Finding the Text of SQL Query causing Full Table Scans

Hi,
does anyone have a sql script, that shows the complete sql text of queries that have caused a full table scan?
Please also let me know as to how soon this script needs to be run, in the sense does it work only while the query is running or would it work once it completes (if so is there a valid duration, such as until next restart, etc.)
Your help is appreciated.
Thx,
Mayuran

Finding the Text of SQL Query Causing Full Table Scan

Similar Messages

Finding the Text of SQL Query Causing Full Table Scan

Hi,
does anyone have a sql script, that shows the complete sql text of queries that have caused a full table scan?
Please also let me know as to how soon this script needs to be run, in the sense does it work only while the query is running or would it work once it completes (if so is there a valid duration, such as until next restart, etc.)
Your help is appreciated.
Thx,
Mayuran

You might try something like this:
select sql_text,
       object_name
from   v$sql s,
       v$sql_plan p
where s.address = p.address and
       s.hash_value = p.hash_value and
       s.child_number = p.child_number and
       p.operation = 'TABLE ACCESS' and
       p.options = 'FULL' and
       p.object_owner in ('SCOTT')
;Please note that this query is just a snapshot of the SQL statements currently in the cache.

SQL Performance causing full table scan

I have this SQL:
SELECT DISTINCT
UPPER (RTRIM (LTRIM (SS.PRESCDEAID))) PRESCRIBER,
UPPER (RTRIM (LTRIM (SS.NPIPRESCR))) NPI_NUMBER
FROM
PBM_SXC_STAGING SS,
PBM_PHYSICIANS P
WHERE
P.PHYSICIAN_ID = SS.PRESCDEAID
AND P.NPI_NUMBER <> SS.NPIPRESCR
AND SS.NPIPRESCR <> SS.PRESCDEAID
Uses this plan:
SELECT STATEMENT ALL_ROWSCost: 13,843 Bytes: 3,636,232 Cardinality: 106,948
     4 SORT UNIQUE Cost: 13,843 Bytes: 3,636,232 Cardinality: 106,948
          3 HASH JOIN Cost: 12,866 Bytes: 3,636,232 Cardinality: 106,948
               1 TABLE ACCESS FULL TABLE PBM.PBM_PHYSICIANS Cost: 4,156 Bytes: 17,639,063 Cardinality: 1,356,851
               2 INDEX FAST FULL SCAN INDEX PBM.SXCSTG_IDX1 Cost: 3,859 Bytes: 43,302,882 Cardinality: 2,062,042
If I comment out "AND P.NPI_NUMBER <> SS.NPIPRESCR" I get this plan that uses the PK index (PBM.PBM_PHYSICIAN_PK) that is on P.PHYSICIAN_ID. I do have an index on P.NPI_NUMBER
SELECT STATEMENT ALL_ROWSCost: 27,230 Bytes: 64,514,496 Cardinality: 2,016,078
     4 SORT UNIQUE Cost: 27,230 Bytes: 64,514,496 Cardinality: 2,016,078
          3 HASH JOIN Cost: 9,617 Bytes: 64,514,496 Cardinality: 2,016,078
               1 INDEX FAST FULL SCAN INDEX (UNIQUE) PBM.PBM_PHYSICIAN_PK Cost: 1,035 Bytes: 14,925,361 Cardinality: 1,356,851
               2 INDEX FAST FULL SCAN INDEX PBM.SXCSTG_IDX1 Cost: 3,859 Bytes: 43,302,882 Cardinality: 2,062,042

Sorry for the delay, I was out of the office.
PLAN_TABLE_OUTPUT
SQL_ID 4j270u8fbhwpu, child number 0
SELECT /*+ gather_plan_statistics */          DISTINCT          upper
(rtrim (ltrim (ss.prescdeaid))) prescriber         ,upper (rtrim (ltrim
(ss.npiprescr))) npi_number FROM pbm_sxc_staging ss     ,pbm_physicians
p WHERE p.physician_id = ss.prescdeaid   AND p.npi_number !=
ss.npiprescr   AND ss.npiprescr != ss.prescdeaid
Plan hash value: 2275909877
PLAN_TABLE_OUTPUT
| Id | Operation              | Name           | Starts | E-Rows | A-Rows |   A-Time   | Buffers | Reads | OMem | 1Mem | Used-Mem |
|   1 | HASH UNIQUE           |                |      1 |    125K|     68 |00:00:01.54 |   24466 | 14552 | 1001K| 1001K| 1296K (0)|
|* 2 |   HASH JOIN            |                |      1 |    125K|   6941 |00:00:01.14 |   24466 | 14552 |    47M| 6159K|   68M (0)|
|   3 |    TABLE ACCESS FULL   | PBM_PHYSICIANS |      1 |   1341K|   1341K|00:00:00.01 |   14556 | 14552 |       |       |          |
|* 4 |    INDEX FAST FULL SCAN| SXCSTG_IDX1    |      1 |   1872K|   1887K|00:00:00.01 |    9910 |   0 |          |       |          |
Predicate Information (identified by operation id):
PLAN_TABLE_OUTPUT
   2 - access("P"."PHYSICIAN_ID"="SS"."PRESCDEAID")
       filter("P"."NPI_NUMBER"<>"SS"."NPIPRESCR")
   4 - filter("SS"."NPIPRESCR"<>"SS"."PRESCDEAID")Edited by: Chris on Jul 12, 2011 8:19 AM

How can this query avoid full table scans?

