Have you tried the code I sent you for PL/SQL - I think you will find this
works pretty well. I have used the approach I sent is fixing these kinds of
issues or very large datasets (in the billions).
I am happy to give additional guidance on PL/SQL offlist.
Brent
On Tue, May 31, 2016 at 10:34 AM, Ashoke Mandal <ramukam1983@xxxxxxxxx>
wrote:
Hi Scott, Lohar and Brent,
Thanks for your tips.
I have some questions before I try the insert method.
1. All three tables are partitioned by quarter with test_date. We have
data from 1992. The partitions were created from 1992 through 1996 by year
meaning there was only one partition for each year. But from 1997 through
2016 we have one partition for every quarter. So there are 85 partitions on
each of these tables. Both of the child tables contain multiple records
corresponding to each record on the master table.
2. For some reason even a simple select statement is taking long time on
each of these tables.
2.1 select count(*) from master_table; It takes 11 min => Records to be
updated in master_table: 2437461 (total records in this table is
222,760,096)
2.2 select count(*) from child_table_1; Takes 1 hour => Records to be
updated in child_table_1: 370569916 (total records in this table is
20,355,000,000)
2.3 select count(*) from child_table_2; Takes 3 hours => Records to be
updated in child_table_2: 4594843 (total records in this table is
1,843,018,199)
3. If I create a temporary copy of each of these tables using CTAS it
would create a regular table not the partitioned table. So I could generate
create script for each of these tables using TOAD or SQL Developer, then
expand 255 (85*3) tablespaces to it's double the size to host two copies of
these tables. I am kind of worried to touch these partitioned tables. If
something goes wrong then recovery of this 3TB database will be time
consuming.
Do you think there is some issue with my tables which is causing to take
the simple queries so long (as mentioned above)?
Could I speed up the update process using my PL/SQL code since that seems
safer as I don't need to touch the entire data and don't need to rebuild
index on 1 TB size of the biggest table.
Ashoke
On Sun, May 29, 2016 at 5:17 PM, Deas, Scott <Scott.Deas@xxxxxxx> wrote:
Ashoke,
I assume you have some sort of maintenance window allocated for this
work, so my recommendation would be to not do the update in place, but
rather to do something like the following:
1. CTAS for each table you’re changing to create an empty copy of
the table with the nologging option
2. Create a lookup table where you store original ut_id and new
ut_id
3. Parallel, direct path insert from original table (joining to
your control table to get the new ut_it) into new tables
4. Build all indexes/constraints
5. Verify data
6. Enable logging on tables/indexes
7. Rename objects so new tables now have the original table names
All of this assumes you aren’t changing in these objects.
You may also want to look at this whitepaper from Bryn Llewellyn that
discusses using PL/SQL to transform one table into another, when it’s
changing.
https://blogs.oracle.com/plsql-and-ebr/resource/Transforming_One_Table_to_Another_Sql_or_Plsql_Whitepaper.pdf
Thanks,
Scott
*From:* oracle-l-bounce@xxxxxxxxxxxxx [mailto:
oracle-l-bounce@xxxxxxxxxxxxx] *On Behalf Of *Ashoke Mandal
*Sent:* Sunday, May 29, 2016 5:42 PM
*To:* ORACLE-L <oracle-l@xxxxxxxxxxxxx>
*Subject:* Table update is taking too much time
Dear All, Let me know if you have any suggestions to make this update
faster as six days is too high.
Background: Due to some unexpected reason we have same set of test_ids in
the table for two different testing facilities. We are trying to change the
ut_ids of one facility to resolve the duplication issue using the following
code. It works but taking *6* days to complete the update and looking
for tips to make the update faster. The ut_id is part of the primary key in
all three tables (master_table, child_table_1 and child_table_2).
