I have index on column column1 and because of the nvl, the optimizer is not picking up the index
How can I restructure the query to avoid nvl giving same result using index on column1?
now column1 and column2 are varchar2 fields here
where nvl(column1,'*')=(nvl(:param1,nvl(column2,'*'))
can I use case statement like
case when column>'' then .. stuckup here
I have a requirement where the user input values will be passed as comma separated string to backend, which is queried against the table using instr. But the index present on the table is not using the index , due to the instr function.How can I create a index in such a way that The instr function uses it.
CREATE TABLE TEST_IDX
(
CCN VARCHAR2(10 CHAR),
SKU_NUM VARCHAR2(10 CHAR),
MOD VARCHAR2(10 CHAR),
SKU_STATUS VARCHAR2(2 CHAR),
RPT_FLAG VARCHAR2(2 CHAR),
CYCLE_AS_OF_DATE DATE,
SMP_IDENTIFIER NUMBER,
MEASURE_NAME VARCHAR2(100 CHAR)
);
CREATE INDEX TEST_IDX1 ON TEST_IDX
(CCN, SMP_IDENTIFIER, MOD, CYCLE_AS_OF_DATE, RPT_FLAG,
MEASURE_NAME);
The below query is going for full table scan due to this.
select * from test_idx where (INSTR (','||'E10000'||',', ',' || ccn || ',') <> 0 OR 'E10000' = 'DEFAULT')
and mod='90396' and rpt_flag='O' and smp_identifier=2
how to recreate the above index so that these queries uses this index.
somehow cannot understand why index is not used
in Oracle Database 11g Release 11.2.0.3.0 - 64bit Production
1. Included only indexed column and got a perfect plan
explain plan for2 select s.x_cnt
3 from reported_summary s
4 where s.x_cnt>0;
PLAN_TABLE_OUTPUT
--------------------------------------------------------------------------------
Plan hash value: 2674489506
-------------------------------------------------------
| Id | Operation | Name | Cost (%CPU)|
-------------------------------------------------------
| 0 | SELECT STATEMENT | | 306 (8)|
|* 1 | INDEX FAST FULL SCAN| S_NUI01 | 306 (8)|
-------------------------------------------------------
Predicate Information (identified by operation id):
---------------------------------------------------
1 - filter("s"."x_CNT">0)
2. Included some other column and got TABLE ACCESS FULL
explain plan for2 select s.x_cnt,s.ru_id
3 from reported_summary s
4 where s.x_cnt>0;
PLAN_TABLE_OUTPUT
--------------------------------------------------------------------------------
Plan hash value: 2142873335
---------------------------------------------------------------
| Id | Operation | Name | Cost (%CPU)|
---------------------------------------------------------------
| 0 | SELECT STATEMENT | | 2421 (3)|
|* 1 | TABLE ACCESS FULL| REPORTED_SUMMARY | 2421 (3)|
---------------------------------------------------------------
Predicate Information (identified by operation id):
---------------------------------------------------
1 - filter("s"."x_CNT">0)
3. Included all other columns and got TABLE ACCESS FULL as well explain plan for2 select s.x_cnt,s.* 3 from reported_summary s 4 where s.x_cnt>0;
PLAN_TABLE_OUTPUT
--------------------------------------------------------------------------------
Plan hash value: 2142873335
---------------------------------------------------------------
| Id | Operation | Name | Cost (%CPU)|
---------------------------------------------------------------
| 0 | SELECT STATEMENT | | 2421 (3)|
|* 1 | TABLE ACCESS FULL| REPORTED_SUMMARY | 2421 (3)|
---------------------------------------------------------------
Predicate Information (identified by operation id):
---------------------------------------------------
1 - filter("s"."x_CNT">0)
I came across situation where a Nullable column is not using index for 'order by' clause. I added Not Null condition in the 'where' condition but it wasn't useful. I don't wanted to make composite index with not nullable column or with constant or modify column to 'Not Null'
So I carried out test cases and during which I found that in one case the sql statement does 'fast full scan' for data access but does not use index for 'order by' sorting
here are the steps
Initially I kept the column Nullable
SQL> create sequence s5;
Sequence created.
