SQL & PL/SQL :: Performance Of Varchar2 Fields Based On Width?
Nov 10, 2010
I did a search on this topic and did see the ASK TOM response that storing all varchar2 fields as (2000) or what not is a bad idea based on an array fetch that developers may use etc. However I'm not sure that applies to my specific question, and the other examples he gave certainly didn't apply. So I'll pose the question a different way:
Question #1: Is there, for example, a performance difference between setting a field as varchar(2000) and varchar(25) if I was just running a native SQL query using a front end tool like TOAD?
Question #2: If I also need to index that field, will it take longer to index a varchar(2000) field than a varchar(25) field, assuming the same data is in both fields?
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Sep 30, 2010
How the length of column width effects index performance?
For example if i had IOT table emp_iot with columns:
(id number,
job varchar2(20),
time date,
plan number)
Table key consist of(id, job, time)
Column JOB has fixed list of distinct values ('ANALYST', 'NIGHT_WORKED', etc...).
What performance increase i could expect if in column "job" i would store not names but concrete numbers identifying job names.
For e.g. i would store "1" instead 'ANALYST' and "2" instead 'NIGHT_WORKED'.
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Jul 21, 2011
Once a year in the application we have a specific query that gets used a lot. It's an UPDATE that updates a single record in a single table with a few different datatypes, but the issue is happening with one of the VARCHAR2 fields. It updates one VARCHAR2(2000) and three VARCHAR2(4000) fields at the same time.
This year, 9 of the 95 times it was used resulted in one of the VARCHAR2(4000) fields as null in the database. The users would not want this field to be null and 5 of the 9 have told us they entered something (the form they're filling out is a research proposal and leaving this field empty would be pointless because it's part of the funding request, so they're not doing it). The application isn't doing it because it's not consistent. I've checked the application and these fields can't be nulled any other way.
We just found the issue so I looked back over the past years back to 2005. Last year it didn't happen at all. In 2010 it happened a handful of times. Some years there were even more times. It's not always the same field but it's always a VARCHAR2 of at least 2000 characters.
I have a lot more information but it's all just details (let me know if you need to know more). I'm wondering if there is a bug in 10g with these types of fields. I don't believe it's malicious behavior on an individual's part but I suppose that's always possible.
how to research something like this. I tried to get access to Oracle Support and the Knowledge Base I heard they have but it doesn't look like I can do that
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Oct 20, 2011
Do we have measure with Oracle sequence width compare with column width.?
today i have ticket to check that.
Quote:Comparing sequence width to column width.We need to be Pro-active and continuous effort (not one time) meaning, any ccput by developer (for new sequence or new column which has corresponding sequence) need to be verified from this perspective
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Oct 13, 2011
I need to partition a existing table based on varchar2 field (which is actaully date value but storing as character in the table). Using below statement for creating table, but getting error.
create table TST_CUST_ARC
(
interact_id NUMBER(10),
extrn_id VARCHAR2(38),
src_cd VARCHAR2(25),
full_nm VARCHAR2(45),
run_control_date VARCHAR2(13)
[code]....
Getting error : ORA-00907: missing right parenthesis
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Feb 9, 2011
I need to create a materialized view with a clob column based on a varchar2 column of a table.This is because in the mv the clob column data gets appended one after another.
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Sep 15, 2011
I have the following situation and need support:
create table try_x
(a number PRIMARY KEY,
b NUMBER,
c NUMBER,
f_text VARCHAR2(10));
insert ALL
into try_x values (0,1,1,'abc')
into try_x values (1,1,1,'abc')
into try_x values (2,1,1,'xyz')
into try_x values (3,1,2,'abc')
into try_x values (4,1,2,'abc')
into try_x values (5,1,2,'abc')
into try_x values (6,1,3,'abc')
into try_x values (7,1,3,'abc1')
into try_x values (8,1,3,'abc2')
into try_x values (9,1,3,'abc2')
select * from DUAL;
Although a is the PK, records with similar b,c,f_text are considered redundant and I need to delete all occurrences in the table where b, c, d are redundant and leave the unique ones. So I need the result to look like:
a b c f_text
-----------------
0 1 1 abc
2 1 1 xyz
3 1 2 abc
6 1 3 abc
7 1 3 abc1
8 1 3 abc2
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Jul 20, 2010
With a very large database (VLDB) for a data warehouse (DW) using primarily a STAR based schema in an environment in which time (both human and CPU) is orders of magnitude more valuable than storage capacity, is there any signficant difference in query performance when tables have all fixed length (CHAR) columns compared to tables with variable length (VARCHAR2) columns?
