我有一个大的oracle（Oracle Database 12c企业版第12.1.0.2.0版）表table_name，每隔15秒更新一次。 它有很多列，但我关心的是：
branch_name我要做的是：
1）获取UTC_TIMESTAMP＆lt; = current_date和UTC_TIMESTAMP＆gt;的所有记录。 current_date - 5分钟（大约125K-150K）
2）此数据将具有重复的ID_1。所以我想只记录每个ID_1在其重复项中有最大值（UTC_TIMESTAMP）的记录。所以现在我们将拥有不同的ID_1。
我尝试了什么：使用以下SQL
Name Null? Type
--------------- -------- ---------------------------------
ID_1 NOT NULL NUMBER(38)
UTC_TIMESTAMP NOT NULL TIMESTAMP(6) WITH TIME ZONE
ID_2 VARCHAR2(8)
SERVER_NAME VARCHAR2(256)
ID_3 NUMBER(38)
COUNT_1 NUMBER(38)
COUNT_2 NUMBER(38)
问题：我只能获得ID_2，ID_1和UTC_TIMESTAMP，但我也想要所有其他列。 可以使用SQL吗？
在5分钟的窗口中有大约2200个不同的ID_1和大约125K-150K的记录。 这样做是通过复制Excel工作表中的125K-150K记录并对2200 ID_1中的每一个进行过滤来查找每个ID_1的最大UTC_TIMESTAMP，这是不切实际的。 但是，如果有任何使用宏的快速方法，我也可以这样做。
示例虚拟数据：
with temp_1 as (
select m.ID_2, m.ID_1, max(utc_timestamp) max_utc_timestamp
from commsdesk.table_name m
where m.ID_2 = 'TWC'
group by m.ID_2, m.ID_1)
select f.utc_timestamp
from commsdesk.table_name f
join temp_1 t
on t.max_utc_timestamp = f.utc_timestamp
and t.ID_2 = f.ID_2
and t.ID_1 = f.ID_1;
预期产出：
ID_2 SERVER_NAME ID_3 ID_1 UTC_TIMESTAMP COUNT_1 COUNT_2
ABC PQRS.ABC.TPO 2 303 24-JUL-17 03.41.55.000000000 PM +00:00 4 0
ABC PQRS.ABC.TPO 2 1461 24-JUL-17 03.42.48.000000000 PM +00:00 1 7
ABC PQRS.ABC.TPO 2 1 24-JUL-17 03.41.36.000000000 PM +00:00 2 3
ABC PQRS.ABC.TPO 2 1461 24-JUL-17 03.41.16.000000000 PM +00:00 0 8
ABC PQRS.ABC.TPO 1 1 24-JUL-17 03.41.11.000000000 PM +00:00 5 0
ABC SRP.ROP.MTP 1 1 24-JUL-17 03.41.23.000000000 PM +00:00 0 0
ABC SRP.ROP.MTP 2 303 24-JUL-17 03.41.34.000000000 PM +00:00 0 0
ABC SRP.ROP.MTP 2 1461 24-JUL-17 03.41.31.000000000 PM +00:00 0 0
ABC SRP.ROP.MTP 4 303 24-JUL-17 03.41.26.000000000 PM +00:00 4 8
ABC SRP.ROP.MTP 2 303 24-JUL-17 03.41.20.000000000 PM +00:00 0 0
ABC SRP.ROP.MTP 1 1461 24-JUL-17 03.41.01.000000000 PM +00:00 3 8
ABC SRP.ROP.MTP 4 1 24-JUL-17 03.41.18.000000000 PM +00:00 9 1
答案 0 :(得分：2)
您可以使用max()汇总功能的the keep (dense_rank last ...)版本（或者，如果您愿意，可以使用first和min），例如：
select id_1,
max(utc_timestamp),
max(id_2) keep (dense_rank last order by utc_timestamp) as id_2,
max(server_name) keep (dense_rank last order by utc_timestamp) as server_name,
max(id_3) keep (dense_rank last order by utc_timestamp) as id_3,
max(count_1) keep (dense_rank last order by utc_timestamp) as count_1,
max(count_2) keep (dense_rank last order by utc_timestamp) as count_2
from table_name
where utc_timestamp > current_timestamp - interval '5' minute
and utc_timestamp <= current_timestamp
group by id_1
order by id_1;
查询按id_1分组，如您所希望的最新时间戳，max(utc_timestamp)为“正常”。其他列保留与id_的最大时间戳行相关联的值。
使用一些虚拟数据：
insert into table_name (id_1, utc_timestamp, id_2, server_name, id_3, count_1, count_2)
values (1, systimestamp at time zone 'UTC' - interval '30' second, 'TWC', 'test1', 301, 1, 1);
insert into table_name (id_1, utc_timestamp, id_2, server_name, id_3, count_1, count_2)
values (1, systimestamp at time zone 'UTC' - interval '60' second, 'TWC', 'test2', 302, 2, 2);
insert into table_name (id_1, utc_timestamp, id_2, server_name, id_3, count_1, count_2)