It is difficult to avoid full table scans in the following query because the values of column STATUS reiterant numbers. There are only 10 numbers values for the STATUS column (1..10)
But the table is very large. there are more than 1 million rows in it. A full table scanning consumes too much time.
How can this query avoid full table scans?
Thank you
SELECT SYNC,CUS_ID INTO V_SYNC,V_CUS_ID FROM CONSUMER_MSG_IDX
                  WHERE CUS_ID = V_TYPE_CUS_HEADER.CUS_ID AND
                        ADDRESS_ID = V_TYPE_CUS_HEADER.ADDRESS_ID AND
                        STATUS =! 8;Edited by: junez on Jul 23, 2009 7:30 PM

Your code had an extra AND. I also replaced the "not equal" operator, which has display problems with the forum software
SELECT SYNC,CUS_ID
   INTO V_SYNC,V_CUS_ID
FROM CONSUMER_MSG_IDX
WHERE CUS_ID = V_TYPE_CUS_HEADER.CUS_ID AND
       ADDRESS_ID = V_TYPE_CUS_HEADER.ADDRESS_ID AND
       STATUS != 8;Are you sure this query is doing a table scan? Is there an index on CUS_ID, ADDRESS_ID? I would think that would be mostly unique. So I'm not sure why you think the STATUS column is causing problems. It would seem to just be a non-selective additional filter.
Justin

Locate SQL causes full table scans from Statspack

Hello,
In my statspack reports I see a lot of full tables scans (1,425,297)
How can I locate the query that causes this ?
stats$sql_plan should fit?
Oracle is 9i
Thank you

>
How can I locate the query that causes this ?
It can be hard. One idea is to put comments in queries identifying where they come from, something like
select /* my_package.my_procedure */ *
from dual;
[/code
The comment should remain with the sql text so various reports showing the sql text should also indicate where the query is]

Simple Query in Oracle Linked Table in MS Access causes full table scan.

I am running a very simple query in MS ACCESS to a linked Oracle table as follows:
Select *
From EXPRESS_SERVICE_EVENTS --(the linked table name refers to EXPRESS.SERVICE_EVENTS)
Where performed > MyDate()
or
Select *
From EXPRESS_SERVICE_EVENTS --(the linked table name refers to EXPRESS.SERVICE_EVENTS)
Where performed > [Forms]![MyForm]![Date1]
We have over 50 machines and this query runs fine on over half of these, using an Oracle Index on the "performed" field. Running exactly the same thing on the other machines causes a full table scan, therefore ignoring the Index (all machines access the same Access DB).
Strangely, if we write the query as follows:
Select *
From EXPRESS_SERVICE_EVENTS
Where performed > #09/04/2009 08:00#
it works fast everywhere!
Any help on this 'phenominon' would be appreciated.
Things we've done:
Checked regional settings, ODBC driver settings, MS Access settings (as in Tools->Options), we have the latest XP and Office service packs, and re-linked all Access Tables on both the slow and fast machines independantly).

Primarily, thanks gdarling for your reply. This solved our problem.
Just a small note to those who may be using this thread.
Although this might not be the reason, my PC had Oracle 9iR2 installed with Administratiev Tools, where user machines had the same thing installed but using Runtime Installation. For some reason, my PC did not have 'bind date' etc. as an option in the workarounds, but user machines did have this workaround option. Strangely, although I did not have the option, my (ODBC) query was running as expected, but user queries were not.
When we set the workaround checkbox accordingly, the queries then run as expected (fast).
Once again,
Thanks

Entity Framework Generated SQL for paging or using Linq skip take causes full table scans.

