can I create an index on the column of duplicate lines?
HelloI tried to create a unique index on an existing table, containing the duplicate lines.
I want to create an index of type everything on this column of duplicate rows.
If possible pls suggest me.
Kind regards
Vincent.
Yes.
Tags: Database
Similar Questions
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index on the column of low cardinality
Hello
Standard edition Oracle 10.2
I have a 'status' column in my table. table contains about 100000 records.
The possible values of status will be 1 or 2 (digital). This column will be 5 to 10 percent of the population, and the rest is null.
Because it is seems that bitmap index is candidate for low cardinality column, but this picture has high of DML operations. SO by web research I learned about this bitmap causes problems of blocking on high DML operations.
So I think that B-tree is only option left. Can you suggest a good index to improve performance on such a column?You don't need an index based on a function, do you think?
You have a STATUS column where a small percentage of values is not null.
To effectively access these lines whose STATUS is non-zero, simply create an index on the column State.
This should be plenty effective.
The effectiveness of this index (or the fbi if she was forced) is based on the fact that an index b-tree contains entry when the value is null (or all of the values in the case of a composite).
There are those that 100000 is small and 5-10% is not particularly selective and you tell the width of the table, etc., so, even with the index here, it might not if used - i.e. depending on the circumstances it might be more efficient to do a FTS.
It depends on what you want to do.
See:
http://asktom.Oracle.com/pls/asktom/f?p=100:11:0:P11_QUESTION_ID:4433887271030
http://richardfoote.WordPress.com/2008/05/12/index-scan-or-full-table-scan-the-magic-number-magic-dance/Published by: Dom Brooks on February 10, 2011 12:58
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can we create an index only for a given value in a column?
Thank youdesc TAB_A ----------------- id1 Number Primary key, id2 Number, col1 varchar2(10), col2 varchar2(10) select count(*) from TAB_A -------------------- 4587609 select count(*) from TAB_A where id2=10 ------------------ 6000 Here is my question can i create an index only for the cloumn id2 only for the value 10?
MikeHi, Mike,.
You can have a function-based index.
CREATE INDEX tab_a_id2_10 ON tab_a ( CASE WHEN id2 IN (10) THEN id2 END );
In Oracle 11.2, it might be cleaner to have a virtual column (indexed).
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How can I create a constraint on the combination of four columns...
Dear Guru,
I have a question... I created the table with columns like "CCode', 'Size1', 'Size2', 'Sch1', 'Sch2', 'Description', 'CCdate '.
Here I wanted to create a unique constraint on the combination of four columns "CCode', 'Size1', 'Size2', 'Sch1', 'Sch2.
My requirement is that I don't want to allow duplicate records in the table for the four columns only.
for example: "CC123", 10, 25, S110, S250,.
If the new record comes with the same data. Then, I do not want to insert this record.i want to get a constraint voilated error.
How can I create a constraint on the combination of four columns...
Pls help me on this issue...
Kind regards
Shitab...
I suggested already here the syntax,
ALTER table your_table
Add constraint cons_name unique (col1, col2, col3, col4, col5);
And don't call me 'Sir '.
See you soon!
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index on the column using custom function
Can we create index on the column using custom function?http://www.dbasupport.com/Oracle/ora8/FBI.shtml
Kind regards
Kaila Mahesh -
How to create faster index in the table of 500 GB
Dear Experts,
I have to create 20 index on table data-ware house. This table is of size 500 GB.
freshen up this weekly chart using the external table.
creating 20 indexes on this table consumes a lot of time.
I have 40 GB of ram on 2012 box windows with 8 processors.
I installed 11 GR 2.