I realize this is one of those "in general" questions so considering "a given VLDB DW environment" with all other things being equal, what, if any, is the time based performance difference between a database of tables with all fixed sized columns versus one of tables with variable length columns ?
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Nov 6, 2012
I have been used to the consciousness that we should use the minimum length for varchar2 field that can store the data we need manipulate. But recently I was told that it has little impact on performance if we assign a much longer size.
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Jul 13, 2011
I am having a problem with auto populating different fields based on inventory no. field.. This is a bug giving to me to work on and i not able to figure out how to populate the other fields.
How to set any triggers for the items to auto populate and i am suppose to finish this work today.
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Feb 14, 2013
I Want to tune the attached query. I have tried by creating the normal indexes and composite indexes on the fields . I feel that , Only normal index is required for this instead of composite index?
11:15:19 SQL> @slot.sql
11:16:03 SQL>
11:16:03 SQL> drop table slot purge;
Table dropped.
Elapsed: 00:00:00.05
11:16:03 SQL>
11:16:03 SQL> create table slot
11:16:03 2 (
11:16:03 3 id varchar2 (40) not null,
[code]....
- dynamic sampling used for this statement
22 rows selected.
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Oct 24, 2007
i am fairly new in the oracle arena, but what would cause a statement such as
ALTER TABLE TEST_TABLE MODIFY text_field1 varchar2(100) DEFAULT 'testval' NULL
to change a column's type from VARCHAR2(100) to VARCHAR2(100 byte)? i found a few mentions of the 100 byte concept online but nothing that jumped out at me.
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Feb 22, 2012
I have a table which has 4M records
This table has a query where one of the condition is
AND STATUS <> 'C'
Now the data is as following
select count(*) record_count, status from new_business group by status;
record_countstatus
4298025C
15N
13Q
122S
I want to know if following index would be useful in this case while the condition in where clause is
"AND STATUS <> 'C'"
create index nb_index_1 on new_business(case when status in('N','Q','S') then 1 else NULL end);
Or
create index nb_index_1 on new_business(case when status ='N' then 'N' when status='Q' then 'Q' when status='S' then 'S' else NULL end);
I tried it on a sample table but the index is simply not picked up even when hinted following are the db level settings
query_rewrite_enabled string TRUE
query_rewrite_integrity string enforced
I tried it 'query_rewrite_integrity' with 'trusted' as well .
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May 17, 2012
Would using a blob based schema load noticeably faster than a binary_double based schema?
CODEBlob Scenario:
Load 1 row: 5 columns (1 integer column, 4 blob columns) of size X
VERSUS
CODEDouble Scenario:
Load 10,000 rows: 5 columns (1 integer column, 4 binary_double columns) of size X
While the benefit of using the rows approach is obviously the capability to query the values, I'd like quick answer concerning the loading/insertion performance. Associative array binding is used for loading from a .NET client. Also, would the answer also hold true for 200 columns instead of just 5 columns.
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Dec 11, 2006
I'm having a problem with a column that is too short for it's data. It causes multiple lines for the same record. How can I change a column width in Oracle? I'm using a select statement to see the data.
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Sep 20, 2004
I am using SQL Plus v9.2.0.1.0 and am having trouble with the column widths. By way of example:
Let's say the column is a varchar(2) and the column name is called V9ABC12345. When I see the result of my query I only get the heading name as V9 ie the maximum width of 2 characters. The table has over 100 columns and I know I can specify the column width using the format command but I am using the select * from table_name command
How do I change my formatting to include the column heading by default?
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Feb 10, 2010
i edit forms
web.cfg
width=100%
height=100%
so all applet is loaded full screen in browser.But i want to load particular form with different width and height
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Oct 10, 2013
11gxe , apex 4.0 , firefox 24 ,i want to decrease width of a specific region , how ?
