我通过SQL Server Management Studio执行的以下查询非常缓慢。
输入表tbl_sb12_bhs有大约40000条记录，一小时后只处理40条记录。
这里可以改变什么来使这个运行更快一点？
DECLARE @bsrange INT
SET @bsrange = 0
WHILE @bsrange <= (SELECT max([p_a_l_out])
FROM [DB001].[FD\f7].[tbl_sb12_bhs])
BEGIN
INSERT INTO [FD\f7].tbl_sb13_b_lin1
(aId,
p_a_l_out,
bs_id,
bs_db,
bs_tbl,
bs_column,
Int1,
cd1,
Hop1,
Int2,
cd2,
Hop2,
Int3,
cd3,
Hop3,
Int4,
cd4,
Hop4,
Int5,
cd5,
Hop5,
Int6,
cd6,
Hop6,
Int7,
cd7,
Hop7,
Int8,
cd8,
Hop8,
Int9,
cd9,
Hop9,
Int10,
cd10,
Hop10,
Int11,
cd11,
Hop11,
Int12,
cd12,
Hop12,
Int13,
cd13,
Hop13,
Int14,
cd14,
Hop14,
Int15,
cd15,
Hop15,
Int16,
cd16,
Hop16)
SELECT DISTINCT tbl_sb12_bhs.aId,
tbl_sb12_bhs.p_a_l_out,
tbl_sb12_bhs.bs_id,
tbl_sb12_bhs.bs_db,
tbl_sb12_bhs.bs_tbl,
tbl_sb12_bhs.bs_column,
tbl_rpt_val_pt_crl.pt_el_Int AS Int1,
tbl_rpt_val_pt_crl.user_cd AS cd1,
tbl_rpt_val_pt_crl.cfk_upel AS Hop1,
tbl_rpt_val_pt_crl_1.pt_el_Int AS Int2,
tbl_rpt_val_pt_crl_1.user_cd AS cd2,
tbl_rpt_val_pt_crl_1.cfk_upel AS Hop2,
tbl_rpt_val_pt_crl_2.pt_el_Int AS Int3,
tbl_rpt_val_pt_crl_2.user_cd AS cd3,
tbl_rpt_val_pt_crl_2.cfk_upel AS Hop3,
tbl_rpt_val_pt_crl_3.pt_el_Int AS Int4,
tbl_rpt_val_pt_crl_3.user_cd AS cd4,
tbl_rpt_val_pt_crl_3.cfk_upel AS Hop4,
tbl_rpt_val_pt_crl_4.pt_el_Int AS Int5,
tbl_rpt_val_pt_crl_4.user_cd AS cd5,
tbl_rpt_val_pt_crl_4.cfk_upel AS Hop5,
tbl_rpt_val_pt_crl_5.pt_el_Int AS Int6,
tbl_rpt_val_pt_crl_5.user_cd AS cd6,
tbl_rpt_val_pt_crl_5.cfk_upel AS Hop6,
tbl_rpt_val_pt_crl_6.pt_el_Int AS Int7,
tbl_rpt_val_pt_crl_6.user_cd AS cd7,
tbl_rpt_val_pt_crl_6.cfk_upel AS Hop7,
tbl_rpt_val_pt_crl_7.pt_el_Int AS Int8,
tbl_rpt_val_pt_crl_7.user_cd AS cd8,
tbl_rpt_val_pt_crl_7.cfk_upel AS Hop8,
tbl_rpt_val_pt_crl_8.pt_el_Int AS Int9,
tbl_rpt_val_pt_crl_8.user_cd AS cd9,
tbl_rpt_val_pt_crl_8.cfk_upel AS Hop9,
tbl_rpt_val_pt_crl_9.pt_el_Int AS Int10,
tbl_rpt_val_pt_crl_9.user_cd AS cd10,
tbl_rpt_val_pt_crl_9.cfk_upel AS Hop10,
tbl_rpt_val_pt_crl_10.pt_el_Int AS Int11,
