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Home -> Community -> Mailing Lists -> Oracle-L -> RE: flag
Guang,
DATA_LENGTH in DBA_TAB_COLUMNS does not represent actual space occupied
by the column in particular record.
NUMBER type will use varied length based on the value stored.
Igor Neyman, OCP DBA
ineyman_at_perceptron.com
-----Original Message-----
Sent: Thursday, May 22, 2003 11:12 AM
To: Multiple recipients of list ORACLE-L
SQL> select * from v$version;
BANNER
SQL> create table t1(f1 char(1), f2 varchar2(1), f3 number, f4 number(1));
Table created.
SQL> select COLUMN_NAME,DATA_LENGTH from cols where TABLE_NAME='T1';
COLUMN_NAME DATA_LENGTH ------------------------------ ----------- F1 1 F2 1 F3 22 F4 22
So it looks like no matter what precision one defines for NUMBER column,
the
data_length is always 22. So char or varchar would use less space for
column
data (not index data).
Guang
> -----Original Message-----
> From: root_at_fatcity.com [mailto:root_at_fatcity.com]On Behalf Of
> Orr, Steve
> Sent: Thursday, May 22, 2003 11:07 AM
> To: Multiple recipients of list ORACLE-L
> Subject: RE: flag
>
>
> Y/Null instead of Y/N worked really well for us. We had a
> multi-million row table that was often queried with the flag
> value and only returned a small number of rows based on the
> flag. An index was needed on the flag but if all rows
> contained a 'Y' or an 'N' then the index required a lot of
> overhead and quickly became stale and needed rebuilding. By
> changing the data to Y/Null instead of Y/N and rewriting the
> code just a little we had a much smaller index and
> performance didn't degrade. Using NULL for boolean operations
> works well because NULL is not nothin' ya know.
>
> - Steve
>
>
> -----Original Message-----
> Sent: Wednesday, May 21, 2003 9:07 PM
> To: Multiple recipients of list ORACLE-L
>
>
> I liked the idea of using 0/1 for Java Boolean operations
> but on the other side of the argument is that we inadvertently
> did a datatype transformation and ended up not using the
> index (Oracle implicitly converted the data side to number
> and failed to use the index, where we compared against
> a field defined, based on a table and the table had been
> created with wrong data type AAAaaargh.
>
> I much prefer Y/N. However because many of our
> applications (for Fed Govt) need to be bilingual,
> 1/0 is used (rather than worry about storing Oui/Non)
>
> - Babette
> -----Original Message-----
> Sent: Wednesday, May 21, 2003 8:28 PM
> To: Multiple recipients of list ORACLE-L
>
>
> If it's a Y/N flag (boolean) that needs to be indexed then
> you can just make
> it Y/NULL and handle it via code. This can substantially
> reduce the size of
> the index. (not talking about bitmap indexes now)
>
>
>
> -----Original Message-----
> Sent: Wednesday, May 21, 2003 3:48 PM
> To: Multiple recipients of list ORACLE-L
>
>
> Are you planning to use the flagged column as a boolean across a jdbc
> connection? If so, then go with a number datatype. The 9i
> jdbc driver does
> not know how to handle boolean datatype, thus if you store
> 'Y' in a char
> column the jdbc driver will throw errors when the java
> application calls
> GetBoolean against the jdbc driver.
>
> Mark
>
> -----Original Message-----
> Sent: Wednesday, May 21, 2003 1:17 PM
> To: Multiple recipients of list ORACLE-L
>
>
> Would you use a number or char for a flag in a table? Would you use a
> char since it's one byte and a number is 22 bytes?
>
> Dave
> --
> Please see the official ORACLE-L FAQ: http://www.orafaq.net
> --
> Author: David Turner
> INET: turner_at_tellme.com
>
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>
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> --
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> --
> Author: Orr, Steve
> INET: sorr_at_rightnow.com
>
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> --
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> --
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> --
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>
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-- Please see the official ORACLE-L FAQ: http://www.orafaq.net -- Author: gmei INET: gmei_at_incyte.com Fat City Network Services -- 858-538-5051 http://www.fatcity.com San Diego, California -- Mailing list and web hosting services --------------------------------------------------------------------- To REMOVE yourself from this mailing list, send an E-Mail message to: ListGuru_at_fatcity.com (note EXACT spelling of 'ListGuru') and in the message BODY, include a line containing: UNSUB ORACLE-L (or the name of mailing list you want to be removed from). You may also send the HELP command for other information (like subscribing). -- Please see the official ORACLE-L FAQ: http://www.orafaq.net -- Author: Igor Neyman INET: ineyman_at_perceptron.com Fat City Network Services -- 858-538-5051 http://www.fatcity.com San Diego, California -- Mailing list and web hosting services --------------------------------------------------------------------- To REMOVE yourself from this mailing list, send an E-Mail message to: ListGuru_at_fatcity.com (note EXACT spelling of 'ListGuru') and in the message BODY, include a line containing: UNSUB ORACLE-L (or the name of mailing list you want to be removed from). You may also send the HELP command for other information (like subscribing).Received on Thu May 22 2003 - 13:07:19 CDT
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