Hello,   Observing "union all" is dropping records with all null/empty fields.    CREATE tABLE IF NOT EXISTS as_adventure.t1 ( productsubcategorykey INT, productline STRING); insert into t1 values (1,'l1'); insert into t1 values (2,'l1'); insert into t1 values (1,'l2'); insert into t1 values (3,'l3'); insert into t1 values (null,''); select * from t1; SELECT MIN(t_53.c_41) c_41, CAST(NULL AS DOUBLE) c_43, CAST(NULL AS BIGINT) c_44, t_53.c2 c2, t_53.c3s0 c3s0, t_53.c4 c4, t_53.c5s0 c5s0 FROM ( SELECT t.productsubcategorykey c_41, t.productline c2, t.productline c3s0, t.productsubcategorykey c4, t.productsubcategorykey c5s0 FROM as_adventure.t1 t WHERE true GROUP BY 2, 3, 4, 5 ) t_53 GROUP BY 4, 5, 6, 7 UNION ALL SELECT MIN(t_53.c_41) c_41, CAST(NULL AS DOUBLE) c_43, CAST(NULL AS BIGINT) c_44, t_53.c2 c2, t_53.c3s0 c3s0, t_53.c4 c4, t_53.c5s0 c5s0 FROM ( SELECT t.productsubcategorykey c_41, t.productline c2, t.productline c3s0, t.productsubcategorykey c4, t.productsubcategorykey c5s0 FROM as_adventure.t1 t WHERE true GROUP BY 2, 3, 4, 5 ) t_53 GROUP BY 4, 5, 6, 7      Above query only shows 8 records instead of 10 records.    This is observed for the following versions: 5.7.6 5.8.5 5.9.3 5.10.2 5.11.2 5.12.2 5.13.1 5.14.0 5.14.4 5.15.1 5.16.2 6.0.1 6.1.1 6.2.0 6.3.1 ... View more