Records to be updated in master_table: 2437461 (total records in this
table is 222760096)
Records to be updated in child_table_1: 370569916
Records to be updated in child_table_2: 4594843
Using following UNIX shell script and a stored procedure:
*=> Calling shell script code:*
export PATH=$PATH:/opt/bin:/usr/ccs/bin:/usr/sbin:/var/opt/oracle
export DMAS_ROOT=/med_oracle/dmas/production
export start_utid=$1
export end_utid=$2
export ORACLE_SID=$3
# Set oracle environment for the specified database ($3)
export ORAENV_ASK=NO
. /usr/local/bin/oraenv
sqlplus user/password <<EOF1
-- Disable the Foreign key constraints on the child tables
ALTER TABLE CHILD_TABLE_1 DISABLE CONSTRAINT
CHILD_TABLE_1_FK_UT_ID_TEST_DATE;
ALTER TABLE CHILD_TABLE_2 DISABLE CONSTRAINT TEST_NOTE_FK_UT_ID_TEST_DATE;
TRUNCATE TABLE master_table_temp;
INSERT INTO master_table_temp select * from master_table where (ut_id>=
${start_utid} and ut_id <= ${end_utid}) and test_facility_code <> 'E';
-- Call the procedure to update the UT_Ids
EXECUTE proc_update_utid ('$1','$2');
-- Enable the foreign key constarints
ALTER TABLE CHILD_TABLE_1 ENABLE NOVALIDATE CONSTRAINT
child_table_1_FK_UT_ID_TEST_DATE;
ALTER TABLE TEST_NOTE ENABLE NOVALIDATE CONSTRAINT
child_table_2_FK_UT_ID_TEST_DATE;
EXIT;
EOF1
*=> Called stored procedure*
create or replace PROCEDURE proc_update_utid(start_utid number, end_utid
number) AS
lv_rec_count number :=0;
lv_update_number number :=0;
lv_total_rec_cnt number :=0;
lv_last_utid number;
lv_logfile varchar2(40);
lv_db_name varchar2(8);
lv_stmt varchar2(1000);
output_file UTL_FILE.FILE_TYPE;
-- Declare a cursor on the impacted records stored in the temporary
working table
cursor ut_cur is select * from master_table_temp order by ut_id;
begin
dbms_output.enable(10000000); -- setup of test output
-- Get the database name
select name into lv_db_name from v$database;
lv_logfile := lv_db_name || '_' || 'update.log';
output_file := UTL_FILE.FOPEN('/med_oracle/dmas/production/log',
lv_logfile, 'A');
utl_file.put_line(output_file,'Start Time: '|| to_char(sysdate,
'DD-MON-YYYY HH24:MI:SS'));
-- Check the number of duplicate UT_IDs to be updated
select count(*) into lv_total_rec_cnt from master_table
where (ut_id >= start_utid and ut_id <= end_utid) and test_facility_code
<> 'E';
utl_file.put_line(output_file,'Total number of duplicate UT_ID before the
update: '|| lv_total_rec_cnt);
--
for ur_rec in ut_cur
loop
-- dbms_output.put_line ('This is right before the update of
unit_test table');
update master_table set ut_id=ut_id+9000000000 where
ut_id=ur_rec.ut_id and
test_facility_code <> 'E';
-- dbms_output.put_line ('This is right before the update of
child_table_1 table');
update child_table_1 set ut_id=ut_id+9000000000 where
child_table_1.ut_id=ur_rec.ut_id and
test_date=ur_rec.test_date;
update child_table_2 set ut_id=ut_id+9000000000 where
child_table_2.ut_id=ur_rec.ut_id and
test_date=ur_rec.test_date;
test_date=ur_rec.test_date;
lv_rec_count := lv_rec_count+1;
if lv_rec_count = 1000
then
lv_update_number := lv_update_number+1;
-- insert a row to the update_status table
insert into update_status values(lv_update_number, ur_rec.ut_id,
sysdate);
commit;
lv_rec_count := 0;
else
lv_last_utid := ur_rec.ut_id;
end if;
end loop;
-- Following code is to address the last set of rows, which are less
than 1000.
if lv_rec_count != 1000
then
lv_update_number := lv_update_number+1;
-- insert a row to the update_status table
insert into update_status values(lv_update_number, lv_last_utid,
sysdate);
-- dbms_output.put_line ('This is right before the second commit');
commit;
end if;
-- Verify if the UT_ID between start_utid and end_utid range with
facility_code <> 'E' are
-- all assigned to a different UT_ID. If that is true then the following
query shouldn't return any row.
select count(*) into lv_total_rec_cnt from master_table
where (ut_id >= start_utid and ut_id <= end_utid) and test_facility_code
<> 'E';
dbms_output.put_line ('The total duplicate UT_IDs in master_table
is ' ||lv_total_rec_cnt);
--
utl_file.put_line(output_file,'Total number of duplicate UT_ID after the
update: '|| lv_total_rec_cnt);
utl_file.put_line(output_file,'End Time: '|| to_char(sysdate,
'DD-MON-YYYY HH24:MI:SS'));
utl_file.fclose(output_file);
end proc_update_utid;
Thanks,
Ashoke
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