Oracle 18c

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create table logs (id number, log_tags varchar2(4000));
begin
    insert into logs (id, log_tags) values ( 1,'<Event time="Sat Apr 15 1:13:17.750" type="Debug" thread="2fec: Main CIM worker thread" elapsed="0" ');
    insert into logs (id, log_tags) values ( 2,'Database: C:\2023 Files\GDBs_4\New Mobile Geodatabase.geodatabase');
    insert into logs (id, log_tags) values ( 3,'      SQL: SELECT main.ACTIVE_TRANSPORTATION.OBJECTID,main.active_transportation_nt_flag_vw.flag FRO');
    insert into logs (id, log_tags) values ( 4,'</Event>');
    
    insert into logs (id, log_tags) values ( 5,'<Event time="Sat Apr 15 1:13:17.749" type="Debug" thread="2fec: Main CIM worker thread" elapsed="1" ');
    insert into logs (id, log_tags) values ( 6,null);
    insert into logs (id, log_tags) values ( 7,'</Event>');
    
    insert into logs (id, log_tags) values ( 8,'<Event time="Sat Apr 15 1:13:17.749" type="Debug" thread="2fec: Main CIM worker thread" elapsed="2" ');
    insert into logs (id, log_tags) values ( 9,'Database: C:\2023 Files\GDBs_4\New Mobile Geodatabase.geodatabase');
    insert into logs (id, log_tags) values (10,'      SQL: SELECT main.ACTIVE_TRANSPORTATION.OBJECTID,main.active_transportation_nt_flag_vw.flag FRO');
    insert into logs (id, log_tags) values (11,'      Number of features returned: 100');
    insert into logs (id, log_tags) values (12,'</Event>');
    
    insert into logs (id, log_tags) values (13,'<Event time="Sat Apr 15 1:13:17.749" type="Debug" thread="2fec: Main CIM worker thread" elapsed="0" ');
    insert into logs (id, log_tags) values (14,null);
    insert into logs (id, log_tags) values (15,'</Event>');
    
    insert into logs (id, log_tags) values (16,'<Event time="Sat Apr 15 1:13:17.747" type="Debug" thread="2fec: Main CIM worker thread" elapsed="0" ');
    insert into logs (id, log_tags) values (17,'Database: C:\2023 Files\GDBs_4\New Mobile Geodatabase.geodatabase');
    insert into logs (id, log_tags) values (18,'      SQL: SELECT main.ACTIVE_TRANSPORTATION.OBJECTID,main.active_transportation_nt_flag_vw.flag FRO');
    insert into logs (id, log_tags) values (19,'</Event>');
    
    insert into logs (id, log_tags) values (20,'<Event time="Sat Apr 15 1:13:17.747" type="Debug" thread="2fec: Main CIM worker thread" elapsed="2" ');
    insert into logs (id, log_tags) values (21,'Database: C:\2023 Files\GDBs_4\New Mobile Geodatabase.geodatabase');
    insert into logs (id, log_tags) values (22,'      SQL: SELECT main.ACTIVE_TRANSPORTATION.OBJECTID,main.active_transportation_nt_flag_vw.flag FRO');
    insert into logs (id, log_tags) values (23,'      Number of features returned: 100');
    insert into logs (id, log_tags) values (24,'</Event>');
    
    insert into logs (id, log_tags) values (25,'<Event time="Sat Apr 15 1:13:17.746" type="Debug" thread="2fec: Main CIM worker thread" elapsed="1" ');
    insert into logs (id, log_tags) values (26,null);
    insert into logs (id, log_tags) values (27,'</Event>');
    
    insert into logs (id, log_tags) values (28,'<Event time="Sat Apr 15 1:13:17.746" type="Debug" thread="2fec: Main CIM worker thread" elapsed="0" ');
    insert into logs (id, log_tags) values (29,null);
    insert into logs (id, log_tags) values (30,'</Event>');
    
    insert into logs (id, log_tags) values (31,'<Event time="Sat Apr 15 1:13:17.744" type="Debug" thread="2fec: Main CIM worker thread" elapsed="0" ');
    insert into logs (id, log_tags) values (32,'Database: C:\2023 Files\GDBs_4\New Mobile Geodatabase.geodatabase');
    insert into logs (id, log_tags) values (33,'      SQL: SELECT main.ACTIVE_TRANSPORTATION.OBJECTID,main.active_transportation_nt_flag_vw.flag FRO');
    insert into logs (id, log_tags) values (34,'</Event>');
    
    insert into logs (id, log_tags) values (35,'<Event time="Sat Apr 15 1:13:17.743" type="Debug" thread="2fec: Main CIM worker thread" elapsed="1" ');
    insert into logs (id, log_tags) values (36,null);
    insert into logs (id, log_tags) values (37,'</Event>');
end;
/
1 rows affected

select 1 + sum(case when log_tags = '</Event>' then 1 else 0 end) over (order by id) 
  - case when log_tags = '</Event>' then 1 else 0 end as GROUP_ID,
  log_tags
from logs


GROUP_ID
LOG_TAGS


1
<Event time="Sat Apr 15 1:13:17.750" type="Debug" thread="2fec: Main CIM worker thread" elapsed="0"

1
Database: C:\2023 Files\GDBs_4\New Mobile Geodatabase.geodatabase

1
      SQL: SELECT main.ACTIVE_TRANSPORTATION.OBJECTID,main.active_transportation_nt_flag_vw.flag FRO

1
</Event>

2
<Event time="Sat Apr 15 1:13:17.749" type="Debug" thread="2fec: Main CIM worker thread" elapsed="1"

