Performance Tuning :: Explain Plan - %CPU Seems To Be Worse For JOIN Near Top?
Oct 24, 2011
however I was able to identify a poorly performing query that seemed to be maxing out our CPU. I have been trying to understand the Explain Plan. The plan below is from our test system which has considerably less information in the tables than our PROD system.
I can see there are a bunch of table scans at the end which may indicate missing indexes, but I am unclear on whether this is actually a problem as the %CPU seems to be worse for the JOIN near the top of the plan.
-------------------------------------------------------------------------------------------------------------------------------
| Id | Operation | Name | Rows | Bytes |TempSpc| Cost (%CPU)| Time | Inst |IN-OUT|
-------------------------------------------------------------------------------------------------------------------------------
| 0 | SELECT STATEMENT | | 1870M| 3018G| | 677M (1)|999:59:59 | | |
| 1 | SORT ORDER BY | | 1870M| 3018G| 3567G| 677M (1)|999:59:59 | | |
[code]...
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May 24, 2012
what privilege is require for a user to execute explain plan? I get below error while try to execute explain plan.
SQL> explain plan for SELECT /*+ FULL(t) */ COUNT(*) FROM "DREAM"."CONSUMER.TAB" t WHERE ROWNUM <= 1000000;
explain plan for SELECT /*+ FULL(t) */ COUNT(*) FROM "DREAM"."CONSUMER.TAB" t WHERE ROWNUM <= 1000000
*
ERROR at line 1:
ORA-01031: insufficient privileges
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Aug 17, 2012
I am facing a weird situation wherein the explain plan of same sql in SIT and PROD is different.In fact the explain plan is very costly in Prod.Also the DB version of both SIT and PROD is same.
Below is the sql and corresponding explain plan in Prod and SIT respectively.
Query:
SELECT seq,CCN,ProcessorPart,root_item,comp_path,Item,comp_item,comp_item_type,
lag(comp_item_type,1,'PART') over(PARTITION BY seq ORDER BY lvl)Nxt_comp_item_type,lvl,bom_qty,
ROUND(CASE min(abs(bom_qty)) OVER (PARTITION BY seq ORDER BY lvl)
WHEN 0 THEN 0 ELSE 1 END * EXP (SUM (LN (nullif(abs(bom_qty),0))) OVER (PARTITION BY seq ORDER BY lvl))) Ulti_qty,
'AMER'
[code]...
The tables referred in above query is small tables containing arnd 10k records.The above tables are partitioned on Region and not indexed.
Explain Plan in Prod: COST CARDINALITY BYTES
SELECT STATEMENT, GOAL = ALL_ROWS165173613539322883634804
SORT UNIQUE236360
UNION-ALL
PARTITION LIST SINGLE117240
[code]...
Explain Plan in SIT: COST CARDINALITY BYTES
SELECT STATEMENT, GOAL = ALL_ROWS3211689
SORT UNIQUE347240
UNION-ALL
PARTITION LIST SINGLE172120
[code]...
I am not able to attribute why there is a huge change in Cost between SIT and Prod.Apparently the Job is going for 3-5 hours which used to get completed within 20mins in SIT.
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Dec 14, 2010
I need to warn readers that I am not a DBA but am heavily involved in application development. Whatever I know about database tuning is whatever I've managed to pick up via self-learning, and I must admit that the sum total of my knowledge isn't a lot.
Anyway, our "DBAs" recently did an upgrade to our 10g database, going from version 10.2.0.2.0 to 10.2.0.4.0. Immediately after the upgrade, a particular query has started to under-perform. The query itself was not altered in any way during the upgrade.
We have two explain plans for the query, a before and an after plan. The two plans are similar but not identical. The plans are too massive to post here, so I hope the following synopsis of the differences will do.
The 10.2.0.2.0 plan:
shows a HASH GROUP BY
has a TempSpc column in the explain plan
shows a particular table (EMP_HISTORY) as having ~1700 rows
The 10.2.0.4.0 plan:
shows SORT GROUP BY instead of HASH GROUP BY does not show a TempSpc column in the explain plan shows the EMP_HISTORY table as having only 25 rows
Other than these points, no other discernible differences can be noted. I'm wondering what would cause HASH to change to SORT. I'm told that stats are up-to-date.