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Jun 25, 2013
i have a problem in my ODI 11g with the load into Oralce table of a fixed width file, i configured all the datasource in ODI and when i do view data i see all correct, the end of file is signed like "0D0A" but when i try my load interface i receive the message that my last field is more big than the one declared.
My file have an header of fields and the last field is a data-field of 2000 characters. I controlled and is really fixed the length cause is a COBOL file from a Mainframe. So it looks that ODI don't understand the end of that field and go ahead to the other, i just tryed to enlarge the limit but is always more big like if the file is shifting on the right.
Have i forgot some configuration in some place? The definition of the file present the end of file like Microsoft hexadecimal \u000D\u000A i try all the combination there but no way to avoid this problem.
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Jul 16, 2013
I have a column named 'Comment'. Its have a huge data due to which the length of that column in interactive report get increased.
I need to fix the length to a desired value.I used following code in Region Footer:
<style> table.apexir_WORKSHEET_DATA td[headers=COMMENTS] { _width: 300px; min-width: 50px; max-width: 300px }</style>
Its solved the problem by fixing the width of the column but the column is not showing the full data now. It is hiding most of its part to fit it in that column.
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Jul 10, 2012
How to control the column width on an interactive report. I can force it by making the column header really long but that is a crazy solution. How can I get control over this? I have columns that contain memo entries and if I use the header memo the report has tall skinny columns which makes reading very difficult.
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Nov 13, 2013
Apex 4.2I have a page with a calendar on it. I have several issues with formatting the data within each cell. Currently, I use a substitution string to place the id in the calendar cell.
Clicking the id will link to another page. What I notice is that for each id on a calendar cell (or date), it lists them one under the other. Is there any way to list them side by side? Also, I need to make changes to the calendar cells. I would like to expand the width and the height, but am not sure where to do this.
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Apr 14, 2013
I understand when I decrease the width or height of the paper layout, it may cause this error if any of the objects in my report may not fit in the new layout.
But for me this error occurs even when I increase the size of my report paper layout!
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Feb 21, 2011
I have a column named "col1" with datatype "varchar2(10)" and row wise entries like "1,1A, 2,3...,10,2A,..." like. I want to order it like "1, 1A ,2,2A, 2B,3... 10...".I tried it with to_number() but it gives me
1,10,11,2,....like that.
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Jun 13, 2012
What is the best alternative to using VARCHAR2 if the output gets truncated after 4000 bytes in a PL/SQL function?
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Mar 23, 2010
in our application we are using clob column instead of varchar2 because varchar2 does not allow more that 4000 chars, so Using clob allows to put data of any length, will it cause performance issues ? we have this column in almost in all tables .
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Sep 28, 2010
create table members(
memberID varchar2(7),
locationID number(5),
roomID varchar2(5)
)
/
[Code]....
MEMBERI LOCATIONID ROOMI
------- ---------- -----
2007209 1 1
2006253 1 1-A
2006253 1 1-A
2006265 1 1-B
2006240 1 1-C
2005064 1 1-D
2007836 1 100
2007211 1 101
2007075 1 102
2007110 1 105
[Code]...
Function created.
SQL> select * from members
2 order by safe_to_number(roomID);
MEMBERI LOCATIONID ROOMI
------- ---------- -----
2007209 1 1
2007185 1 2
2007089 1 3
2007023 1 4
[Code]....
How can I sort the output to get the result like below
2007209 1 1
2006253 1 1-A
2006253 1 1-A
[Code]...
and so on...
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May 14, 2011
I have 2 tables.The column in table A is number and Column in table B is a varchar2 datatype.I have to use the Column of table B as a filter to column of Table A.Below is the example.
create table A(Col1 number);
Inert into A values(1);
Inert into A values(2);
Inert into A values(3);
Inert into A values(4);
Create table B(Col1 Varchar2(100));
Insert into b value ('1,2,3');
Select * from A where col1 in (select col1 from b)
Error: Invalid Number
Is there a way to convert the varchar to number.The varchar field have multiple characters (numbers) seperated by commas.
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Mar 28, 2008
How to convert a varchar2 column to CLOB when there is a thousands of records in it.
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Jan 15, 2013
How to convert varchar2 to number data?
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