Conversion

Hi,
I am in the process writing scripts for CHAR/VARCHAR to
NCHAR/NVARCHAR conversion..Infact i have completed
it..When I run these scripts against DB is verly
slow..This is happening when i run convert scripts
eaxctly..Even select name from sysobjects doesn't return
values..There are heavy IO is going on the DB..what are
the areas i should concentrate the to improve performance..
Basically I have written cursor whic executes one by one
the alter scripts..
Sridhar...Can you tell us how you are performing the upgrade i.e.
Have a different database or are you performing an alter
column ?
Thanks
Peter
>--Original Message--
>Hi,
> I am in the process writing scripts for CHAR/VARCHAR
to
>NCHAR/NVARCHAR conversion..Infact i have completed
>it..When I run these scripts against DB is verly
>slow..This is happening when i run convert scripts
>eaxctly..Even select name from sysobjects doesn't return
>values..There are heavy IO is going on the DB..what are
>the areas i should concentrate the to improve
performance..
>
>Basically I have written cursor whic executes one by one
>the alter scripts..
>
>Sridhar...
>.
>|||By alter columns...
>--Original Message--
>Can you tell us how you are performing the upgrade i.e.
>Have a different database or are you performing an alter
>column ?
>Thanks
>Peter
>>--Original Message--
>>Hi,
>> I am in the process writing scripts for CHAR/VARCHAR
>to
>>NCHAR/NVARCHAR conversion..Infact i have completed
>>it..When I run these scripts against DB is verly
>>slow..This is happening when i run convert scripts
>>eaxctly..Even select name from sysobjects doesn't return
>>values..There are heavy IO is going on the DB..what are
>>the areas i should concentrate the to improve
>performance..
>>
>>Basically I have written cursor whic executes one by one
>>the alter scripts..
>>
>>Sridhar...
>>.
>.
>|||Changing a CHAR to VARCHAR will most likely involve each row being affected
and hence all the I/O. If you are altering more than one column per table
you might get better performance by creating a second table with the changed
columns and Inserting all the rows into it. Drop the original, rename the
new to the old and add the appropriate indexes, RI etc.. Just make sure you
have good backups first.
--
Andrew J. Kelly SQL MVP
<anonymous@.discussions.microsoft.com> wrote in message
news:297601c47e07$62bd4ae0$a501280a@.phx.gbl...
> Hi,
> I am in the process writing scripts for CHAR/VARCHAR to
> NCHAR/NVARCHAR conversion..Infact i have completed
> it..When I run these scripts against DB is verly
> slow..This is happening when i run convert scripts
> eaxctly..Even select name from sysobjects doesn't return
> values..There are heavy IO is going on the DB..what are
> the areas i should concentrate the to improve performance..
>
> Basically I have written cursor whic executes one by one
> the alter scripts..
>
> Sridhar...
>|||Consider what Andrew has said, but also regardless of
which way you are doing it take off all indexes before you
start.
How many rows of data are you converting ?
>--Original Message--
>By alter columns...
>>--Original Message--
>>Can you tell us how you are performing the upgrade i.e.
>>Have a different database or are you performing an alter
>>column ?
>>Thanks
>>Peter
>>--Original Message--
>>Hi,
>> I am in the process writing scripts for CHAR/VARCHAR
>>to
>>NCHAR/NVARCHAR conversion..Infact i have completed
>>it..When I run these scripts against DB is verly
>>slow..This is happening when i run convert scripts
>>eaxctly..Even select name from sysobjects doesn't
return
>>values..There are heavy IO is going on the DB..what are
>>the areas i should concentrate the to improve
>>performance..
>>
>>Basically I have written cursor whic executes one by
one
>>the alter scripts..
>>
>>Sridhar...
>>.
>>.
>.
>