The slq genreated creates queries that cause a full table scan for pagination. Is there any way to fix this?
I am using
ODP.NET ODTwithODAC1120320_32bit
ASP.NET 4.5
EF 5
Oracle 11gR2
This table has 2 million records. The further into the records you page the longer it takes.
LINQ
var cnt = (from errorLog in ctx.ERRORLOGANDSERVICELOG_VIEW
                    select errorLog).Count();
                var query = (from errorLog in ctx.ERRORLOGANDSERVICELOG_VIEW
                             orderby errorLog.ERR_LOG_ID
                             select errorLog).Skip(cnt-10).Take(10).ToList();
Here is the query & execution plans.
SELECT *
FROM   (SELECT "Extent1"."ERR_LOG_ID" AS "ERR_LOG_ID",
               "Extent1"."SRV_LOG_ID" AS "SRV_LOG_ID",
               "Extent1"."TS"          AS "TS",
               "Extent1"."MSG"         AS "MSG",
               "Extent1"."STACK_TRACE" AS "STACK_TRACE",
               "Extent1"."MTD_NM"      AS "MTD_NM",
               "Extent1"."PRM"         AS "PRM",
               "Extent1"."INSN_ID"     AS "INSN_ID",
               "Extent1"."TS_1"        AS "TS_1",
               "Extent1"."LOG_ETRY"    AS "LOG_ETRY"
        FROM   (SELECT "Extent1"."ERR_LOG_ID"                                  AS "ERR_LOG_ID",
                       "Extent1"."SRV_LOG_ID"                                  AS "SRV_LOG_ID",
                       "Extent1"."TS"                                          AS "TS",
                       "Extent1"."MSG"                                         AS "MSG",
                       "Extent1"."STACK_TRACE"                                 AS "STACK_TRACE",
                       "Extent1"."MTD_NM"                                      AS "MTD_NM",
                       "Extent1"."PRM"                                         AS "PRM",
                       "Extent1"."INSN_ID"                                     AS "INSN_ID",
                       "Extent1"."TS_1"                                        AS "TS_1",
                       "Extent1"."LOG_ETRY"                                    AS "LOG_ETRY",
                       row_number() OVER (ORDER BY "Extent1"."ERR_LOG_ID" ASC) AS "row_number"
                FROM   (SELECT "ERRORLOGANDSERVICELOG_VIEW"."ERR_LOG_ID" AS "ERR_LOG_ID",
                               "ERRORLOGANDSERVICELOG_VIEW"."SRV_LOG_ID" AS "SRV_LOG_ID",
                               "ERRORLOGANDSERVICELOG_VIEW"."TS"          AS "TS",
                               "ERRORLOGANDSERVICELOG_VIEW"."MSG"         AS "MSG",
                               "ERRORLOGANDSERVICELOG_VIEW"."STACK_TRACE" AS "STACK_TRACE",
                               "ERRORLOGANDSERVICELOG_VIEW"."MTD_NM"      AS "MTD_NM",
                               "ERRORLOGANDSERVICELOG_VIEW"."PRM"         AS "PRM",
                               "ERRORLOGANDSERVICELOG_VIEW"."INSN_ID"     AS "INSN_ID",
                               "ERRORLOGANDSERVICELOG_VIEW"."TS_1"        AS "TS_1",
                               "ERRORLOGANDSERVICELOG_VIEW"."LOG_ETRY"    AS "LOG_ETRY"
                        FROM   "IDS_CORE"."ERRORLOGANDSERVICELOG_VIEW" "ERRORLOGANDSERVICELOG_VIEW") "Extent1") "Extent1"
        WHERE ("Extent1"."row_number" > 1933849)
        ORDER BY "Extent1"."ERR_LOG_ID" ASC)
WHERE (ROWNUM <= (10))
| Id | Operation              | Name                   | Rows | Bytes |TempSpc| Cost (%CPU)| Time     |
|   0 | SELECT STATEMENT       |                        |    10 | 31750 |       |   821K (1)| 02:44:15 |
|* 1 | COUNT STOPKEY         |                        |       |       |       |            |          |
|   2 |   VIEW                 |                        | 1561K| 4728M|       |   821K (1)| 02:44:15 |
|* 3 |    VIEW                |                        | 1561K| 4748M|       |   821K (1)| 02:44:15 |
|   4 |     WINDOW SORT        |                        | 1561K| 3154M| 4066M|   821K (1)| 02:44:15 |
|* 5 |      HASH JOIN OUTER   |                        | 1561K| 3154M|       |   130K (1)| 00:26:09 |
|   6 |       TABLE ACCESS FULL| IDS_SERVICES_LOG       | 1047 | 52350 |       |     5   (0)| 00:00:01 |
|   7 |       TABLE ACCESS FULL| IDS_SERVICES_ERROR_LOG | 1561K| 3080M|       |   130K (1)| 00:26:08 |
Predicate Information (identified by operation id):
   1 - filter(ROWNUM<=10)
   3 - filter("Extent1"."row_number">1933849)
   5 - access("T1"."SRV_LOG_ID"(+)="T2"."SRV_LOG_ID")