2
null

2
</Event>

3
<Event time="Sat Apr 15 1:13:17.749" type="Debug" thread="2fec: Main CIM worker thread" elapsed="2"

3
Database: C:\2023 Files\GDBs_4\New Mobile Geodatabase.geodatabase

3
      SQL: SELECT main.ACTIVE_TRANSPORTATION.OBJECTID,main.active_transportation_nt_flag_vw.flag FRO

3
      Number of features returned: 100

3
</Event>

4
<Event time="Sat Apr 15 1:13:17.749" type="Debug" thread="2fec: Main CIM worker thread" elapsed="0"

4
null

4
</Event>

5
<Event time="Sat Apr 15 1:13:17.747" type="Debug" thread="2fec: Main CIM worker thread" elapsed="0"

5
Database: C:\2023 Files\GDBs_4\New Mobile Geodatabase.geodatabase

5
      SQL: SELECT main.ACTIVE_TRANSPORTATION.OBJECTID,main.active_transportation_nt_flag_vw.flag FRO

5
</Event>

6
<Event time="Sat Apr 15 1:13:17.747" type="Debug" thread="2fec: Main CIM worker thread" elapsed="2"

6
Database: C:\2023 Files\GDBs_4\New Mobile Geodatabase.geodatabase

6
      SQL: SELECT main.ACTIVE_TRANSPORTATION.OBJECTID,main.active_transportation_nt_flag_vw.flag FRO

6
      Number of features returned: 100

6
</Event>

7
<Event time="Sat Apr 15 1:13:17.746" type="Debug" thread="2fec: Main CIM worker thread" elapsed="1"

7
null

7
</Event>

8
<Event time="Sat Apr 15 1:13:17.746" type="Debug" thread="2fec: Main CIM worker thread" elapsed="0"

8
null

8
</Event>

9
<Event time="Sat Apr 15 1:13:17.744" type="Debug" thread="2fec: Main CIM worker thread" elapsed="0"

9
Database: C:\2023 Files\GDBs_4\New Mobile Geodatabase.geodatabase

9
      SQL: SELECT main.ACTIVE_TRANSPORTATION.OBJECTID,main.active_transportation_nt_flag_vw.flag FRO

9
</Event>

10
<Event time="Sat Apr 15 1:13:17.743" type="Debug" thread="2fec: Main CIM worker thread" elapsed="1"

10
null

10
</Event>

GROUP_ID	LOG_TAGS
1	<Event time="Sat Apr 15 1:13:17.750" type="Debug" thread="2fec: Main CIM worker thread" elapsed="0"
1	Database: C:\2023 Files\GDBs_4\New Mobile Geodatabase.geodatabase
1	SQL: SELECT main.ACTIVE_TRANSPORTATION.OBJECTID,main.active_transportation_nt_flag_vw.flag FRO
1	</Event>
2	<Event time="Sat Apr 15 1:13:17.749" type="Debug" thread="2fec: Main CIM worker thread" elapsed="1"
2	null
2	</Event>
3	<Event time="Sat Apr 15 1:13:17.749" type="Debug" thread="2fec: Main CIM worker thread" elapsed="2"
3	Database: C:\2023 Files\GDBs_4\New Mobile Geodatabase.geodatabase
3	SQL: SELECT main.ACTIVE_TRANSPORTATION.OBJECTID,main.active_transportation_nt_flag_vw.flag FRO
3	Number of features returned: 100
3	</Event>
4	<Event time="Sat Apr 15 1:13:17.749" type="Debug" thread="2fec: Main CIM worker thread" elapsed="0"
4	null
4	</Event>
5	<Event time="Sat Apr 15 1:13:17.747" type="Debug" thread="2fec: Main CIM worker thread" elapsed="0"
5	Database: C:\2023 Files\GDBs_4\New Mobile Geodatabase.geodatabase
5	SQL: SELECT main.ACTIVE_TRANSPORTATION.OBJECTID,main.active_transportation_nt_flag_vw.flag FRO
5	</Event>
6	<Event time="Sat Apr 15 1:13:17.747" type="Debug" thread="2fec: Main CIM worker thread" elapsed="2"
6	Database: C:\2023 Files\GDBs_4\New Mobile Geodatabase.geodatabase
6	SQL: SELECT main.ACTIVE_TRANSPORTATION.OBJECTID,main.active_transportation_nt_flag_vw.flag FRO
6	Number of features returned: 100
6	</Event>
7	<Event time="Sat Apr 15 1:13:17.746" type="Debug" thread="2fec: Main CIM worker thread" elapsed="1"
7	null
7	</Event>
8	<Event time="Sat Apr 15 1:13:17.746" type="Debug" thread="2fec: Main CIM worker thread" elapsed="0"
8	null
8	</Event>
9	<Event time="Sat Apr 15 1:13:17.744" type="Debug" thread="2fec: Main CIM worker thread" elapsed="0"
9	Database: C:\2023 Files\GDBs_4\New Mobile Geodatabase.geodatabase
9	SQL: SELECT main.ACTIVE_TRANSPORTATION.OBJECTID,main.active_transportation_nt_flag_vw.flag FRO
9	</Event>
10	<Event time="Sat Apr 15 1:13:17.743" type="Debug" thread="2fec: Main CIM worker thread" elapsed="1"
10	null
10	</Event>