db-derby-dev mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From "TomohitoNakayama" <tomon...@basil.ocn.ne.jp>
Subject Re: [jira] Updated: (DERBY-252) polishing up idea of default value including auto increment of a column in table
Date Sun, 01 May 2005 05:59:46 GMT
Hello.

Modification was just correction of  words...

before:
Take aside

after:
Aside from

Best regards.

/*

         Tomohito Nakayama
         tomonaka@basil.ocn.ne.jp
         tomohito@rose.zero.ad.jp

         Naka
         http://www5.ocn.ne.jp/~tomohito/TopPage.html

*/
----- Original Message ----- 
From: "Tomohito Nakayama (JIRA)" <derby-dev@db.apache.org>
To: <derby-dev@db.apache.org>
Sent: Sunday, May 01, 2005 2:54 PM
Subject: [jira] Updated: (DERBY-252) polishing up idea of default value 
including auto increment of a column in table


>     [ http://issues.apache.org/jira/browse/DERBY-252?page=all ]
>
> Tomohito Nakayama updated DERBY-252:
> ------------------------------------
>
>    Description:
> This is not bug. However, there exists some complexity in the part of 
> default value and autoincrement value in current implementation of derby.
> Aside from whether any modification to be done or not for this issue, 
> polishing up the idea of default including autoincrement would be help 
> thinking about default and autoincrement.
>
>
> Next is my idea for default...
>
> "default value of the column" is value which registered to the column when 
> a record was inserted without any value.
>
> "default value of the column" can be one of the next.
>  def_1: default does not exist
>  def_2: constant value
>  def_3: generated by a rule
>  def_3-1: autoincrement value
>  def_3-2: value generated by more complex rule than autoincrement (This 
> does not exists in derby)
>
> There exists question wheter def_3 is truly default or not.
>
>
> In the current implementation of derby, object interfaced as 
> "org.apache.derby.catalog.DefaultInfo" was externalized to "COLUMNDEFAULT" 
> of "SYS_COLUMNS" in the case of def_2, and the object have information of 
> what constant value is used as default value.
> On the other hand, information about autoincrement value was stored to 
> "IDENTITYCOLUMNVALUE", "IDENTITYCOLUMNSTART", "IDENTITYCOLUMNINC" of 
> "SYS_COLUMNS".
>
> There exists question in the case of def_3, why information about 
> autoincrement value does not exist in DefaultInfo.
> One answer for this question is that storing information in 
> "IDENTITYCOLUMNVALUE" to DefaultInfo would cause performance trouble, 
> because this will cause re-storing all information of DefaultInfo always 
> when record was inserted and next autoincrement value was prepared.
> But this answer does not explan about information of 
> "IDENTITYCOLUMNSTART", "IDENTITYCOLUMNINC".
>
>
>  was:
> This is not bug. However, there exists some complexity in the part of 
> default value and autoincrement value in current implementation of derby.
> Take aside whether any modification to be done or not for this issue, 
> polishing up the idea of default including autoincrement would be help 
> thinking about default and autoincrement.
>
>
> Next is my idea for default...
>
> "default value of the column" is value which registered to the column when 
> a record was inserted without any value.
>
> "default value of the column" can be one of the next.
>  def_1: default does not exist
>  def_2: constant value
>  def_3: generated by a rule
>  def_3-1: autoincrement value
>  def_3-2: value generated by more complex rule than autoincrement (This 
> does not exists in derby)
>
> There exists question wheter def_3 is truly default or not.
>
>
> In the current implementation of derby, object interfaced as 
> "org.apache.derby.catalog.DefaultInfo" was externalized to "COLUMNDEFAULT" 
> of "SYS_COLUMNS" in the case of def_2, and the object have information of 
> what constant value is used as default value.
> On the other hand, information about autoincrement value was stored to 
> "IDENTITYCOLUMNVALUE", "IDENTITYCOLUMNSTART", "IDENTITYCOLUMNINC" of 
> "SYS_COLUMNS".
>
> There exists question in the case of def_3, why information about 
> autoincrement value does not exist in DefaultInfo.
> One answer for this question is that storing information in 
> "IDENTITYCOLUMNVALUE" to DefaultInfo would cause performance trouble, 
> because this will cause re-storing all information of DefaultInfo always 
> when record was inserted and next autoincrement value was prepared.
> But this answer does not explan about information of 
> "IDENTITYCOLUMNSTART", "IDENTITYCOLUMNINC".
>
>
>
>> polishing up idea of default value including auto increment of a column 
>> in table
>> --------------------------------------------------------------------------------
>>
>>          Key: DERBY-252
>>          URL: http://issues.apache.org/jira/browse/DERBY-252
>>      Project: Derby
>>         Type: Task
>>   Components: Documentation
>>     Reporter: Tomohito Nakayama
>>     Priority: Minor
>
>>
>>  This is not bug. However, there exists some complexity in the part of 
>> default value and autoincrement value in current implementation of derby.
>>  Aside from whether any modification to be done or not for this issue, 
>> polishing up the idea of default including autoincrement would be help 
>> thinking about default and autoincrement.
>> Next is my idea for default...
>>  "default value of the column" is value which registered to the column 
>> when a record was inserted without any value.
>>  "default value of the column" can be one of the next.
>>   def_1: default does not exist
>>   def_2: constant value
>>   def_3: generated by a rule
>>   def_3-1: autoincrement value
>>   def_3-2: value generated by more complex rule than autoincrement (This 
>> does not exists in derby)
>>  There exists question wheter def_3 is truly default or not.
>>  In the current implementation of derby, object interfaced as 
>> "org.apache.derby.catalog.DefaultInfo" was externalized to 
>> "COLUMNDEFAULT" of "SYS_COLUMNS" in the case of def_2, and the object 
>> have information of what constant value is used as default value.
>>  On the other hand, information about autoincrement value was stored to 
>> "IDENTITYCOLUMNVALUE", "IDENTITYCOLUMNSTART", "IDENTITYCOLUMNINC" of 
>> "SYS_COLUMNS".
>>  There exists question in the case of def_3, why information about 
>> autoincrement value does not exist in DefaultInfo.
>>  One answer for this question is that storing information in 
>> "IDENTITYCOLUMNVALUE" to DefaultInfo would cause performance trouble, 
>> because this will cause re-storing all information of DefaultInfo always 
>> when record was inserted and next autoincrement value was prepared.
>>  But this answer does not explan about information of 
>> "IDENTITYCOLUMNSTART", "IDENTITYCOLUMNINC".
>
> -- 
> This message is automatically generated by JIRA.
> -
> If you think it was sent incorrectly contact one of the administrators:
>   http://issues.apache.org/jira/secure/Administrators.jspa
> -
> For more information on JIRA, see:
>   http://www.atlassian.com/software/jira
>
>
>
>
> -- 
> No virus found in this incoming message.
> Checked by AVG Anti-Virus.
> Version: 7.0.308 / Virus Database: 266.11.0 - Release Date: 2005/04/29
>
> 



-- 
No virus found in this outgoing message.
Checked by AVG Anti-Virus.
Version: 7.0.308 / Virus Database: 266.11.0 - Release Date: 2005/04/29


Mime
View raw message