Performance Tuning :: Lot Of Time Being Taken To Delete Data From A Table
Apr 27, 2012
I have a table which contains 8,21,177 amount of data totally.Now I am trying to delete around 4,84,000 of data from this table by using just one filter i.e. my query is something like below
DELETE /*+ parallel(resource,4) */ FROM resource where created_by = 'MIGN'
This is going to delete 4,84,000 rows of data . But my current issue is this is taking lots of time to delete the data . To be precise , its almost taking 25 hours to delete this data..The created_by column is indexed .
Execution Plan
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Plan hash value: 2389236532
| Id | Operation | Name | Rows | Bytes | Cost (%CPU)| Time
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In my code I am using delete statement which is taking too much time to execute.
Statement is as follow:
DELETE FROM TRADE_ORDER_EMP_ALLOCATION T WHERE (ARTEMIS_SOURCE_SYSTEM_ID,NM_ARTEMIS_SOURCE_SYSTEM,CD_BOOK_KEY,ACTIVITY_DT) IN (SELECT ARTEMIS_SOURCE_SYSTEM_ID,NM_ARTEMIS_SOURCE_SYSTEM,CD_BOOK_KEY,ACTIVITY_DT FROM LOAD_TRADE_ORDER WHERE IND_IS_BAD_RECORD='N');
Every column in "IN" clause and select clause is containing index on it
Every time no of rows which to be deleted is vary (May be in hundred ,thousand or hundred thousand )so that I am Unable to use "BITMAP" index on the table "LOAD_TRADE_ORDER" column "IND_IS_BAD_RECORD" though it is containing distinct record in it.
Even table "TRADE_ORDER_EMP_ALLOCATION" is containing "RANGE" PARTITION over it on the column "ARTEMIS_SOURCE_SYSTEM_ID". With this I am enclosing table scripts with Indexes and Partitions over it.
way for fast execution in of above delete statement?
I am using one script to delete the records from a table, its taking 1hr to delete.
declare cursor c1 is select ownerid,ownertype from nightly_metric_projects ; v1 c1%rowtype; open c1; loop fetch c1 into v1; exit when c1%notfound; DELETE FROM DGT_ITEMEFFORTDATA WHERE OWNERTYPE = c1.OWNERTYPE AND OWNERID = c1.OWNERID; end loop; close c1; commit;
nightly_metric_projects--1200 records DGT_ITEMEFFORTDATA--13200000
I need to check the package performance and need to improve the package performance.
1. how to check the package performance(each and every statement in the package)? 2. In the package using the delete statement to delete all records and observed that delete is taking long time to delete all the records in the table(Table records 7000000). This table is like staging table.Daily need to clean the data before inserting the data into it. what can I use instead of Delete.
I am running one simple delete statement in one table with rownum<10000 but it is taking nearly 10 to 15 mins.Table doesn't have any child table rows and triggers.
We have few tables in our production database which are havoc in size and will increase in size in future too so as part of the corrective measures , we have jotted down the below 3 methods to manage the size of those tables :-
1> Partitioning the table and take the export of identified partitions and after that, truncate those partition. 2> Creating history tables and remove not so current data from the original table to history table.
We are on Oracle 10.2.0.4 on Solaris 10. There is a table in my production db that has 872944 number of rows. Most of its data is now unnecessary, we need to retain, based on a date column in the table just last one month's data and delete rest of the data. So after that the table will have just 3000 rows.
However as the table was huge earlier(872k rows prior to delete) , does the delete of data release its oracle blocks and does the size of the table reduce? If not, will it rebuild the table online (online redefinition) so that the query that does a full scan on this table goes faster?
I checked using an example table that just delete of data does not remove the oracle blocks - they remain in the user_tables for that table and cost of full table scan remains same. We have a query that does the full table scan so I am thinking that after this delete I should do an online table re-definition , is that the right decision?
I am inserting data using a procedure for 2012 and 2013 year which is using partitioned tables includes crore of data in a partition taking lot of time or taking months. Is there any other way by which I can insert data fast from our query.
As per Article mentioned in Oracle Base,I have converted non-partitioned table (1 million data) into range-partition table,but,I don't see performance improvement in explain .
base on performance it is better to retrieve data from view or mention the table names directly?
I have a select statement in from clause one of my table is view (which is having data collected from four tables) my question is whether performance of querry will be improved if i use directly all tables( four tables of a view) instead of a view
How can i check the avg time taken by an execution plan. Actually i have a very big query and it changes its execution plan very often, we would like to lock the best execution plan and to find it , i would like to know the Average Execution Time the query takes when it runs using different different execution plans.
elapsed time = time spent on waits + time CPU was used
Total time during snaps = Elapsed time + (may be) time waited for CPU...In AWR is it possible to draw such equation? I can see that the AWR report has following elements
1) End Snap time - Begin Snap time 2) DB time - as mentioned at the top of AWR report 3) DB CPU - in "Top 5 Timed Foreground Events" (I assume this is 'CPU used by sesson timing' in statspack) 4) Total of time for all Statistics in "Time Model Statistics" 5) BUSY_TIME + IDLE_TIME - "Operating System Statistics"
Time between 2 snapshots? or what else? Also for which seconds to multiply to 'DB Time(s)' per second and 'DB CPU(s)' per second in Load Profile to get the db time and CPU time?
For example, we have a table ACCOUNT (snowflake dimension containing other dimension keys) and I have many fact tables based on this dimension. Normally data warehouse load happens like first dimensions needs to be loaded and then facts. Our frequency of loads is 30 mins.