tbl_rpt_val_pt_crl_10.user_cd AS cd11,
tbl_rpt_val_pt_crl_10.cfk_upel AS Hop11,
tbl_rpt_val_pt_crl_11.pt_el_Int AS Int12,
tbl_rpt_val_pt_crl_11.user_cd AS cd12,
tbl_rpt_val_pt_crl_11.cfk_upel AS Hop12,
tbl_rpt_val_pt_crl_12.pt_el_Int AS Int13,
tbl_rpt_val_pt_crl_12.user_cd AS cd13,
tbl_rpt_val_pt_crl_12.cfk_upel AS Hop13,
tbl_rpt_val_pt_crl_13.pt_el_Int AS Int14,
tbl_rpt_val_pt_crl_13.user_cd AS cd14,
tbl_rpt_val_pt_crl_13.cfk_upel AS Hop14,
tbl_rpt_val_pt_crl_14.pt_el_Int AS Int15,
tbl_rpt_val_pt_crl_14.user_cd AS cd15,
tbl_rpt_val_pt_crl_14.cfk_upel AS Hop15,
tbl_rpt_val_pt_crl_15.pt_el_Int AS Int16,
tbl_rpt_val_pt_crl_15.user_cd AS cd16,
tbl_rpt_val_pt_crl_15.cfk_upel AS Hop16
FROM (SELECT DISTINCT pk_a AS aId,
p_a_l_out,
bs_id,
bs_db,
bs_tbl,
bs_column,
hop_pt_id_1,
hop_pt_id_2,
hop_pt_id_3,
hop_pt_id_4,
hop_pt_id_5,
hop_pt_id_6,
hop_pt_id_7,
hop_pt_id_8,
hop_pt_id_9,
hop_pt_id_10,
hop_pt_id_11,
hop_pt_id_12,
hop_pt_id_13,
hop_pt_id_14,
hop_pt_id_15,
hop_pt_id_16
FROM [FD\f7].tbl_sb12_bhs
WHERE [p_a_l_out] >= @bsrange
AND [p_a_l_out] < ( @bsrange + 1 )) AS tbl_sb12_bhs
LEFT JOIN tbl_rpt_val_pt_crl
ON tbl_sb12_bhs.hop_pt_id_1 = tbl_rpt_val_pt_crl.sk_el_pt
LEFT JOIN tbl_rpt_val_pt_crl AS tbl_rpt_val_pt_crl_1
ON tbl_sb12_bhs.hop_pt_id_2 = tbl_rpt_val_pt_crl_1.sk_el_pt
LEFT JOIN tbl_rpt_val_pt_crl AS tbl_rpt_val_pt_crl_2
ON tbl_sb12_bhs.hop_pt_id_3 = tbl_rpt_val_pt_crl_2.sk_el_pt
LEFT JOIN tbl_rpt_val_pt_crl AS tbl_rpt_val_pt_crl_3
ON tbl_sb12_bhs.hop_pt_id_4 = tbl_rpt_val_pt_crl_3.sk_el_pt
LEFT JOIN tbl_rpt_val_pt_crl AS tbl_rpt_val_pt_crl_4
ON tbl_sb12_bhs.hop_pt_id_5 = tbl_rpt_val_pt_crl_4.sk_el_pt
LEFT JOIN tbl_rpt_val_pt_crl AS tbl_rpt_val_pt_crl_5
ON tbl_sb12_bhs.hop_pt_id_6 = tbl_rpt_val_pt_crl_5.sk_el_pt
LEFT JOIN tbl_rpt_val_pt_crl AS tbl_rpt_val_pt_crl_6
ON tbl_sb12_bhs.hop_pt_id_7 = tbl_rpt_val_pt_crl_6.sk_el_pt
LEFT JOIN tbl_rpt_val_pt_crl AS tbl_rpt_val_pt_crl_7
