Sunday, September 26, 2010

Move Object Layer

This was one interesting excercise we did where we moved the objects from the VAR layer to the BUS layer for one of the live implementations. The challenge was that we wanted to retain all the data and all the references.

1. To begin with we had two installations once was the dev instance where the objects were in the bus layer and the other was the live instance where the objects were in the var layer.

2. We know that while the no sequence of the objects starts from 30000 onwards in the var layer it starts from 20000 onwards in the bus layer. So once we resoted the bus layer (aod) the existing object id's in the 30,000 series became irrelevant. So we deleted all the entries in the sql dictionary table between 30000 and 40000, backup the records from the dev environment where tableid was between 20000 and 30000and restored it on the live.

3. We also know that when the table names are more than 30 chars the synchronize routine replaces the last 4 chars of the table with the objectid. So we manully looked for such objects and changed the tableid suffix in such objects from the 30000 series to the 20000 series.

4. Once we did the above we were getting a duplicate record while entering data into most of the table it was no long before we realized that the systemsequences table contains the last record id and is used to generate the record if for the new record. In this case as the object ids changed a corresponding entry for them was required in the systemsequences table with the new object ids. I wrote a script to generate a script for the right updates.

select ' insert into systemsequences
+ 'select '
+ ' -1, isnull( max( recid ) + 1, 1 ) , 1, 9223372036854775807, 0, ''SEQNO'', ' + cast( SD.TableID as varchar) + ',''dat'', 1, -1'
+ ' from ' + SD.SQLName
from sqldictionary SD
left join systemsequences SS
on SS.tabid = SD.tableID
where 1=1
and SS.Name is null
and SD.tableid between 20000 and 30000
and SD.fieldid = 0

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