SEQ_AGGR and SORT to maintain ascending order?

[markoszah]

Done

[jinzha]

The maxReadKB of QueryRequest must be >=0. If origRequest.maxReadKB is not specified, it defaults to 0, then origRequest.getMaxReadKB() - theRCB.getReadKB() is negative and results in an IllegalArgumentException.

     public QueryRequest setMaxReadKB(int maxReadKB) {
        if (maxReadKB < 0) {
            throw new IllegalArgumentException("maxReadKB must be >= 0");
        }
        this.maxReadKB = maxReadKB;
        return this;
    }

[markoszah]

Good point! To simplify things, I have modified the UnionIter so that when it gets done with the current branch it suspends the query instead of moving to the next branch (and thus sending another remote request).

[jinzha]

The Javadoc for the parameters proxyStatement, namespace, and tableName should be updated accordingly.

[markoszah]

Done

[jinzha]

The existing changes look good to me. Support for UNION across stores will be handled in a separate PR.