SQL> create table t5 as select s5.nextval id,a.* from dba_objects a where rownum<1001;
Table created.
SQL> set pages 100
SQL> select column_name,nullable from user_tab_columns where table_name='T5';
SQL> create index i5 on t5(id);
Index created.
SQL> exec dbms_stats.gather_table_stats(user,'T5',cascade=>true);
PL/SQL procedure successfully completed.
exit
SQL> alter session set events '10046 trace name context forever, level 12';
select *
from
t5 where id is not null order by id
call count cpu elapsed disk query current rows
------- ------ -------- ---------- ---------- ---------- ---------- ----------
Parse 1 0.00 0.00 0 0 0 0
Execute 1 0.00 0.00 0 0 0 0
Fetch 68 0.00 0.00 0 16 0 1000
------- ------ -------- ---------- ---------- ---------- ---------- ----------
total 70 0.01 0.00 0 16 0 1000
Misses in library cache during parse: 1
Optimizer mode: ALL_ROWS
Parsing user id: 5
Rows Row Source Operation
------- ---------------------------------------------------
1000 SORT ORDER BY (cr=16 pr=0 pw=0 time=4771 us)
1000 TABLE ACCESS FULL T5 (cr=16 pr=0 pw=0 time=1157 us)
Elapsed times include waiting on following events:
Event waited on Times Max. Wait Total Waited
---------------------------------------- Waited ---------- ------------
SQL*Net message to client 68 0.00 0.00
SQL*Net message from client 68 49.49 49.72
********************************************************************************
select /*+ index(t i5) */ *
from
t5 t where id is not null order by id
call count cpu elapsed disk query current rows
------- ------ -------- ---------- ---------- ---------- ---------- ----------
Parse 1 0.00 0.00 0 0 0 0
Execute 1 0.00 0.00 0 0 0 0
Fetch 68 0.00 0.00 0 150 0 1000
------- ------ -------- ---------- ---------- ---------- ---------- ----------
total 70 0.00 0.00 0 150 0 1000
Misses in library cache during parse: 1
Optimizer mode: ALL_ROWS
Parsing user id: 5
Rows Row Source Operation
------- ---------------------------------------------------
1000 TABLE ACCESS BY INDEX ROWID T5 (cr=150 pr=0 pw=0 time=5167 us)
1000 INDEX FULL SCAN I5 (cr=71 pr=0 pw=0 time=3141 us)(object id 4673065)
Elapsed times include waiting on following events:
Event waited on Times Max. Wait Total Waited
---------------------------------------- Waited ---------- ------------
SQL*Net message to client 69 0.00 0.00
SQL*Net message from client 69 22.89 28.04
Now I modified the 'id' column to Not Null
SQL> alter table t5 modify id not null;
SQL> set pages 100
SQL> select column_name,nullable from user_tab_columns where table_name='T5';
COLUMN_NAME N
------------------------------ -
ID N
OWNER Y
OBJECT_NAME Y
SUBOBJECT_NAME Y
OBJECT_ID Y
DATA_OBJECT_ID Y
OBJECT_TYPE Y
CREATED Y
LAST_DDL_TIME Y
TIMESTAMP Y
STATUS Y
TEMPORARY Y
GENERATED Y
SECONDARY Y
14 rows selected.
