达梦分布式集群DPC_优化案例01_yxy

1 需优化sql

分布式架构为3BP，1SP，1MP
FLD表： 27亿行
S表： 1亿行

SELECT COUNT(1) FROM  (
SELECT *... FROM  FLD  INNER JOIN  S
ON FLD.ID = S.ID AND FLD.PNO=S.PNO AND FLD.SID= S.SID
WHERE FLD.GCODE NOT IN ('2','4') AND FLD.VFLAG = '1' AND S.VFLAG='1'   AND S.RSFLAG = '0' AND S.GCODE NOT IN ('2','4') AND S.STIME >= '2024-01-01' AND S.STIME < '2024-02-01' --AND FLD.FTIME >'2023-11-01'  （后面加上的条件）GROUP BY ......) A

2 优化思路

①利用分布式的分区裁剪优化
分区裁剪优化 原理

一级分区方式都用范围分区
两个时间条件做分区列（FTIME 和 STIME），能利用分区裁剪，能减少不必要的扫描

②利用PWJ，分区智能连接优化
分区智能连接+改变分发方式 原理

二级分区方式都用HASH分区
分区列都为PNO，能够利用PWJ优化，每个节点4个子表，一共12个子表

③改变表的分发方式，提高并发来提升性能

 /*+ PARALLEL(16) dpc(1 L_NO_R_NO)*/ /*+ PARALLEL(32) dpc(1 l_bro)*/

④覆盖索引

CREATE INDEX YXY2025 on FLD(...,FTIME,...) UNUSABLE;
ALTER INDEX YXY2025 rebuild SHARE ASYNCHRONOUS 32;CREATE INDEX YXY2025SFULL on S(STIME,...) UNUSABLE;
ALTER INDEX YXY2025SFULL rebuild SHARE ASYNCHRONOUS 64;

3 执行计划分析

①调整表结构（二级分区）、加覆盖索引、并发32、并走PWJ优化，执行耗时324s

加hint  /*+ dpc(1 L_NO_R_NO)*/ 
1   #NSET2: [7019, 1, 794] 
2     #PRJT2: [7019, 1, 794]; exp_num(1), is_atom(FALSE) 
3       #AAGR2: [7019, 1, 794]; grp_num(0), sfun_num(1), distinct_flag[0]; slave_empty(0)
4         #ERECV: [7019, 1, 794]; stask_no(-1), l_stask_no(1), n_key(0), in_turn(0), trig(0)
5           #ESEND: [7019, 1, 794]; stask_no(1), type(DIRECT), sites(4:32), sql_invoke(0), pwj_opt(0), table(-); INFO_BITS(0x8)
6             #AAGR2: [7019, 1, 794]; grp_num(0), sfun_num(1), distinct_flag[0]; slave_empty(0)
7               #PRJT2: [7019, 5444027, 794]; exp_num(0), is_atom(FALSE) 
8                 #HAGR2: [7019, 5444027, 794]; grp_num(7), sfun_num(0); slave_empty(0) keys(DMTEMPVIEW_889276025.TMPCOL0, DMTEMPVIEW_889276025.TMPCOL1, DMTEMPVIEW_889276025.TMPCOL2, DMTEMPVIEW_889276025.TMPCOL3, DMTEMPVIEW_889276025.TMPCOL4, DMTEMPVIEW_889276025.TMPCOL5, DMTEMPVIEW_889276025.TMPCOL6) 
9                   #ERECV: [5638, 5444027, 794]; stask_no(1), l_stask_no(0), n_key(0), in_turn(0), trig(0)
10                    #ESEND: [5638, 5444027, 794]; stask_no(0), type(N_DEST), sites(2:4,3:4,1:4), sql_invoke(0), pwj_opt(0), table(-) ,keys(DMTEMPVIEW_889276025.TMPCOL0) ; INFO_BITS(0xc)
11                      #GI: [5638, 5444027, 794]; policy(LVL2_UNIT), gi_unit[0..1], scan_type[0](GE_L,FULL)
12                        #PRJT2: [5638, 5444027, 794]; exp_num(7), is_atom(FALSE) 
13                          #HASH2 INNER JOIN: [5638, 5444027, 794];  KEY_NUM(3); KEY(S.ID=FLD.ID AND S.PNO=FLD.PNO AND S.SID=FLD.SID) KEY_NULL_EQU(0, 0, 0)
14                            #GI: [605, 1328, 541]; policy(LVL2_UNIT), gi_unit[0..0], scan_type[0](FULL)
15                              #SLCT2: [605, 1328, 541]; (S.VFLAG = '1' AND S.RSFLAG = '0' AND NOT(S.GCODE IN LIST))
16                                #SSEK2: [605, 2231793, 541]; scan_type(ASC), YXY2025SFULL(S as S), scan_range[(exp_cast('2024-01-01'),min,min,min,min,min,min,min,min,min,min,min),(exp_cast('2024-02-01'),min,max,max,max,max,max,max,max,max,max,max)), is_global(0)
17                            #GI: [3464, 16497054, 253]; policy(LVL2_UNIT), gi_unit[1..1], scan_type[0](FULL)
18                              #SLCT2: [3464, 16497054, 253]; NOT(FLD.GCODE IN LIST)
19                                #SSEK2: [3464, 17365320, 253]; scan_type(ASC), YXY2025(FLD as FLD), scan_range[('1',exp_cast('2023-11-01'),max,min,min,min,min,min),('1',max,max,max,max,max,max,max)), is_global(0)--分析
①计划走了PWJ优化，连接的两表没有任何分发操作符
②sites(2:4,3:4,1:4)，指定并发没生效，因为PWJ的线程跟子表数绑定，每个节点子表数只有4个，所以并发为4
③14 #GI:...policy(LVL2_UNIT)... scan_type[0](GE_L,FULL)，总控GI，避免扫描其他不相关范围分区数据