I did try a sample from stack overflow that would apply it to all string types, but I didn't see any query results differences. Please note, I am having the problem without any order with or where statements. Of course the skip take generates them. Please advise how I would implement the EntityFunctions.AsNonUnicode method with this Linq query.
LINQ
var cnt = (from errorLog in ctx.ERRORLOGANDSERVICELOG_VIEW
                    select errorLog).Count();
                var query = (from errorLog in ctx.ERRORLOGANDSERVICELOG_VIEW
                             orderby errorLog.ERR_LOG_ID
                             select errorLog).Skip(cnt-10).Take(10).ToList();
This is what I inserted into my model to hopefully fix it. FROM:c# - EF Code First - Globally set varchar mapping over nvarchar - Stack Overflow
/// <summary>
/// Change the "default" of all string properties for a given entity to varchar instead of nvarchar.
/// </summary>
/// <param name="modelBuilder"></param>
/// <param name="entityType"></param>
protected void SetAllStringPropertiesAsNonUnicode(
   DbModelBuilder modelBuilder,
   Type entityType)
   var stringProperties = entityType.GetProperties().Where(
c => c.PropertyType == typeof(string)
   && c.PropertyType.IsPublic
   && c.

Trunc causing Full Table Scans

I have a situtaion here where my query is as follows.
SQL> select count(1) from HBSM_SM_ACCOUNT_INFO where OPTIONAL_PARM5='MH' and CUST_STATUS in ('UP','UUP') and trunc(FIRST_ACTVN_DATE) = trunc(sysdate);
COUNT(1)
6
PLAN_TABLE_OUTPUT
Plan hash value: 3951750498
| Id | Operation | Name | Rows | Bytes | Cost (%CPU)| Time | Pstart| Pstop |
| 0 | SELECT STATEMENT | | 1 | 10 | 13904 (1)| 00:02:47 | | |
| 1 | SORT AGGREGATE | | 1 | 10 | | | | |
| 2 | PARTITION LIST SINGLE| | 1 | 10 | 13904 (1)| 00:02:47 | 12 | 12 |
|* 3 | TABLE ACCESS FULL | HBSM_SM_ACCOUNT_INFO | 1 | 10 | 13904 (1)| 00:02:47 | 12 | 12 |
Predicate Information (identified by operation id):
3 - filter(("CUST_STATUS"='UP' OR "CUST_STATUS"='UUP') AND
TO_DATE(INTERNAL_FUNCTION("FIRST_ACTVN_DATE"))=TO_DATE(TO_CHAR(SYSDATE@!)))
16 rows selected.
If I remove the trunc clause from the query the performance definitely improves the the results are wrong.
SQL> select count(1) from HBSM_SM_ACCOUNT_INFO where OPTIONAL_PARM5='MH' and CUST_STATUS in ('UP','UUP') and FIRST_ACTVN_DATE = trunc(sysdate);
COUNT(1)
0
PLAN_TABLE_OUTPUT
Plan hash value: 454529511
| Id | Operation | Name | Rows | Bytes | Cost (%CPU)| Time | Pstart| Pstop |
| 0 | SELECT STATEMENT | | 1 | 40 | 47 (0)| 00:00:01 | | |
|* 1 | TABLE ACCESS BY GLOBAL INDEX ROWID| HBSM_SM_ACCOUNT_INFO | 1 | 40 | 47 (0)| 00:00:01 | 12 | 12 |
|* 2 | INDEX RANGE SCAN | IND_FIRST_ACTVN_DATE | 51 | | 4 (0)| 00:00:01 | | |
Can someone please help me whereby I can get the right data and I can also prevent these full table scans.

Unless you are using a functional index, applying any function to an indexed column prevents the use of the index.
The way round it in your case is to realise that
select count(1) from HBSM_SM_ACCOUNT_INFO where OPTIONAL_PARM5='MH' and CUST_STATUS in ('UP','UUP') and trunc(FIRST_ACTVN_DATE) = trunc(sysdate)Is really asking that FIRST_ACTVN_DATE should be sometime today. You could therefore rewrite it as
select count(1) from HBSM_SM_ACCOUNT_INFO where OPTIONAL_PARM5='MH' and CUST_STATUS in ('UP','UUP')
and FIRST_ACTVN_DATE >= trunc(sysdate)
and FIRST_ACTVN_DATE < trunc(sysdate) + 1Note, this still might not use the index depending on how many rows are within today's date versus how many are outside today's date.
Also, when posting, remember to put your code between tags and to post create table scripts and sample data inserts.