values (1, systimestamp at time zone 'UTC' - interval '90' second, 'TWC', 'test3', 303, 3, 3);
insert into table_name (id_1, utc_timestamp, id_2, server_name, id_3, count_1, count_2)
values (2, systimestamp at time zone 'UTC' - interval '45' second, 'TWC', 'test4', 304, 4, 4);
insert into table_name (id_1, utc_timestamp, id_2, server_name, id_3, count_1, count_2)
values (2, systimestamp at time zone 'UTC' - interval '15' second, 'TWC', 'test5', 305, 5, 5);
该查询获得结果：
ID_1 MAX(UTC_TIMESTAMP) ID_2 SERVE ID_3 COUNT_1 COUNT_2
---------- --------------------------- -------- ----- ---------- ---------- ----------
1 2017-07-21 18:38:22.944 UTC TWC test1 301 1 1
2 2017-07-21 18:38:38.399 UTC TWC test5 305 5 5
你可以通过更像你的尝试获得相同的结果：
with cte as (
select id_1, max(utc_timestamp) max_utc_timestamp
from table_name m
where utc_timestamp > current_timestamp - interval '5' minute
and utc_timestamp <= current_timestamp
group by id_1
)
select t.id_1, t.utc_timestamp, t.id_2, t.server_name, t.id_3, t.count_1, t.count_2
from cte
join table_name t on t.id_1 = cte.id_1
and t.utc_timestamp = cte.max_utc_timestamp
order by t.id_1;
...假设id_1和utc_timestamp组合是唯一的（不确定为什么使用id_2进行连接;可能这是唯一性所必需的？）。但这样效率会降低，因为它必须两次查询真实表，一次查找每个id_1的最大时间戳，然后再次在连接中查询。可能值得运行两个版本来比较结果和时间，以及执行计划。
使用您的示例数据（在2017-07-24更新），上面的第一个查询 - 仅修改为使用固定时间戳范围匹配 - 得到：
ID_1 MAX(UTC_TIMESTAMP) ID_ SERVER_NAME ID_3 COUNT_1 COUNT_2
---------- --------------------------------- --- ------------ ---------- ---------- ----------
1 2017-07-24 15:41:36.000000 +00:00 ABC PQRS.ABC.TPO 2 2 3
303 2017-07-24 15:41:55.000000 +00:00 ABC PQRS.ABC.TPO 2 4 0
1461 2017-07-24 15:42:48.000000 +00:00 ABC PQRS.ABC.TPO 2 1 7
或删除您似乎不感兴趣的列：
select id_1,
max(utc_timestamp),
max(count_1) keep (dense_rank last order by utc_timestamp) as count_1,
max(count_2) keep (dense_rank last order by utc_timestamp) as count_2
from table_name
where utc_timestamp > timestamp '2017-07-24 16:40:00 Europe/London' -- current_timestamp - interval '5' minute
and utc_timestamp <= timestamp '2017-07-24 16:45:00 Europe/London' -- current_timestamp
group by id_1
order by id_1;
ID_1 MAX(UTC_TIMESTAMP) COUNT_1 COUNT_2
---------- --------------------------------- ---------- ----------
1 2017-07-24 15:41:36.000000 +00:00 2 3
303 2017-07-24 15:41:55.000000 +00:00 4 0
1461 2017-07-24 15:42:48.000000 +00:00 1 7
然后进行下一步：
select max(max_utc_timestamp) as max_utc_timestamp,
sum(count_1) as sum_count_1,
sum(count_2) as sum_count_2
from (
select max(utc_timestamp) as max_utc_timestamp,
max(count_1) keep (dense_rank last order by utc_timestamp) as count_1,
max(count_2) keep (dense_rank last order by utc_timestamp) as count_2
from table_name
where utc_timestamp > timestamp '2017-07-24 16:40:00 Europe/London' -- current_timestamp - interval '5' minute
and utc_timestamp <= timestamp '2017-07-24 16:45:00 Europe/London' -- current_timestamp
group by id_1
);
MAX_UTC_TIMESTAMP SUM_COUNT_1 SUM_COUNT_2
--------------------------------- ----------- -----------
2017-07-24 15:42:48.000000 +00:00 7 10