②走广播，并发调整为16，耗时160s

加hint /*+ PARALLEL(16) dpc(1 l_bro)*/
1   #NSET2: [7019, 1, 794] 
2     #PRJT2: [7019, 1, 794]; exp_num(1), is_atom(FALSE) 
3       #AAGR2: [7019, 1, 794]; grp_num(0), sfun_num(1), distinct_flag[0]; slave_empty(0)
4         #ERECV: [7019, 1, 794]; stask_no(-1), l_stask_no(2), n_key(0), in_turn(0), trig(0)
5           #ESEND: [7019, 1, 794]; stask_no(2), type(DIRECT), sites(4:16), sql_invoke(0), pwj_opt(0), table(-); INFO_BITS(0x8)
6             #AAGR2: [7019, 1, 794]; grp_num(0), sfun_num(1), distinct_flag[0]; slave_empty(0)
7               #PRJT2: [7019, 5444027, 794]; exp_num(0), is_atom(FALSE) 
8                 #HAGR2: [7019, 5444027, 794]; grp_num(7), sfun_num(0); slave_empty(0) keys(DMTEMPVIEW_889273671.TMPCOL0, DMTEMPVIEW_889273671.TMPCOL1, DMTEMPVIEW_889273671.TMPCOL2, DMTEMPVIEW_889273671.TMPCOL3, DMTEMPVIEW_889273671.TMPCOL4, DMTEMPVIEW_889273671.TMPCOL5, DMTEMPVIEW_889273671.TMPCOL6) 
9                   #ERECV: [5638, 5444027, 794]; stask_no(2), l_stask_no(1), n_key(0), in_turn(0), trig(0)
10                    #ESEND: [5638, 5444027, 794]; stask_no(1), type(N_DEST), sites(2:16,3:16,1:16), sql_invoke(0), pwj_opt(0), table(-) ,keys(DMTEMPVIEW_889273671.TMPCOL0) ; INFO_BITS(0x8)
11                      #PRJT2: [5638, 5444027, 794]; exp_num(7), is_atom(FALSE) 
12                        #HASH2 INNER JOIN: [5638, 5444027, 794];  KEY_NUM(3); KEY(S.ID=FLD.ID AND S.PNO=FLD.PNO AND S.SID=FLD.SID) KEY_NULL_EQU(0, 0, 0); INFO_BITS(0x1)
13                          #ERECV: [605, 1328, 541]; stask_no(1), l_stask_no(0), n_key(0), in_turn(0), trig(0)
14                            #ESEND: [605, 1328, 541]; stask_no(0), type(BROADCAST), sites(2:4,3:4,1:4), sql_invoke(0), pwj_opt(0), table(-); INFO_BITS(0xd)
15                              #GI: [605, 1328, 541]; policy(PART_UNIT), gi_unit[0..0], scan_type[0](GE_L,FULL)
16                                #SLCT2: [605, 1328, 541]; (S.VFLAG = '1' AND S.RSFLAG = '0' AND NOT(S.GCODE IN LIST))
17                                  #SSEK2: [605, 2231793, 541]; scan_type(ASC), YXY2025SFULL(S as S), scan_range[(exp_cast('2024-01-01'),min,min,min,min,min,min,min,min,min,min,min),(exp_cast('2024-02-01'),min,max,max,max,max,max,max,max,max,max,max)), is_global(0)
18                          #GI: [3464, 16497054, 253]; policy(PART_UNIT), gi_unit[0..0], scan_type[0](G,FULL)
19                            #SLCT2: [3464, 16497054, 253]; NOT(FLD.GCODE IN LIST)
20                              #SSEK2: [3464, 17365320, 253]; scan_type(ASC), YXY2025(FLD as FLD), scan_range[('1',exp_cast('2023-11-01'),max,min,min,min,min,min),('1',max,max,max,max,max,max,max)), is_global(0)--分析
①计划走了广播，连接的左边为14#ESEND:...type(BROADCAST)
②并行度调整为了16[10#ESEND:...sites(2:16,3:16,1:16)]
耗时降低到160s

