OpenEdge Data Management: DataServer for Microsoft SQL Server

Defining the ROWID
Modifying a schema holder
When you create or update a schema holder, the DataServer uses the following
guidelines to select a column in a data source table to support the ROWID function:
• If the data source table has a PROGRESS_RECID column, the DataServer selects
that column. A column of this type provides optimal support for the ROWID function;
you cannot select an alternative to it. To create a PROGRESS_RECID column, see
the “Using triggers to enable PROGRESS_RECID support of the ROWID
function” section on page 313.
• If the data source table does not have a PROGRESS_RECID column, the DataServer
evaluates the available indexes and selects one according to the following criteria:
– The index must be defined as unique.
– The index must be defined as mandatory, or at least treated as such by your
application.
The index selection process proceeds, according to the following order:
1. If you select an index, then you must select a qualified index.
2. If you do not select an index, the MS SQL Server DataServer selects a qualified
index based on a single-component integer.
However, if the DataServer determines that more than one qualified index meets
the additional criterion as a single-component integer, the DataServer selects the
first index that fulfills the complete criteria.
3. If the MS SQL Server DataServer cannot find a qualified index based on a
single-component integer, it seeks a qualified index that is multi-component
and/or non-integer.
However, if the DataServer determines that more than one qualified index meets
the additional criterion as multi-component and/or non-integer, the DataServer
selects the first index that fulfills the complete criteria.
4. If the MS SQL Server DataServer cannot find a qualified index that is a
multi-component and/or non-integer, the task cannot be completed and ROWID
support is not provided. The table will not be able to uniquely identify any records.
As a result, implementing FIND statements and performing queries could lead to
inaccuracies in locating records.
Note that the indexes in this class are not mandatory; therefore, it is essential that you
enforce the column supporting ROWID as mandatory at least through code if not through
definitions.
The DataServer allocates a buffer to hold the key information for the selected RECID
index. The buffer is 245 bytes by default. If the index you select for the RECID is a
multi-component index, this may be inadequate. The size of the buffer can be modified
with the -Dsrv ZPRGRS_RECID_BUF_SIZE,n option. See the “RECID Buffer size—the
ZPRGRS_RECID_BUF_SIZE,nnn Option” section on page 329 for more information
on setting this option.
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