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Jul 21, 2010
I have two Oracle instances that are setup identically.When I run a query on one of them, it takes around 3 seconds, on the other it takes around 200 seconds.
I have looked at the explain plans, and it has shown me what I think is the problem. On one instance, it does a join on two tables, then runs the other filter/access predicates. On the other instance it runs the filter/access predicated first, then does the expensice join. The one that does the join first is the one that takes around 200 seconds. How to tell Oracle to make this join after runnning the other predicates?
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Aug 3, 2010
when i runnung the explain plan syntax , show error :
running --- SELECT * FROM TABLE(dbms_xplan.display) ;
ERROR: an uncaught error in function display has happened;
please contact Oracle support
Please provide also a DMP file of the used plan table
PLAN_TABLE
ORA-00904: "OTHER_TAG": 無效的 ID
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Dec 12, 2011
since the optimizer (during explain plan) assumes all bind variable to be of varchar type, while checking plan for SQL statement using bind variable of numeric and date type shall we convert (typecast) it as following?
variable n_sal number
variable dt_joining date
exec n_sal:= 1000
exec dt_joining := '12-dec-2005'
select first_name from emp_data where sal=to_number(n_sal) and joining=to_date(dt_joining);
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May 12, 2011
I have created an non unique index lk_fein on lookup_fein( code,map_id,trash). When I check the explain plan it does a full table scan on lookup_fein. if I force it to use index by it does and the cost also decreases.
SQL> SELECT WORK_FEIN,
2 NON_FEIN ,
3 FI_FEIN ,
4 MFEIN ,
5 TOTAL_FEIN ,
[code]...
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Jul 20, 2013
Why the query is behaving differently with the different database.(execution plan)
Whatever the production database is having same database instance replicated to a new schema. I tried both the queries running on both environment.In prod the index has been used but in newdev it is not. This case existing primary key index were not been used.
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Apr 12, 2013
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.
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Mar 25, 2012
I have queries on the execution plan of a sql statement
Following is the example
create table t1 as select s1.nextval id,a.* from dba_objects a;
create table t2 as select s2.nextval id,a.* from dba_objects a;
insert into t1 select s1.nextval id,a.* from dba_objects a;
insert into t1 select s1.nextval id,a.* from dba_objects a;
insert into t2 select s2.nextval id,a.* from dba_objects a;
insert into t2 select s2.nextval id,a.* from dba_objects a;
insert into t2 select s2.nextval id,a.* from dba_objects a;
commit;
create index i1 on t1(id);
create index i2 on t2(id);
create index i11 on t1(object_type);
exec dbms_stats.gather_table_stats(user,'T1',cascade=>true);
exec dbms_stats.gather_table_stats(user,'T2',cascade=>true);
select count(*) from t1 where object_type='VIEW';
COUNT(*)
----------
8934
set autotrace traceonly explain
Can we say in the following case, that,
(1) First index on object_type is accessed to get rowids - t1.object_type='VIEW'
(2) Then the filter on owner is applied - t1.owner='SYS'
(3) Then the table T1 is accessed to fetch data from the rowids returned by the index I11 and filer application - TABLE ACCESS BY INDEX ROWID
Though I am unable to understand how filter can be applied to the rowids retrieved from index, we can see from the plan below that The rows accessed have reduced from 8550 to 1221 before we access the table...Thus filter "t1.owner='SYS'" is applied in between. Right?
another question is
Case 1 - do we retrieve a rowid from index for a given value, then retrieve required values from table for that rowid
Thus row at a time in both ... in loop
OR
Case 2 - we first fetch all rowids from index and then retrieve values from table one row at a time from the collection of rowids fetched?
