Preparing to Downgrade Adaptive Server

Prepare your system before starting the downgrade.

Note: If you are downgrading to Adaptive Server 15.7 ESD #1, which supports features such as compression and in-row LOB, skip the steps in this section.

Before you begin downgrading Adaptive Server, perform these steps for the features or configurations you enabled in Adaptive Server 15.7 SP100.

If the logical page size for your Adaptive Server is larger than 8192 bytes and you have configured any databases to allow wide data-only-locked (DOL) rows, turn the option off:
```
sp_dboption @dbname, 'allow wide dol rows', false
```
Before you downgrade Adaptive Server, verify that no wide DOL rows exist in any table in these databases. Adaptive Server cannot find them, and thus does not warn you about their existence. When you then downgrade to a version earlier than 15.7 SP100, Adaptive Server treats these as corrupt.

This does not occur if your logical page size is 8192 bytes or smaller.
If you have configured any database to use either row or page compression, turn it off:
```
alter database @dbname set compression none
```
If any database has nonzero, in-row large object (LOB) lengths, set it to zero:
```
alter database @dbname set inrow_lob_length = 0
```

If any table is configured to use compression, turn it off:

alter table @tablename set compression = none
reorg rebuild @tablename

If any table uses LOB compression or in-row LOBs:
1. Copy the data from that table to a new table.
2. Drop the original table.
If any table was altered to include nonmaterialized columns, convert those columns to standard columns:
```
reorg rebuild @tablename
```
If there are any holes in the database from previous alter database off commands, remove the holes by using alter database on to extend the database.
If you do not perform this before the downgrade, you see a message similar to:
```
Error: Database 'dbname' contains num hidden pages that have to be filled. 
Please, use ALTER DATABASE ON command to extend the database by num pages.
```
You can extend the database on any data device, as long as you specify the number of indicated pages as being at least as large as the num value.