VARRAY bind parameter in IN clause causes Full Table Scan

Hi
My problem is that Oracle elects to perform a full table scan when I want it to use an index.
The situation is this: I have a single table SQL query with an IN clause such as:
SELECT EMPNO, ENAME, JOB FROM EMP WHERE ENAME IN (...)
Since this is running in an application, I want to allow the user to provide a list of ENAMES to search. Because IN clauses don't accept bind parameters I've been using the Tom Kyte workaround which relies on setting a bind variable to an array-valued scalar, and then casting this array to be a table of records that the database can handle in an IN clause:
SELECT *
FROM EMP
WHERE ENAME IN (
SELECT *
FROM TABLE(CAST( ? AS TABLE_OF_VARCHAR)))
This resulted in very slow performance due to a full table scan. To test, I ran the SQL in SQL*Plus and provided the IN clause values in the query itself. The explain plan showed it using my index...ok good. But once I changed the IN clause to the 'select * from table...' syntax Oracle went into Full Scan mode. I added an index hint but it didn't change the plan. Has anyone had success using this technique without a full scan?
Thanks
John
p.s.
Please let me know if you think this should be posted on a different forum. Even though my context is a Java app developed with JDev this seemed like a SQL question.

Justin and 3360 - that was great advice and certainly nothing I would have come up with. However, as posted, the performance still wasn't good...but it gave me a term to Google on. I found this Ask Tom page http://asktom.oracle.com/pls/ask/f?p=4950:8:::::F4950_P8_DISPLAYID:3779680732446#15740265481549, where he included a seemingly magical 'where rownum >=0' which, when applied with your suggestions, turned my query from minutes into seconds.
My plans are as follows:
1 - Query with standard IN clause
SQL> explain plan for
2 select accession_number, protein_name, sequence_id from protein_dim
3 where accession_number in ('33460', '33458', '33451');
Explained.
SQL> select * from table(dbms_xplan.display);
PLAN_TABLE_OUTPUT
| Id | Operation | Name | Rows | Bytes | Cost |
| 0 | SELECT STATEMENT | | 7 | 336 | 4 |
| 1 | INLIST ITERATOR | | | | |
| 2 | TABLE ACCESS BY INDEX ROWID| PROTEIN_DIM | 7 | 336 | 4 |
| 3 | INDEX RANGE SCAN | IDX_PROTEIN_ACCNUM | 7 | | 3 |
Note: cpu costing is off, 'PLAN_TABLE' is old version
11 rows selected.
2 - Standard IN Clause with Index hint
SQL> explain plan for
2 select /*+ INDEX(protein_dim IDX_PROTEIN_ACCNUM) */
3 accession_number, protein_name, sequence_id, taxon_id, organism_name, data_source
4 from pdssuser.protein_dim
5 where accession_number in
6 ('33460', '33458', '33451');
Explained.
SQL> select * from table(dbms_xplan.display);
PLAN_TABLE_OUTPUT
| Id | Operation | Name | Rows | Bytes | Cost |
| 0 | SELECT STATEMENT | | 7 | 588 | 4 |
| 1 | INLIST ITERATOR | | | | |
| 2 | TABLE ACCESS BY INDEX ROWID| PROTEIN_DIM | 7 | 588 | 4 |
| 3 | INDEX RANGE SCAN | IDX_PROTEIN_ACCNUM | 7 | | 3 |
Note: cpu costing is off, 'PLAN_TABLE' is old version
11 rows selected.
3 - Using custom TABLE_OF_VARCHAR type
CREATE TYPE TABLE_OF_VARCHAR AS
TABLE OF VARCHAR2(50);
SQL> explain plan for
2 select
3 accession_number, protein_name, sequence_id, taxon_id, organism_name, data_source
4 from pdssuser.protein_dim
5 where accession_number in
6 (select * from table(cast(TABLE_OF_VARCHAR('33460', '33458', '33451') as TABLE_OF_VARCHAR)) t);
Explained.
SQL> select * from table(dbms_xplan.display);
PLAN_TABLE_OUTPUT
| Id | Operation | Name | Rows | Bytes | Cost |
| 0 | SELECT STATEMENT | | 2 | 168 | 57M|
| 1 | NESTED LOOPS SEMI | | 2 | 168 | 57M|
| 2 | TABLE ACCESS FULL | PROTEIN_DIM | 5235K| 419M| 13729 |
| 3 | COLLECTION ITERATOR CONSTRUCTOR FETCH| | | | |
Note: cpu costing is off, 'PLAN_TABLE' is old version
11 rows selected.
4 - Using custom TABLE_OF_VARCHAR type w/ Index hint
SQL> explain plan for
2 select /*+ INDEX(protein_dim IDX_PROTEIN_ACCNUM) */
3 accession_number, protein_name, sequence_id, taxon_id, organism_name, data_source
4 from pdssuser.protein_dim
5 where accession_number in
6 (select * from table(cast(TABLE_OF_VARCHAR('33460', '33458', '33451') as TABLE_OF_VARCHAR)) t);
Explained.
SQL> select * from table(dbms_xplan.display);
PLAN_TABLE_OUTPUT
| Id | Operation | Name | Rows | Bytes | Cost |
| 0 | SELECT STATEMENT | | 2 | 168 | 57M|
| 1 | NESTED LOOPS SEMI | | 2 | 168 | 57M|
| 2 | TABLE ACCESS BY INDEX ROWID | PROTEIN_DIM | 5235K| 419M| 252K|
| 3 | INDEX FULL SCAN | IDX_PROTEIN_ACCNUM | 5235K| | 17255 |
| 4 | COLLECTION ITERATOR CONSTRUCTOR FETCH| | | | |
PLAN_TABLE_OUTPUT
Note: cpu costing is off, 'PLAN_TABLE' is old version
12 rows selected.
5 - Using custom TABLE_OF_VARCHAR type w/ cardinality hint
SQL> explain plan for
2 select
3 accession_number, protein_name, sequence_id, taxon_id, organism_name, data_source from protein_dim
4 where accession_number in (select /*+ cardinality( t 10 ) */
5 * from TABLE(CAST (TABLE_OF_VARCHAR('33460', '33458', '33451') AS TABLE_OF_VARCHAR)) t);
Explained.
SQL> select * from table(dbms_xplan.display);
PLAN_TABLE_OUTPUT
| Id | Operation | Name | Rows | Bytes | Cost |
| 0 | SELECT STATEMENT | | 2 | 168 | 57M|
| 1 | NESTED LOOPS SEMI | | 2 | 168 | 57M|
| 2 | TABLE ACCESS FULL | PROTEIN_DIM | 5235K| 419M| 13729 |
| 3 | COLLECTION ITERATOR CONSTRUCTOR FETCH| | | | |
Note: cpu costing is off, 'PLAN_TABLE' is old version
11 rows selected.
6 - Using custom TABLE_OF_VARCHAR type w/ cardinality hint
and rownum >= 0 constraint
SQL> explain plan for
2 select
3 accession_number, protein_name, sequence_id, taxon_id, organism_name, data_source from protein_dim
4 where accession_number in (select /*+ cardinality( t 10 ) */
5 * from TABLE(CAST (TABLE_OF_VARCHAR('33460', '33458', '33451') AS TABLE_OF_VARCHAR)) t
6 where rownum >= 0);
Explained.
SQL> select * from table(dbms_xplan.display);
PLAN_TABLE_OUTPUT
| Id | Operation | Name | Rows | Bytes | Cost |
| 0 | SELECT STATEMENT | | 25 | 2775 | 43 |
| 1 | TABLE ACCESS BY INDEX ROWID | PROTEIN_DIM | 2 | 168 | 3 |
| 2 | NESTED LOOPS | | 25 | 2775 | 43 |
| 3 | VIEW | VW_NSO_1 | 10 | 270 | 11 |
| 4 | SORT UNIQUE | | 10 | | |
| 5 | COUNT | | | | |
| 6 | FILTER | | | | |
PLAN_TABLE_OUTPUT
| 7 | COLLECTION ITERATOR CONSTRUCTOR FETCH| | | | |
| 8 | INDEX RANGE SCAN | IDX_PROTEIN_ACCNUM | 2 | | 2 |
Note: cpu costing is off, 'PLAN_TABLE' is old version
16 rows selected.
I don't understand why performance improved so dramatically but happy that it did.
Thanks a ton!
John