Suppose Case 1 is what is happening then can we say, both the steps mentioned by IDS 2,3 in plan below are executed exactly equal number of times and the filter "t1.owner='SYS'" is applied at some later stage? Of course in this case the values in ROWS stand misleading then
select * from t1,t2 where t1.id = t2.id and t1.object_type='VIEW' and t1.owner='SYS';
Execution Plan
----------------------------------------------------------
Plan hash value: 26873579
-------------------------------------------------------------------------------------
| Id | Operation | Name | Rows | Bytes | Cost (%CPU)| Time |
-------------------------------------------------------------------------------------
| 0 | SELECT STATEMENT | | 1221 | 233K| 915 (1)| 00:00:11 |
|* 1 | HASH JOIN | | 1221 | 233K| 915 (1)| 00:00:11 |
|* 2 | TABLE ACCESS BY INDEX ROWID| T1 | 1221 | 116K| 381 (1)| 00:00:05 |
|* 3 | INDEX RANGE SCAN | I11 | 8550 | | 24 (0)| 00:00:01 |
| 4 | TABLE ACCESS FULL | T2 | 161K| 15M| 533 (1)| 00:00:07 |
-------------------------------------------------------------------------------------
Predicate Information (identified by operation id):
---------------------------------------------------
1 - access("T1"."ID"="T2"."ID")
2 - filter("T1"."OWNER"='SYS')
3 - access("T1"."OBJECT_TYPE"='VIEW')
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Oct 31, 2012
So the situation is like this
- Database A (20 tables)
- Database B (20 tables)
- Both A and B are Oracle 11gR2
- Both of these databases run on different hardware (A is a VM, B is on a physical host)
- The 20 tables in A and B have exactly same number of rows and after preparing the data, the schemas were analysed using the same DBMS_STATS parameters
Despite this, the execution plans appear to be quite different for the same queries between A and B
I imagine there is something outside of the Oracle table rowcounts, table stats, column stats, index stats that's resulting in the different execution plans.
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Apr 30, 2012
refere to below 2 queries and their execution plans:
First Query
INSERT INTO temp_vendor(vendor_record_seq_no,checksum,rownumber,transaction_type,iu_flag)
SELECT /*+ USE_NL ( vd1 ,vd2 ,vd3 ) leading ( vd1 ,vd2 ,vd3 , tvd) */
vd1.vendor_record_seq_no, tvr.checksum, tvr.rownumber, tvr.transaction_type, 'U'
FROM vendor_data vd1,
[code]...
Second Query
SELECT vd1.vendor_record_seq_no, tvr.checksum, tvr.rownumber, tvr.transaction_type, 'U'
FROM ( select * from vendor_data vd1
where vd1.study_seq_no = 99903
AND vd1.control_column_seq_no = 435361232
[code]...
Both are to achieve same output but written in different ways. CAn I get same exectuion plan from 1st query as there is for 2nd using hints
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Jul 1, 2013
We have recently upgraded application (from Oracle Applications 11.5.9 to 12.1.3) and database (from 9.2.0.5.0 to 11.2.0.3.0).Since we are confronting to performances issues, i try to analyse some queries which Explains plans seems strange (in my opinion).Studying one of them i discover the next case (which according to my logic, i can't explain): --
Just bind variable --select *from MTL_MATERIAL_TRANSACTIONS mmtwhere 1 = 1and mmt.INVENTORY_ITEM_ID = :p1and mmt.ORGANIZATION_ID = :p2and mmt.TRANSACTION_REFERENCE = :p3--and mmt.SUBINVENTORY_CODE = :p4 PlanSELECT STATEMENT ALL_ROWS Cost: 5 Bytes: 361 Cardinality: 1 2 TABLE ACCESS BY INDEX ROWID TABLE INV.MTL_MATERIAL_TRANSACTIONS Cost: 5 Bytes: 361 Cardinality: 1 1 INDEX RANGE SCAN INDEX XXSPE.XXSPE_MTL_MATERIAL_TRANSAC_N99 Cost: 3 Cardinality: 2-- Nvl on bind variable --select *from MTL_MATERIAL_TRANSACTIONS mmtwhere 1 = 1and mmt.INVENTORY_ITEM_ID = :p1and
[code]...