I have 4 drives C D E F
for AN index, it takes 4 hours
I added enough space to the tablespace
I put the tablespace in a drive D:\
I'm under control to create indexes below
create index X_3_INVEN_ITEM_ID_IDX on X_3_PV_TD_2 (INVENTORY_ITEM_ID) parallel 32 nologging;
output long ops
SID, SERIAL # CONTEXT SOFAR TOTALWORK LESS TARGET % _COMPLETE TIME_REMAINING
---------- ---------- ---------- ---------- ---------- ---------------------------------------------------------------- ---------------------------------------------------------------- ---------- --------------
108 10 0 3758 140973 Rowid Scan AD range. X_3_PV_TD_2 2.67 256
173 23 0 5279 141470 Rowid Scan AD range. X_3_PV_TD_2 3.73 258
114 6 0 10092 141786 Rowid Scan AD range. X_3_PV_TD_2 7.12 261
99 59 0 46283 325908 Sort Output 14.2 15207
68 214 0 46763 323623 Sort Output 14.45 14973
35 93 0 47531 318364 Sort Output 14.93 14570
164 70 0 45058 288506 Sort Output 15.62 12886
227 31 0 44130 282285 Sort Output 15.63 13011
13 3 0 51890 309515 Sort Output 16.76 12874
222 67 0 28837 141380 Rowid Scan AD range. X_3_PV_TD_2 20.4 343
73 37 0 32472 141488 Rowid Scan AD range. X_3_PV_TD_2 22.95 212
47 8 0 34332 141154 Rowid Scan AD range. X_3_PV_TD_2 24,32 202
176 20 0 35197 141161 Rowid Scan AD range. X_3_PV_TD_2 24.93 205
19 7 0 35239 141325 Rowid Scan AD range. X_3_PV_TD_2 24.93 205
80 4 0 40399 141611 Rowid Scan AD range. X_3_PV_TD_2 28,53 193
144 20 0 44960 141481 Rowid Scan AD range. X_3_PV_TD_2 31,78 182
233 101 0 74086 169228 Rowid Scan AD range. X_3_PV_TD_2 43,78 176
128 165 0 78765 141436 Rowid Scan AD range. X_3_PV_TD_2 55.69 173
235 1 0 41199796 70035728 table Scan AD. X_3_PV_TD_2 58,83 19804
199 6 0 52748651 70035728 table Scan AD. X_3_PV_TD_2 75,32-9709
44 2 0 53686039 70035728 table Scan AD. X_3_PV_TD_2 76,66 9022
204 26 0 119969 141464 Rowid Scan AD range. X_3_PV_TD_2 84.81 40
202 48 0 138880 162276 Rowid Scan AD range. X_3_PV_TD_2 85.58 43
17 33 0 126506 141778 Rowid Scan AD range. X_3_PV_TD_2 89.23 28
48 7 0 137772 141360 Rowid Scan AD range. X_3_PV_TD_2 97.46 15
Temp tablespace
USED_MB USED TOT_MB % NOM_TABLESPACE
------------------------------ ---------- ---------- ----------
TEMP 11533 286719 4.02temporary tables
OWNER SEGMENT_NAME SEGMENT_TY TABLESPACE_NAME EXTENTS BYTES_
---------- ------------------------------ ---------- -------------------- ---------- ---------------
AD 156.1601650 TEMPORARY USERS 96 209,715,200Question:
How to fix this?
(a) run several parallel create sqlplus statement index different sessions
(b) create a tablespace to put data files in different hard drives like D: E: F: C:
(c) create the separate tablespace for each hard drive and map it to a single disk IO benefit
(d) I have 8 processors but parallel 32 is not speed
(e) how these clues I can run in parallel. Is it OK to run 20 parallel index 32 sqlplus sessions
All that I have to create 20 index on the table of 500 GB
target memory = 30GB
index of names to create 20, each index is 10 GB
his is of 80 hours (4 hours per index)
This machine is waiting, I just used all the resources of the machine to accelerate.
Thanks for reading this
Thanks for the help in advance
I was talking about your end of issue speed up construction of index, where I proposed
orclz >
orclz > alter session set workarea_size_policy = manual;
Modified session.
orclz > alter session set sort_area_size = 2147483647;
Modified session.
orclz > create index
Post edited by: JohnWatson
Sorry, I misread it: this question was not from you. My apologies. My solution should work for you, however: give yourself a big PGA, manually. Automatic PGA management using not will never give you enough.
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