Where columnname like '%somevalue' causing full table scan

hi,
10.2.0.4 database
is it possible to force an index scan over a full table scan if I use a where clause similar to the following:
where col1 like '%somevalue';
There is an index with col1 as the first segment of the index and another column as the second segment of the index.
Thanks
JOhn

I have done it for you
SQL> create index empX on emp(job) ;
Index created.
SQL> explain plan for select * from emp where job like '%ERK' ;
Explained.
SQL> select * from table(dbms_xplan.display) ;
PLAN_TABLE_OUTPUT
Plan hash value: 3956160932
| Id | Operation         | Name | Rows | Bytes | Cost (%CPU)| Time     |
|   0 | SELECT STATEMENT |      |     1 |    37 |     3   (0)| 00:00:01 |
|* 1 | TABLE ACCESS FULL| EMP |     1 |    37 |     3   (0)| 00:00:01 |
Predicate Information (identified by operation id):
   1 - filter("JOB" LIKE '%ERK')
13 rows selected.
SQL> explain plan for select * from emp where job like 'C%ERK' ;
Explained.
SQL> select * from table(dbms_xplan.display) ;
PLAN_TABLE_OUTPUT
Plan hash value: 140376749
| Id | Operation                   | Name | Rows | Bytes | Cost (%CPU)| Time     |
|   0 | SELECT STATEMENT            |      |     4 |   148 |     2   (0)| 00:00:01 |
|   1 | TABLE ACCESS BY INDEX ROWID| EMP |     4 |   148 |     2   (0)| 00:00:01 |
|* 2 |   INDEX RANGE SCAN          | EMPX |     4 |       |     1   (0)| 00:00:01 |
Predicate Information (identified by operation id):
   2 - access("JOB" LIKE 'C%ERK')
       filter("JOB" LIKE 'C%ERK')
15 rows selected.
SQL> explain plan for select /*+index (emp,EMPX) */ * from emp where job like '%ERK' ;
Explained.
SQL> select * from table(dbms_xplan.display) ;
PLAN_TABLE_OUTPUT
Plan hash value: 3745534319
| Id | Operation                   | Name | Rows | Bytes | Cost (%CPU)| Time     |
|   0 | SELECT STATEMENT            |      |     1 |    37 |     2   (0)| 00:00:01 |
|   1 | TABLE ACCESS BY INDEX ROWID| EMP |     1 |    37 |     2   (0)| 00:00:01 |
|* 2 |   INDEX FULL SCAN           | EMPX |     1 |       |     1   (0)| 00:00:01 |
Predicate Information (identified by operation id):
   2 - filter("JOB" LIKE '%ERK')
14 rows selected.SS