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Mar 5, 2013
One of our clients is using Rule Based Optimizer on Oracle 10.2.0.3.0
2-3 weeks backs, during performance issue in one of the sql queries, one of our team members executed tuning adviser for it, created SQL profile and the subsequent execution of the SQL did not took much time (less I/O). Now it took hardly a minute to execute
When this happened I checked that the SQL profile forced that particular query to use CBO (say plan_hash_value is PHV1 here). Yesterday the same query again took 15-20 minutes for execution. I checked that even for this execution the query used the same SQL profile but "this time" with different plan_hash_value - say PHV2.
Today again the query executed in less than a minute and used the plan_hash_value as PHV1.
select distinct plan_hash_value,timestamp from dba_hist_sql_plan where sql_id='mysqlid' order by 1,2;
PLAN_HASH_VALUE TIMESTAMP
--------------- --------------------
890360113 20-feb-2013 16:38:39
3736413466 04-mar-2013 08:12:52
1237282258 03-jan-2013 17:15:02
I confirmed from awrsqrpt as well that different plans were used for different plan_hash_values and every time same SQL profile was used
SQL> select name,CATEGORY,SIGNATURE,CREATED,LAST_MODIFIED,TYPE,STATUS,FORCE_MATCHING from dba_sql_profiles;
NAME CATEGORY SIGNATURE CREATED LAST_MODIFIED TYPE STATUS FOR
------------------------------ ------------------------------ ---------- -------------------- -------------------- --------- -------- ---
SYS_SQLPROF_015ffffcc3e1c5b000 DEFAULT 1.5512E+19 20-feb-2013 16:30:48 20-feb-2013 16:30:48 MANUAL ENABLED NO
I am unable to understand how execution plan and thus plan_hash_value is changing for the same SQL Profile. I read that SQL Profile (unlike stored outline) keeps up with increasing data volume and may not keep up with changing data distribution.
I checked that values for 4 bind variables out of 81 are different for execution between today and yesterdays' run(queried v$sql_bind_capture based on last_captured)
My questions are
1) does the different plan_hash_values with different execution plans for query using same SQL profile mean the query was hard parsed multiple times and still used the same SQL profile?
2) If that is the case why I never saw child_number = 1 in any of the views for the same sql_id. I tried it repeatedly over last 2 weeks and always found child_number=0 in v$sql (also loaded_versions=1)
3) Does the different values of bind variable are causing this flip-flop of the plans? How can I conclude this?
I have 2 plans with 2 different plan_hash_values. I know which would be better. How can I force the sql to use better plan in the two in this case where I am using Rule Based Optimizer and have SQL profile created If this is not possible then how can I create stored outline from the existing plan (not waiting for subsequent execution to take place).
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Oct 29, 2013
The types of query I refer to in the title are of this pseudo-code ilk:
select t.column_value
from table1 o, xmltable('for $co in $data
where $co/path1=$bind1
and $co/path2=$bind2
passing o.field as "data", :b1 as "bind1", :b2 as "bind2") t
where o.field = :b3
They're querying a table with a (binary) xmltype with a path/domain index over this column.As those who have had the (mis)fortune to run into these will know, the queries are extensively rewritten under the covers to access to xml via the paths supplied.
getting a baseline to work with queries like this? I was suspicious because whilst I can hint it to pick a certain access path first (leading()), the plan hashes remain the same.
I'm not sure, however, if I'm simply "doing it wrong" or it is just not possible with the level of recursive rewriting going on.NB: I consider myself reasonably competent in applying baselines to "traditional" queries...
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Jul 3, 2009
How to find explain plan of a query in oracle using TOAD(any) and SQL Developer(any)?
If there any functional key to find out let me know.
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Feb 8, 2011
refer following sql statements and code
Session 1
create table tab1 as select * from dba_objects where object_id is not null;
alter session set events '10046 trace name context forever, level 12';
declare
x number;
begin
for i in 1..4
loop
[code]....
