场景是BE FE有混搭的节点，发现有查询被mem_limit阻止。根据query_id在审计日志里面查询到是root用户在__internal_schema的sql peak_memory_bytes很高。sql查询执行结构似乎是为了获取一个最小值和最大值，目标表数据量比较大 TB级别，想问下这种系统sql是什么作用？哪里有可以限制的参数？
1 Answers
SELECT CONCAT('18391', '-', '-1', '-', 'timestamp') AS id, 0 AS catalog_id, 10431 AS db_id, 18391 AS tbl_id, -1 AS idx_id, 'timestamp' AS col_id, NULL AS part_id, 22404824371 AS row_count, SUM(t1.count) * COUNT(1) / (SUM(t1.count) - SUM(IF(t1.count = 1, 1, 0)) + SUM(IF(t1.count = 1, 1, 0)) * SUM(t1.count) / 22404824371) as ndv, IFNULL(SUM(IF(t1.column_key IS NULL, t1.count, 0)), 0) * 26.134001132030455 as null_count, SUBSTRING(CAST('2025-02-08 17:00:00.000' AS STRING), 1, 1024) AS min, SUBSTRING(CAST('2025-02-19 11:26:24.910' AS STRING), 1, 1024) AS max, SUM(t1.count) * 8 * 26.134001132030455 AS data_size, NOW() FROM ( SELECT t0.timestamp as column_key, COUNT(1) as count FROM (SELECT timestamp FROM internal.xxxdb.xxxtable TABLET(1665499, 1715004, 1762814, 1808276, 1869398, 1886601, 1888781, 1938311, 1992905, 2033692, 2080454, 2142049, 2209657, 2277632, 2345012, 2414445, 2473452, 2512523, 2535477, 2563859, 2591162, 2612394, 2642246, 2664421, 2687637, 2709782, 2732933, 2755996, 2791393, 2836631, 2889050, 2944963, 2977615, 3017543, 3066270, 3124825, 3186280, 3255029, 3323463, 3393955, 3450862, 3484915, 3509904, 3551078, 3584361, 3610861, 3638162, 3671081, 3718145, 3765053, 3812211, 3854007, 3901030, 3957975, 4021458, 4071861, 4105497, 4155455, 4221618, 4296130, 4379676, 4466635, 4554881, 4642909, 4718968, 4770848, 4815871, 4877605, 4933067, 4979520, 5029479, 5078792, 5129404, 5181545, 5232878, 5278938, 5324772, 5384005, 5448508, 5514658, 5565896, 5625998, 5694631, 5771872, 5856608, 5942218, 6031493, 6119996, 6199086, 6255265, 6302479, 6371550, 6428999, 6474208, 6522206, 6567541, 6621835, 6673661, 6722863, 6768639, 6818073, 6879330, 6946175, 7011898, 7065913, 7123132, 7191762, 7271527, 7358076, 7447534, 7535781, 7623596, 7704129, 7761213, 7807877, 7867134, 7922737, 7968291, 8015870, 8062808, 8112680, 8161793, 8209655, 8253838, 8307337, 8368817, 8432558, 8495891, 8547977, 8603893, 8671331, 8751480, 8835712, 8922446, 9009055, 9096429, 9176093, 9229873, 9279119, 9340638, 9395295, 9440542, 9487109, 9533766, 9581931, 9629595, 9678523, 9723732, 9778585, 9840096, 9904369, 9968367, 10020503, 10075544, 10140951, 10213275, 10294864, 10375558, 10458141, 10540197, 10614725, 10666795, 10713720, 10769408, 10819275, 10863968, 10911244, 10956922, 11003093, 11048720, 11094694, 11139355, 11194697, 11256752, 11322270, 11386050, 11440988, 11498398, 11563110, 11639153, 11719023, 11797862, 11880656, 11960276, 12033436, 12086083, 12132547, 12186428, 12234384, 12278785, 12325638, 12368521, 12412837, 12456685, 12500469, 12543351, 12598394, 12660075, 12723928, 12786124, 12839407, 12893926, 12958598, 13033108, 13112720, 13191849, 13269135, 13346274, 13417892, 13468493, 13517624, 13576942, 13634893, 13687063, 13734498, 13782702, 13831879, 13881064, 13919600, 13972765, 14022642, 14082146, 14144749, 14205209, 14256138, 14311246, 14375425, 14445849, 14523625, 14600794, 14675794, 14750855, 14820001, 14867938, 14917840, 14979232, 15040612, 15090997, 15137232, 15185251, 15234080, 15283314, 15331629, 15376079, 15425503, 15483621, 15545771, 15605686, 15659351, 15715180, 15780613, 15853601, 15932662, 16008231, 16087319, 16164534, 16233581, 16283496, 16332309) ) as t0 GROUP BY t0.timestamp ) as t1