SQL，CROSS JOIN速度优化

问题其实在于下面SQL的string1_emb和string2_emb的数据传输是速度瓶颈

            SELECT  /*+ MAPJOIN(a2) */a1.string1,a2.string2,a1.string1_emb,a2.string2_embFROM    (SELECT  string1,string1_embFROM    table1) a1CROSS JOIN  (SELECT  string2,string2_embFROM    table2) a2    

改成先cross join的时候只string1和string2，再按string1/string2 join上embedding

            SELECT  /*+ MAPJOIN(a2) */a1.string1,a2.string2FROM    (SELECT  string1FROM    table1) a1CROSS JOIN  (SELECT  string2FROM    table2) a2