③走广播，并发调整为32，耗时110s

加hint /*+ PARALLEL(32) dpc(1 l_bro)*/
1   #NSET2: [7019, 1, 794] 
2     #PRJT2: [7019, 1, 794]; exp_num(1), is_atom(FALSE) 
3       #AAGR2: [7019, 1, 794]; grp_num(0), sfun_num(1), distinct_flag[0]; slave_empty(0)
4         #ERECV: [7019, 1, 794]; stask_no(-1), l_stask_no(2), n_key(0), in_turn(0), trig(0)
5           #ESEND: [7019, 1, 794]; stask_no(2), type(DIRECT), sites(4:32), sql_invoke(0), pwj_opt(0), table(-); INFO_BITS(0x8)
6             #AAGR2: [7019, 1, 794]; grp_num(0), sfun_num(1), distinct_flag[0]; slave_empty(0)
7               #PRJT2: [7019, 5444027, 794]; exp_num(0), is_atom(FALSE) 
8                 #HAGR2: [7019, 5444027, 794]; grp_num(7), sfun_num(0); slave_empty(0) keys(DMTEMPVIEW_889274813.TMPCOL0, DMTEMPVIEW_889274813.TMPCOL1, DMTEMPVIEW_889274813.TMPCOL2, DMTEMPVIEW_889274813.TMPCOL3, DMTEMPVIEW_889274813.TMPCOL4, DMTEMPVIEW_889274813.TMPCOL5, DMTEMPVIEW_889274813.TMPCOL6) 
9                   #ERECV: [5638, 5444027, 794]; stask_no(2), l_stask_no(1), n_key(0), in_turn(0), trig(0)
10                    #ESEND: [5638, 5444027, 794]; stask_no(1), type(N_DEST), sites(2:32,3:32,1:32), sql_invoke(0), pwj_opt(0), table(-) ,keys(DMTEMPVIEW_889274813.TMPCOL0) ; INFO_BITS(0x8)
11                      #PRJT2: [5638, 5444027, 794]; exp_num(7), is_atom(FALSE) 
12                        #HASH2 INNER JOIN: [5638, 5444027, 794];  KEY_NUM(3); KEY(S.ID=FLD.ID AND S.PNO=FLD.PNO AND S.SID=FLD.SID) KEY_NULL_EQU(0, 0, 0); INFO_BITS(0x1)
13                          #ERECV: [605, 1328, 541]; stask_no(1), l_stask_no(0), n_key(0), in_turn(0), trig(0)
14                            #ESEND: [605, 1328, 541]; stask_no(0), type(BROADCAST), sites(2:4,3:4,1:4), sql_invoke(0), pwj_opt(0), table(-); INFO_BITS(0xd)
15                              #GI: [605, 1328, 541]; policy(PART_UNIT), gi_unit[0..0], scan_type[0](GE_L,FULL)
16                                #SLCT2: [605, 1328, 541]; (S.VFLAG = '1' AND S.RSFLAG = '0' AND NOT(S.GCODE IN LIST))
17                                  #SSEK2: [605, 2231793, 541]; scan_type(ASC), YXY2025SFULL(S as S), scan_range[(exp_cast('2024-01-01'),min,min,min,min,min,min,min,min,min,min,min),(exp_cast('2024-02-01'),min,max,max,max,max,max,max,max,max,max,max)), is_global(0)
18                          #GI: [3464, 16497054, 253]; policy(PART_UNIT), gi_unit[0..0], scan_type[0](G,FULL)
19                            #SLCT2: [3464, 16497054, 253]; NOT(FLD.GCODE IN LIST)
20                              #SSEK2: [3464, 17365320, 253]; scan_type(ASC), YXY2025(FLD as FLD), scan_range[('1',exp_cast('2023-11-01'),max,min,min,min,min,min),('1',max,max,max,max,max,max,max)), is_global(0)--分析
①计划走了广播，连接的左边为14#ESEND:...type(BROADCAST)
②并行度调整为了32[10#ESEND:...sites(2:32,3:32,1:32)]
耗时降低到110s

4 总结

①表结构是分布式sql优化的重中之重，能决定sql是否能走分区裁剪和分区智能连接优化
②走广播的执行计划，不一定比分区智能连接性能慢，主要是合理利用服务器资源，并发增加后性能增加
③sql再加并发，线程之间协调等开销加大，效果反而会变差，性能降低
④可以增加各个节点上的子表数来增加PWJ的连接并发数，但是子表数增加后可能线程资源成为瓶颈，需要进行业务的整体考虑

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