select *
from
t5 order by id
call count cpu elapsed disk query current rows
------- ------ -------- ---------- ---------- ---------- ---------- ----------
Parse 1 0.00 0.01 0 29 0 0
Execute 1 0.00 0.00 0 0 0 0
Fetch 68 0.00 0.00 0 16 0 1000
------- ------ -------- ---------- ---------- ---------- ---------- ----------
total 70 0.01 0.01 0 45 0 1000
Misses in library cache during parse: 1
Optimizer mode: ALL_ROWS
Parsing user id: 5
Rows Row Source Operation
------- ---------------------------------------------------
1000 SORT ORDER BY (cr=16 pr=0 pw=0 time=2398 us)
1000 TABLE ACCESS FULL T5 (cr=16 pr=0 pw=0 time=1152 us)
Elapsed times include waiting on following events:
Event waited on Times Max. Wait Total Waited
---------------------------------------- Waited ---------- ------------
SQL*Net message to client 68 0.00 0.00
SQL*Net message from client 68 37.74 37.91
********************************************************************************
select /*+ index(t i5) */ *
from
t5 t order by id
call count cpu elapsed disk query current rows
------- ------ -------- ---------- ---------- ---------- ---------- ----------
Parse 1 0.00 0.00 0 0 0 0
Execute 1 0.00 0.00 0 0 0 0
Fetch 68 0.00 0.00 0 150 0 1000
------- ------ -------- ---------- ---------- ---------- ---------- ----------
total 70 0.00 0.00 0 150 0 1000
Misses in library cache during parse: 1
Optimizer mode: ALL_ROWS
Parsing user id: 5
Rows Row Source Operation
------- ---------------------------------------------------
1000 TABLE ACCESS BY INDEX ROWID T5 (cr=150 pr=0 pw=0 time=4166 us)
1000 INDEX FULL SCAN I5 (cr=71 pr=0 pw=0 time=3142 us)(object id 4673065)
Elapsed times include waiting on following events:
Event waited on Times Max. Wait Total Waited
---------------------------------------- Waited ---------- ------------
SQL*Net message to client 68 0.00 0.00
SQL*Net message from client 68 8.28 8.45
select id
from
t5 order by id
call count cpu elapsed disk query current rows
------- ------ -------- ---------- ---------- ---------- ---------- ----------
Parse 1 0.00 0.00 0 0 0 0
Execute 1 0.00 0.00 0 0 0 0
Fetch 68 0.00 0.00 0 6 0 1000
------- ------ -------- ---------- ---------- ---------- ---------- ----------
total 70 0.00 0.00 0 6 0 1000
Misses in library cache during parse: 1
Optimizer mode: ALL_ROWS
Parsing user id: 5
Rows Row Source Operation
------- ---------------------------------------------------
1000 SORT ORDER BY (cr=6 pr=0 pw=0 time=1342 us)
1000 INDEX FAST FULL SCAN I5 (cr=6 pr=0 pw=0 time=1093 us)(object id 4673065)
Elapsed times include waiting on following events:
Event waited on Times Max. Wait Total Waited
---------------------------------------- Waited ---------- ------------
SQL*Net message to client 68 0.00 0.00
SQL*Net message from client 68 1.88 1.89
Questions are
1) Why adding 'where id is not null wasn't enough for the index to get used in 'order by'?
2) While we got 'fast full scan' why index wasn't used for 'order by' clause?
3) Do we need the indexed column in where clause for being used in 'order by clause' too?
4) Do we need 'order by' clause if we are selecting only the indexed column with sequence generated values?
Env: RHEL 5.8 RAC 11.2.0.2
I'm currently moving an IOT from one database to another using expdp/imdp. The IOT is non-partitioned and about 100GB in size containing ~1,1 billion rows.
The dumpfile contains nothing else but the IOT. I'm importing with no special parameters, no pre-created IOT, just ordinary dumpfile import. (impdp username/password dumpfile=impdp:iot.dmp nologfile=y )
During import I got unable to extend TEMP errors from impdp.
ORA-39171: Job is experiencing a resumable wait.
ORA-01652: unable to extend temp segment by 128 in tablespace TEMP
ORA-39171: Job is experiencing a resumable wait.
ORA-01652: unable to extend temp segment by 128 in tablespace TEMP
I had to add 2 additional files to my Temp tablespace (total 96GB of temp) before the import could finish off.
Is this temp usage to be expected when importing IOT's ?
The below query is not performing good.
SELECT * FROM wedb_master
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how improve the performance of IS NOT NULL predicate.
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[code].....
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Oracle Text, 11.2.0.3.0
14:33:05 06/26/12 begin logging
14:33:05 06/26/12 event
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[Code]....
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oracle11g
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........ some code here....
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[code]....
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[code]...