Session 2
after "starting" the above pl/sql block from Session 1, I keep on querying tab2 from Session 2 And as soon as 2 records are inserted in tab2, I create index from Session 2
select * from tab2;
select * from tab2;
select * from tab2;
N
----------
1
2
create index i on tab1(object_id);
As I have tested from a single session (just before this test) such index is used for the sql statement
select count(1) into x from tab1 where object_id=2331;
However when I checked the trace file I am not geeting results as expected
I am expecting 4 execution plans - 2 FTS and 2 Index Access scans and for this I am issuing following command
tkprof dst1_ora_7369.trc dst1_ora_7369.txt aggregate=no sys=no
But unfortunately I am getting following output
SELECT COUNT(1)
FROM
TAB1 WHERE OBJECT_ID=2331
call count cpu elapsed disk query current rows
------- ------ -------- ---------- ---------- ---------- ---------- ----------
Parse 1 0.00 0.00 0 1 0 0
Execute 4 0.00 0.00 0 2 0 0
[code]....
1) Why I am unable to see 4 execution plans - 2 with FTS and 2 with Index access when I mentioned 'aggregate=no'?
2) Whether the index i will be used for last 2 iterations after first 2 iterations of FTS?
If answer to above question 2) is 'No'
By which method I can force an ongoing sql statement in loop to take different execution path? Of course I can't hard parse sql in 'that' current session Will flushing Shared pool work in above case?
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May 18, 2010
Can we have same execution plan for a create table statement where the name of the table changes every time as follows:
create table test
as
select * from t1
Here table name changes from test to another table name next time
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Jun 4, 2010
The prod stats has been implemented in development. The stats has been gathered 2 months back on dev while in production the stats has been gathered 2 weeks back.
My question shouldn't the high volume of data causes changes in plan in both the environment? My thinking is that plan can be different as the high volume of data are changing in prod it may lead to a different plan.
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Sep 7, 2011
1. In previous version of Toad (9.7.2) during executing a statement I was able to click on 'Explain plan current statement'. In this version of Toad (10.6.0. 42) is not a possible to do it.In the Toad options I've filled the sign: "use a separate connection when Toad itself is generating transactions"
2. During executing a statement I still see 'clock' cursor.Is it a possible to disable to see it?
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Aug 16, 2012
I have an APP that truncates tables and loads data, which in turn makes the stats stale. I ran the query advisor (see attachment) and of course it ecommends running stats or accept a profile.I really don't want to do that as it may cause a load on my DB.
In turn, I would like to consider having my APP team change the query to pass a hint to use the best query plan.syntax to pass the hint to emulate good attached plan? Or is this a bad way to proceed?
select /* INDEX FAST FULL SCAN PK_PLACEMENT_REQUEST_QUEUE */
sum(lastshares) as "ROSEN"
from nyeo.fix_exec_reports fer, nyeo.placement_request_queue q,
nyeo.nyeo_block_control bc
where fer.clordid = q.sequence_number
and q.blockid = bc.blockid
and upper(bc.deskname) like '%ROSEN%'
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Jun 4, 2010
attached query giving consistent execution plan but different timings across run
SELECT /*+ INDEX (CRT CRT_CUN_FK_I)*/
DISTINCT odr.dve_id
FROM company_requirements crt, orders odr, lelo_products la_pct
WHERE crt.qtn_cun_id = 10035637--10000021--10035667
AND crt.ID = odr.crt_id_quote_implemented
AND NVL (odr.cancellation_date, '31-Dec-9999') = '31-Dec-9999'
[code]....
we have 4 databases, 2 on each servers, such that db1 and db2 on server1 and db3 and db4 on server2
refer count of the records for column of biggest table in the query, taken on all 4 databases (The column is nullable)
select count(*) from company_requirements crt WHERE crt.qtn_cun_id = 10035637
db1 = 73335
db2 = 89073
db3 = 81182
db4 = 82936
First I executed the query on db1 and db2 while there wasn't any user logged on to the system
db1
**********
call count cpu elapsed disk query current rows
------- ------ -------- ---------- ---------- ---------- ---------- ----------
Parse 1 0.06 0.08 0 0 0 0
Execute 1 0.00 0.00 0 0 0 0
Fetch 1 17.47 473.39 85704 1508102 0 0
[code]...
