Table monitoring , how do oracle count the numbers ?

Question

hi,
i'm looking at all_tab_modifications , just couldn't figure out where those numbers from ,
DB.9208 , table partitioned
looks like it off of what it should be
my question is
1. when does montioring take place , and by how?
2. is the number cumulative from monitoring turn on ? from instance restart ? or between two snaps ?
3. offical doc says like inserts is Approximate number of inserts since the last time statistics were gathered
that means the number recycles after snap taken , it goes on by every DML , but i have insertions against a table which says inserts is 0
4. some says to reflect the newest exec dbms_stats.flush_database_monitoring_info; which is even more confusing for me and makes no difference in my case
thanks
TABLE_NAME                        INSERTS    UPDATES    DELETES TIME
T_GB_RA_PAGING                     0          0    2372389 20081125 005005
T_IU_OVERLOAD                      0          0          0 20081125 005005
T_RAUM                             0          0   13963245 20081125 005005
T_GB_SGSN_DATA                     0          0      33283 20081125 005005
T_IU_SGSN_DATA                     0          0          0 20081125 005005
T_SESSION_MANAGEMENT              82          0  386950042 20081125 005005
T_DATA                            82          0    1595707 20081125 005005
T_USER                            82          0     112562 20081125 005005
T_MOBILITY_MANAGEMENT             82          0  515890902 20081125 005005
T_DIPN                            82          0          0 20081125 005005
T_RAUM                         22409          0          0 20081125 103237
T_SESSION_MANAGEMENT          365547          0          0 20081125 103237Edited by: zs_hzh on Nov 24, 2008 10:35 PM

Answer 1

1. when does montioring take place , and by how?When you create a table, by default, it is set in MONITORING mode.
SQL> create table testtable as select * from all_objects where 1 = 2;
Table created.
SQL> select monitoring from user_tables where table_name='TESTTABLE';
MON
YES
2. is the number cumulative from monitoring turn on ? from instance restart ? or between two snaps ?http://download.oracle.com/docs/cd/B19306_01/server.102/b14237/statviews_2097.htm#i1591024
<quote>
ALL_TAB_MODIFICATIONS describes tables accessible to the current user that have been modified since the last time statistics were gathered on the tables.
<quote>
3. it goes on by every DML , but i have insertions against a table which says inserts is 0Is your table in MONITORING mode? If not, there will be no records in this view for that table.
4. some says to reflect the newest exec dbms_stats.flush_database_monitoring_info; which is even more confusing for me and makes no difference in my caseIt could be related to answer for #3.
Refer to this small demonstration.
SQL> execute dbms_stats.gather_table_stats(user,'TESTTABLE');
PL/SQL procedure successfully completed.
SQL> select * from all_tab_modifications where table_owner=USER and table_name='TESTTABLE';
no rows selected
SQL> insert into testtable select * from all_objects;
55958 rows created.
SQL> commit;
Commit complete.
SQL> select * from all_tab_modifications where table_owner=USER and table_name='TESTTABLE';
no rows selected
SQL> execute dbms_stats.flush_database_monitoring_info;
PL/SQL procedure successfully completed.
SQL> select table_name, inserts from all_tab_modifications where table_owner=USER and table_name='TESTTABLE';
TABLE_NAME                              INSERTS
TESTTABLE                                55,958
SQL> insert into testtable select * from all_objects;
55958 rows created.
SQL>  select table_name, inserts from all_tab_modifications where table_owner=USER and table_name='TESTTABLE';
TABLE_NAME                              INSERTS
TESTTABLE                                55,958
SQL> execute dbms_stats.flush_database_monitoring_info;
PL/SQL procedure successfully completed.
SQL>  select table_name, inserts from all_tab_modifications where table_owner=USER and table_name='TESTTABLE';
TABLE_NAME                              INSERTS
TESTTABLE                               111,916