explain
select T0.* , T1.HIDE
from TABLE1 as T0
left JOIN
( select key1, key2, count(*) AS HIDE  
	from TABLE1
	GROUP BY key1, key2
) as T1
ON T0.key1 = T1.key1 AND T0.key2 = T1.key2;

-- Ignite v2.13.0 and v2.14.0 
-- execution time  8 seconds with 2100 records
-- execution time 22 seconds with 4400 records

SELECT
    T0.INTERNALID,
    T0.COLUMN1,
    T0.COLUMN2,
    T0.COLUMN3,
    T0.COLUMN4,
    T0.COLUMN5,
    T0.COLUMN6,
    T0.COLUMN7,
    T0.COLUMN8,
    T0.COLUMN9,
    T0.COLUMN10,
    T0.KEY1,
    T0.KEY2,
    T1.HIDE
FROM PUBLIC.TABLE1 T0
    /* PUBLIC.TABLE1.__SCAN_ */
LEFT OUTER JOIN (
    SELECT
        KEY1,
        KEY2,
        COUNT(*) AS HIDE
    FROM PUBLIC.TABLE1
    GROUP BY KEY1, KEY2
) T1
    /* SELECT
        KEY1,
        KEY2,
        COUNT(*) AS HIDE
    FROM PUBLIC.TABLE1
        /++ PUBLIC.TABLE1.__SCAN_ ++/
    WHERE (KEY1 IS ?1)
        AND (KEY2 IS ?2)
    GROUP BY KEY1, KEY2: KEY1 = T0.KEY1
        AND KEY2 = T0.KEY2
     */
    ON (T0.KEY1 = T1.KEY1)
    AND (T0.KEY2 = T1.KEY2)
	
	
-- Ignite v 2.7.6 
-- execution time  3ms with 2100 records
-- execution time  4ms seconds with 4400 records
	
SELECT
    T0__Z0__INTERNALID AS INTERNALID,
    T0__Z0__COLUMN1 AS COLUMN1,
    T0__Z0__COLUMN2 AS COLUMN2,
    T0__Z0__COLUMN3 AS COLUMN3,
    T0__Z0__COLUMN4 AS COLUMN4,
    T0__Z0__COLUMN5 AS COLUMN5,
    T0__Z0__COLUMN6 AS COLUMN6,
    T0__Z0__COLUMN7 AS COLUMN7,
    T0__Z0__COLUMN8 AS COLUMN8,
    T0__Z0__COLUMN9 AS COLUMN9,
    T0__Z0__COLUMN10 AS COLUMN10,
    T0__Z0__KEY1 AS KEY1,
    T0__Z0__KEY2 AS KEY2,
    T1__Z2.HIDE AS HIDE
FROM (
    SELECT
        __C0_0 AS T0__Z0__COLUMN10,
        __C0_1 AS T0__Z0__COLUMN1,
        __C0_2 AS T0__Z0__COLUMN2,
        __C0_3 AS T0__Z0__COLUMN3,
        __C0_4 AS T0__Z0__COLUMN4,
        __C0_5 AS T0__Z0__KEY2,
        __C0_6 AS T0__Z0__COLUMN5,
        __C0_7 AS T0__Z0__KEY1,
        __C0_8 AS T0__Z0__COLUMN6,
        __C0_9 AS T0__Z0__INTERNALID,
        __C0_10 AS T0__Z0__COLUMN7,
        __C0_11 AS T0__Z0__COLUMN8,
        __C0_12 AS T0__Z0__COLUMN9
    FROM PUBLIC.__T0
    ORDER BY 8, 6
) __Z3
    /* SELECT
        __C0_0 AS T0__Z0__COLUMN10,
        __C0_1 AS T0__Z0__COLUMN1,
        __C0_2 AS T0__Z0__COLUMN2,
        __C0_3 AS T0__Z0__COLUMN3,
        __C0_4 AS T0__Z0__COLUMN4,
        __C0_5 AS T0__Z0__KEY2,
        __C0_6 AS T0__Z0__COLUMN5,
        __C0_7 AS T0__Z0__KEY1,
        __C0_8 AS T0__Z0__COLUMN6,
        __C0_9 AS T0__Z0__INTERNALID,
        __C0_10 AS T0__Z0__COLUMN7,
        __C0_11 AS T0__Z0__COLUMN8,
        __C0_12 AS T0__Z0__COLUMN9
    FROM PUBLIC.__T0
        /++ PUBLIC."merge_sorted" ++/
    ORDER BY 8, 6
    /++ index sorted ++/
     */
LEFT OUTER JOIN (
    SELECT
        __C1_0 AS KEY1,
        __C1_1 AS KEY2,
        CAST(SUM(__C1_2) AS BIGINT) AS HIDE
    FROM PUBLIC.__T1
    GROUP BY __C1_0, __C1_1
    ORDER BY 1, 2
) T1__Z2
    /* SELECT
        __C1_0 AS KEY1,
        __C1_1 AS KEY2,
        CAST(SUM(__C1_2) AS BIGINT) AS HIDE
    FROM PUBLIC.__T1
        /++ PUBLIC."merge_scan": __C1_0 IS ?1
            AND __C1_1 IS ?2
         ++/
    WHERE (__C1_0 IS ?1)
        AND (__C1_1 IS ?2)
    GROUP BY __C1_0, __C1_1
    ORDER BY 1, 2: KEY1 = T0__Z0__KEY1
        AND KEY2 = T0__Z0__KEY2
     */
    ON (T0__Z0__KEY1 = T1__Z2.KEY1)
    AND (T0__Z0__KEY2 = T1__Z2.KEY2)