Elapsed times include waiting on following events:
Event waited on Times Max. Wait Total Waited
---------------------------------------- Waited ---------- ------------
SQL*Net message to client 1 0.00 0.00
db file sequential read 85704 0.31 460.55
latch free 1 0.00 0.00
SQL*Net message from client 1 14.98 14.98
[code]...
Why the elasped time changed when data and plan hasn't changed at all? Also why the plan has different stats for round 1 and 2 on db1 and db2?
I ran it 2 times each round each database so hard parsing shall not be issue.Also why the number of rows accessed are different in db1,db2 and db3,db4 especially for step1 when count of crt.qtn_cun_id is similar?
In fact when the query was taking long I was the only user on the system Also I used hard coded value (no bind variables at all)
I checked num_rows, distinct keys as well which are quite similar across all 4 databases Also no stats where gather during the query execution
What I should have checked or monitored?
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Jan 16, 2012
I have to do the optimization of a query that has the following characteristics:
- Takes 3 hours to process
- Performs the inner join with 30 tables
- Produces an output of 280 million records with 450 fields
First of all it is not feasible to make 30 updates (one for each table) to 280 million records.
The best solution that I had found so far was to create 3 temporary tables, where each of them to do the join with 1/3 of the 30 tables, and in the end I make the join between the main table and these three tables temporary.
I know that you will ask (or maybe not) to the query and samples, but it is impossible to create 30 examples.
how to optimize this type of querys that perform the join with multiple tables and produce a large output with (too) many columns.
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Dec 14, 2010
In SQL, almost all the thing which are possible with join is possible with sub-query also and vice-a-versa.
So when should I use sub-query and when should I go for join?
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Mar 14, 2012
For a hash join statement, is it beneficial to have the join condition objects in the index as well as the objects in the where clause?
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Mar 20, 2012
Which step in the following plan is the first step of execution
I reckon it is "TABLE ACCESS BY INDEX ROWID| BANK_BATCH_STATE"
Is that correct?
In the "Predicate Information (identified by operation id):"
section the predicates - access and filter for the step "TABLE ACCESS FULL | PYMNT_DUES" are displayed first
Isn't there any relation between the order of execution steps and the order in which predicates are displayed?
Execution Plan
----------------------------------------------------------
Plan hash value: 538700484
-------------------------------------------------------------------------------------------------------------
| Id | Operation | Name | Rows | Bytes | Cost (%CPU)| Time |
-------------------------------------------------------------------------------------------------------------
| 0 | SELECT STATEMENT | | 1 | 2364 | 15 (14)| 00:00:01 |
|* 1 | FILTER | | | | | |
| 2 | HASH GROUP BY | | 1 | 2364 | 15 (14)| 00:00:01 |
| 3 | NESTED LOOPS | | 1 | 2364 | 14 (8)| 00:00:01 |
| 4 | NESTED LOOPS | | 1 | 2313 | 13 (8)| 00:00:01 |
| 5 | NESTED LOOPS | | 1 | 2281 | 12 (9)| 00:00:01 |
| 6 | NESTED LOOPS OUTER | | 1 | 2255 | 11 (10)| 00:00:01 |
|* 7 | HASH JOIN | | 1 | 175 | 6 (17)| 00:00:01 |
|* 8 | INDEX RANGE SCAN | INDX_2 | 12 | 612 | 2 (0)| 00:00:01 |
|* 9 | TABLE ACCESS FULL | PYMNT_DUES | 43 | 5332 | 3 (0)| 00:00:01 |
| 10 | VIEW PUSHED PREDICATE | | 1 | 2080 | 5 (0)| 00:00:01 |
| 11 | NESTED LOOPS | | 1 | 154 | 5 (0)| 00:00:01 |
| 12 | NESTED LOOPS | | 1 | 103 | 4 (0)| 00:00:01 |