ON tbl_sb12_bhs.hop_pt_id_8 = tbl_rpt_val_pt_crl_7.sk_el_pt
LEFT JOIN tbl_rpt_val_pt_crl AS tbl_rpt_val_pt_crl_8
ON tbl_sb12_bhs.hop_pt_id_9 = tbl_rpt_val_pt_crl_8.sk_el_pt
LEFT JOIN tbl_rpt_val_pt_crl AS tbl_rpt_val_pt_crl_9
ON tbl_sb12_bhs.hop_pt_id_10 = tbl_rpt_val_pt_crl_9.sk_el_pt
LEFT JOIN tbl_rpt_val_pt_crl AS tbl_rpt_val_pt_crl_10
ON tbl_sb12_bhs.hop_pt_id_11 = tbl_rpt_val_pt_crl_10.sk_el_pt
LEFT JOIN tbl_rpt_val_pt_crl AS tbl_rpt_val_pt_crl_11
ON tbl_sb12_bhs.hop_pt_id_12 = tbl_rpt_val_pt_crl_11.sk_el_pt
LEFT JOIN tbl_rpt_val_pt_crl AS tbl_rpt_val_pt_crl_12
ON tbl_sb12_bhs.hop_pt_id_13 = tbl_rpt_val_pt_crl_12.sk_el_pt
LEFT JOIN tbl_rpt_val_pt_crl AS tbl_rpt_val_pt_crl_13
ON tbl_sb12_bhs.hop_pt_id_14 = tbl_rpt_val_pt_crl_13.sk_el_pt
LEFT JOIN tbl_rpt_val_pt_crl AS tbl_rpt_val_pt_crl_14
ON tbl_sb12_bhs.hop_pt_id_15 = tbl_rpt_val_pt_crl_14.sk_el_pt
LEFT JOIN tbl_rpt_val_pt_crl AS tbl_rpt_val_pt_crl_15
ON tbl_sb12_bhs.hop_pt_id_16 = tbl_rpt_val_pt_crl_15.sk_el_pt
SET @bsrange = @bsrange + 1
END
答案 0 :(得分：0)
如果目标上有索引或索引，那么SQL将重新索引每一行。我将禁用目标表上的任何索引，然后在插入完成时重新编译它们。 Id批量插入inro范围（比方说）5k记录，这样任何阻塞都会减少，或者我会在结果中选择select和bcp来创建临时文件。因为你每次在一次记录插入之前做了那些可怕的左连接。 SQL只能不能优化大约7或8个左或右连接。我的猜测是，表中插入的索引很少或没有索引，这意味着每个连接都会扫描一个表，或者每插入一行就扫描17个表。对不起，但这个方法在每个阶段都是错误的。或者你可以让老板给你买一个约会中心....
答案 1 :(得分：0)
我最好的猜测是，它很慢，因为你一次性完成了许多密集的操作。没有任何样本数据很难，但我可以尝试提出一些建议。
根据你的说法，它只会在一小时后处理40条记录，这就是循环内部正在减慢你的速度。
SELECT DISTINCT并不便宜，因为它必须比较所有数据，而且你也要比较很多列。如果可以的话，如果将列数限制为不同选择所需的最小值，然后将其自身连接到原始表，则可能会更快地运行。它应该足够简单，可以单独测试其余部分，以确保获得相同的结果以及是否更快。
此外，您拥有的联盟越多，性能就越差......我们为正常化付出的代价。
无论如何，我会退后一步，尝试将其分解为最小的工作单元，然后你可以单独测试每一个，直到找到罪魁祸首。这样做，你可能会想到一个更好的方法来做到这一点。同样，如果没有任何样本数据，这对我来说很难帮助。
答案 2 :(得分：0)
您可能想要做的另一件事是最初将连接加入临时表，然后引用它。您不必每次都进行不同的连接或连接。只需为bsrange添加where子句。
所以它会是这样的：
Create temporary table with as much of the joins/distinct as you can.
while.....
insert into [FD\f7].tbl_sb13_b_lin1
select * from temptable where [p_a_l_out] >= @bsrange
AND [p_a_l_out] < ( @bsrange + 1 )