To increase the rate in which the data will be available in the facts (as its a financial application), am considering to have two batches one with dimension and another one with fact (came to this conclusion as there is no dependency like first dimensions to be loaded then only fact) just the update might get missed sometimes. But if I do that, when dimension gets loaded, it will be read in the facts in another session. Will this affect the performance ?
LOADING (insert/update) and selecting data from table at the same time. Will it affect the performance in any way.
I understand that when data is read from the disk, I/O is done..And When computations are done then CPU is used..Then where the following equation fits?
On AWR, I see two script that are out of ordinary, and I want to make sure that I interpret them correctly.
1) "Elap per Exec (s)" shows 3263.49 with 1 "Executions". 2) "Elap per Exec (s)" shows 3180.17 each execution with 2 "Executions".
Does this mean that this script ran for ~ 54 minutes (3263.49 / 60 seconds) for 1 "Execution" and ~ 53 minutes (3180.17 / 60 seconds) per each execution? I need to understand "Elapsed Time (s),CPU Time (s),Executions ,Elap per Exec (s), % Total DB Time" represent.
- First time to execute: Using all indexes on 2 tables
- Second time to execute: Using only indexes on first table, full table scan on the other
- Third time to execute: Do FTS on both of tables.
Now, I show the objects and relate information here:
The Tables:
system@dbwap> select count(*) from my_wap.news_relation;
COUNT(*) ---------- 272708
system@dbwap> select count(*) from my_wap.news_content;
COUNT(*) ---------- 95092
system@dbwap> desc my_wap.news_content; Name Null? Type ----------------------------------------------------- -------- ---------------- ID NOT NULL NUMBER(11) SUBJECT NOT NULL VARCHAR2(500) TITLE VARCHAR2(4000) STATE NUMBER(1) IMGPATH VARCHAR2(500) ALIGN VARCHAR2(10)
Yesterday, there were performance issue at server. So today, when i am generating report for that particular period, found snapshot id sequence is serially but with skipped hourly timed. Instead of generating report at 15:30, it generated at 16:30.
Enter value for num_days: 2
Listing the last 2 days of Completed Snapshots Snap Instance DB Name Snap Id Snap Started Level ------------ ------------ --------- ------------------ ----- tagidev TAGIDEV 2857 10 Sep 2013 00:30 1 2858 10 Sep 2013 01:30 1 2859 10 Sep 2013 02:30 1 2860 10 Sep 2013 03:30 1 2861 10 Sep 2013 04:30 1 2862 10 Sep 2013 05:31 1
[code]....
Below are the details at alert log -
Tue Sep 10 14:28:20 2013 Thread 1 cannot allocate new log, sequence 7029 Checkpoint not complete Current log# 2 seq# 7028 mem# 0: E:APPORACLEORADATATAGIDEVREDO02.LOG Thread 1 advanced to log sequence 7029 (LGWR switch)
[code]....
1) why snap didn't started at 15:30?
2) since database just started at the scheduled time of AWR snap time. But generated at 16:32 instead of 16:30, though last services "SMCO" is started at 16:42. How it snap id generated for this particular time?
3) what does "kewastUnPackStats(): bad magic 1 (0x000000001B3CE48D, 0)" mean?
Is there any way to reduce the index creation time. I have one table which has 7700000 records and every day this table get truncate and we create with create table as select statement and then create the 4 indexes and each index took 5 minutes so in totality it took 20 minutes in index creation.
Elapsed Time (s) CPU Time (s) Executions Elap per Exec (s) % Total DB Time SQL Id SQL Module SQL Text 2,423 1 3,919 0.62 1.83 gt49gg0fnc5x8 srv_dr@ahs (TNS V1-V3) UPDATE /*+ CCL<OENDB_FILE... 2,227 14 1 2227.16 1.68 bggfx8a04prj9 SQL*Plus select * from (select n.source... .........
On [SQL ordered by Elapsed Time], [SQL Module] shows an indication that a SQL was executed by which process (i.e. srv_dr@ahs)outside of SQL*PLUS.If [SQL Modeule] shows as [SQL*Plus], does it mean the query was run in SQL*PLUS manually or directly?I have the SQL ID. How do I find out who, how, and exactly what time it was run?
In my insert query, Window sort takes longer time i.e. 93% of total execution time, How do i reduce this time? are there any tuning parameters availabe for this?
I have a Query(report) which is running in <5 mins in one Scheme, where as the same is running for a long time in second schema. I have identified that an Index is scanning for more than 2000 Millions of records in second Schema, but this is scanning only 440 Millions in First Schema and hence it is fast. I am expecting the same to be done in Second schema.
I have verified the following All records in tables in 2 schemas are same. All indexes are same Analyzed the tables Gathered Histogram on all the columns as per the first schema.
But now i still have the same problem, don't know what could be the problem.
I executed a query which executed quickly (1.7 seconds) but since its output took time in displaying on the console the time shown by 'set timing on was 39.5 seconds
also I took trace (tkprof) for the same.My query is why the timings under 'Total Waited' (43.19 and 1.69) are not added to the elapsed time 1.83 seconds
here we have an scenario where we want to find out all the sql statements that are executed in a particular time. The sql statements are executed via our application. I tried in awr report but it shows only the sql query which has taken long time to execute. and i even tried in V$session and V$sqlarea. how to view the executed sql statements in a particular session/current session
We have a big hierarchical query which is now running for a long time (around 6 hours. earlier it was running for 3 hours). We have to tune this query so that we run the jobs within a stipulated time frame.
The query below inserts around 42 million records in to the table WK_ACCT_WSTORE. I have attached in the text file.