|* 13 | TABLE ACCESS BY INDEX ROWID| BANK_BATCH_STATE | 1 | 32 | 2 (0)| 00:00:01 |
|* 14 | INDEX RANGE SCAN | INDX_BBS_1 | 3 | | 1 (0)| 00:00:01 |
|* 15 | TABLE ACCESS BY INDEX ROWID| DAILY_CHECK | 1 | 71 | 2 (0)| 00:00:01 |
|* 16 | INDEX RANGE SCAN | INDX_SEARCH | 1 | | 1 (0)| 00:00:01 |
|* 17 | INDEX RANGE SCAN | INDX_2 | 1 | 51 | 1 (0)| 00:00:01 |
|* 18 | INDEX RANGE SCAN | INDX_IAM_SR_NO | 1 | 26 | 1 (0)| 00:00:01 |
|* 19 | INDEX RANGE SCAN | INDX_2 | 1 | 32 | 1 (0)| 00:00:01 |
|* 20 | INDEX RANGE SCAN | INDX_2 | 1 | 51 | 1 (0)| 00:00:01 |
-----------------------------------------------------------------
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Oct 14, 2013
I'm looking to see if there is a way (fully expecting it to be an underscore, or two...) to force the optimizer to keep churning until all permutations are exhausted.I'm aware that it, to paraphrase, cuts out when it's spent more time parsing than it would just running it based on it's estimates.
I've got some irritating problems with xml rewrite, xml indexes and access paths/cardinalities etc and I'm really needing the entire thing considered as a one off for debugging this. I've already cranked up the maximum permutations to the max but it's not enough, it shorts out after 5041 permutations (I'd set that to 80000 max).
I know you'd not want to do this in the real world but I cant get the damned thing to run the plan I want in a 10053 so I can see the values it has there. I know I can hint it, but I'm trying to ascertain why it's not even considering it in a "normal" parse.
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Nov 14, 2012
The product I work on requires a query to tell us what tables are dependent on certain types.
SELECT dba_tab_cols.owner,
dba_tab_cols.table_name,
dba_tab_cols.data_type_owner,
dba_tab_cols.data_type
FROM dba_tab_cols
JOIN dba_types
ON dba_types.owner = dba_tab_cols.data_type_owner
AND dba_types.type_name = dba_tab_cols.data_type
WHERE (dba_types.owner IN ('SCHEMA1', 'SCHEMA2'......))
I find this query to be pretty slow. I think it is because data_type_owner in dba_tab_cols is not indexed. Adding an index is not an option because users expect our product to read-only.
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Sep 12, 2011
Having production system: 11.2.0.1 on Windows Server x64
Test system: 9.2.0.1 on Windows XP
Problem preface: to get all unique CASEID which should be checked up by biometric system.What i should check - all CASEs for different PERSONs having same PHONEs at least among one phone type (1..4).Real table contains little bit more than 10 million records.I made test scripts.
Below the DDL for test table creation:
------------------------------------------
-- Create CASEINFO test table
------------------------------------------
DROP TABLE CASEINFO;
CREATE TABLE CASEINFO
[code]...
Below i've put SQL/DLL to make test data.number of records inserted 2 millions.
PERSON_COUNT := #/8;
------------------------------------------
-- fill CASEINFO with sample data
------------------------------------------
DECLARE
I INTEGER;
[code]...
Below SQL select to check the data in created table.
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-- Check test data counters
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SELECT 'TOTAL',count(*) from CASEINFO
UNION ALL
SELECT 'LEGAL',count(*) from CASEINFO where
[code]...
The PROBLEM is that i am experiencing HUGE perfomance problems on both test and production systems with that query:
select distinct b.caseid
from CASEINFO a, CASEINFO b
where (a.person<>b.person) and (a.sex=b.sex) and
(
(a.phone1=b.phone1) or
(a.phone1=b.phone2) or
(a.phone1=b.phone3) or
[code]...
This query takes almost 90 minutes to execute.And i do not know how to avoid this.Full SQL file to make test attached.
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