Query doing full table scan

Hai all,
10.2.0.4 on solaris 10
SELECT sum(RechargeForPrepaid/10000), to_date(substr (TIMESTAMP, 1,8),'YYYY/MM/DD')
FROM medt.crm_t WHERE to_date(substr (TIMESTAMP, 1,8),'YYYY/MM/DD') >= trunc(sysdate)-1 and tradetype != '0' group by to_date(substr (TIMESTAMP, 1,8),'YYYY/MM/DD');The explain shows that it performs a full table scan on crm_t . I created indexes on the column
timestamp and tradetype too . collected stats too. but still it is doing a full table scan.
Please guide
Thanks
Kai

sybrand_b wrote:
The column is wrongly named --> timestamp is a reserved word.True:
SQL> select * from v$reserved_words where keyword = 'TIMESTAMP'
2 /
KEYWORD                                                              LENGTH
TIMESTAMP                                                                 9
1 row selected.
It is also of the wrong type--> dates shouldn't be stored as varchar2.All we know, is that the column is treated as if it is a VARCHAR2. It doesn't have to be a varchar2, because he might be relying on some implicit datatype conversion.
The design of this table is a complete mess.
Drop it and redesign.You'd better tell that to Oracle as well then :-) :
SQL> desc user_objects
Name                                                                      Null?    Type
OBJECT_NAME                                                                        VARCHAR2(128)
SUBOBJECT_NAME                                                                     VARCHAR2(30)
OBJECT_ID                                                                          NUMBER
DATA_OBJECT_ID                                                                     NUMBER
OBJECT_TYPE                                                                        VARCHAR2(18)
CREATED                                                                            DATE
LAST_DDL_TIME                                                                      DATE
TIMESTAMP                                                                          VARCHAR2(19)
STATUS                                                                             VARCHAR2(7)
TEMPORARY                                                                          VARCHAR2(1)
GENERATED                                                                          VARCHAR2(1)
SECONDARY                                                                          VARCHAR2(1)My point is that the TIMESTAMP datatype was introduced in version 9, and versions prior to that were free to use the name "TIMESTAMP". And all those older applications still function. A redesign would be ideal, but maybe not economically feasible. Oracle certainly didn't choose a redesign.
If you are going to build a new application, then I agree that you'd better not use that reserved word anymore.
Regards,
Rob.

Find out the SQLs which are using a full table scan

Hello all , how can i to find out the queries which are using a full table scan ? Any idea ?

In general, though, why would you want to tune SQL statements that aren't causing problems? Statspack will tell you what the most resource-intensive SQL statements on your system are. A SQL*Net trace of sessions that are performing poorly will indicate which statements are the most resource-intensive for that session. If a statement is incorrectly doing a full-table scan, but it is not causing a problem, why spend time tuning it? If you're not focusing your tuning attention on identifying statements that are causing problems, you'll also miss out on 90% of tuning opportunities which involve rewriting (or eliminating) code to make it more efficient. I can simulate a join on two tables with nested cursor loops, which won't generate a single full table scan, but replacing that code with a real join, while it will cause at least one full table scan, will be orders of magnitude faster.
As an aside, full table scans aren't necessarily a bad thing. If a statement needs to retrieve more than a couple percent of the rows of a table, full table scans are the most efficient way to go.
Justin
Distributed Database Consulting, Inc.
http://www.ddbcinc.com/askDDBC

Slow query due to large table and full table scan

Hi,
We have a large Oracle database, v 10g. Two of the tables in the database have over one million rows.
We have a few queries which take a lot of time to execute. Not always though, it that seems when load is high the queries tend
to take much longer. Average time may be 1 or 2 seconds, but maxtime can be up to 2 minutes.
We have now used Oracle Grid to help us examine the queries. We have found that some of the queries require two or three full table scans.
Two of the full table scans are of the two large tables mentioned above.
This is an example query:
SELECT table1.column, table2.column, table3.column
FROM table1
JOIN table2 on table1.table2Id = table2.id
LEFT JOIN table3 on table2.table3id = table3.id
WHERE table1.id IN(
SELECT id
FROM (
(SELECT a.*, rownum rnum FROM(
SELECT table1.id
FROM table1,
table2,
table3
WHERE
table1.table2id = table2.id
AND
table2.table3id IS NULL OR table2.table3id = :table3IdParameter
) a
WHERE rownum <= :end))
WHERE rnum >= :start
Table1 and table2 are the large tables in this example. This query starts two full table scans on those tables.
Can we avoid this? We have, what we think are, the correct indexes.
/best regards, Håkan

>
Hi Håkan - welcome to the forum.
We have a large Oracle database, v 10g. Two of the tables in the database have over one million rows.
We have a few queries which take a lot of time to execute. Not always though, it that seems when load is high the queries tend
to take much longer. Average time may be 1 or 2 seconds, but maxtime can be up to 2 minutes.
We have now used Oracle Grid to help us examine the queries. We have found that some of the queries require two or three full table scans.
Two of the full table scans are of the two large tables mentioned above.
This is an example query:Firstly, please read the forum FAQ - top right of page.
Please format your SQL using tags [code /code].
In order to help us to help you.
Please post table structures - relevant (i.e. joined, FK, PK fields only) in the form - note use of code tags - we can just run table create script.
CREATE TABLE table1
Field1 Type1,
Field2 Type2,
FieldN TypeN
);Then give us some table data - not 100's of records - just enough in the form
INSERT INTO Table1 VALUES(Field1, Field2.... FieldN);
..Please post EXPLAIN PLAN - again with tags.
HTH,
Paul...
/best regards, Håkan

Update Query is Performing Full table Scan of 1 Millions Records

Hello Everyboby I have one update query ,
UPDATE tablea SET
          task_status = 12
          WHERE tablea.link_id >0
          AND tablea.task_status <> 0
          AND tablea.event_class='eventexception'
          AND Exists(SELECT 1 from tablea ltask where ltask.task_id=tablea.link_id
          AND ltask.task_status = 0)
When I do explain plan it shows following result...
Execution Plan
0 UPDATE STATEMENT Optimizer=CHOOSE
1 0 UPDATE OF 'tablea'
2 1 FILTER
3 2 TABLE ACCESS (FULL) OF 'tablea'
4 2 TABLE ACCESS (BY INDEX ROWID) OF 'tablea'
5 4 INDEX (UNIQUE SCAN) OF 'PK_tablea' (UNIQUE)
NOW tablea may have more than 10 MILLION Records....This would take hell of time even if it has to
update 2 records....please suggest me some optimal solutions.....
Regards
Mahesh

I see your point but my question or logic say i have index on all columns used in where clauses so i find no reason for oracle to do full table scan,,,,
UPDATE tablea SET
task_status = 12
WHERE tablea.link_id >0
AND tablea.task_status <> 0
AND tablea.event_class='eventexception'
AND Exists(SELECT 1 from tablea ltask where ltask.task_id=tablea.link_id
AND ltask.task_status = 0)
I am clearly statis where task_status <> 0 and event_class= something and tablea.link_id >0
so ideal case FOR optimizer should be
Step 1)Select all the rowid having this condition...
Step 2)
For each row in rowid get all the row where task_status=0
and where taskid=linkid of rowid selected above...
Step 3)While looping for each rowid if it find any condition try for rowid obtained from ltask in task 2 update that record....
I want to have this kind of plan,,,,,does anyone know how to make oracle obtained this kind of plan......
It is try FULL TABLE SCAN is harmfull alteast not better than index scan.....

SIDs for Full table scan wait events in db

Guys,
10.2.0.5/ 2 node RAC / RHEL-3
CanAnyone provide me an sql to find all SID doing full table scans in a db?
Thanks!
Hari

You ought to be able to query v$sql_plan for those sql plans with a full scan in them and if you want all the recent plans that contain a full table scan in them. You can join this back to v$session for those session currently executing a full table scan but if the sql in question was a previous statement executed by the session the join will not show the session because that statement is no longer the current statement.
1 select p.sql_id, s.sid, p.object_name, p.operation, p.options
2 from v$sql_plan p, v$session s
3 where p.options like '%FULL%'
4* and s.sql_id = p.sql_id
You will probably want to filter out internal operations (operation = "FIXED TABLE")
HTH -- Mark D Powell --

Finding the Text of SQL Query causing Full Table Scans

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