ROWID columns

Informix®

When creating a table, Informix automatically adds a ROWID integer column (applies to non-fragmented tables only).

The ROWID column is auto-filled with a unique number and can be used like a primary key to access a given row.

Note:

Informix ROWID usage was a common practice in the early days of Informix 4GL programming. Today it is recommended to define all your database tables with a PRIMARY KEY to uniquely identify rows.

With Informix, the sqlca.sqlerrd[6] register contains the ROWID of the last row affected by an INSERT, UPDATE or DELETE statement.

Dameng®

Dameng support ROWID column, but the data type is different from Informix ROWIDs: Dameng rowids are CHAR(18).

For example:
AAAA8mAALAAAAQkAAA

Dameng rowids represent the physical addresses of the row, and cannot be used as permanent row identifiers: After a DELETE, an INSERT statement might reuse the physical place of the deleted row, to store the new row. However, rowids can be used in the context of a transaction.

For example:

Solution

If your Genero BDL application uses rowid columns, review the program logic to use primary keys insead. If the database table does no define a primary key, it should be added. All references to SQLCA.SQLERRD[6] must be removed, because this variable will not hold the ROWID of the last modified row.

To hold Dameng rowids, the type of variables containing ROWID values must be changed to CHAR(18).
Tip:

Informix INTEGER rowids fit in a CHAR(18) variable. If you adapt the code to use CHAR(18) rowids, the code will still work with Informix database.

When connected to a Dameng database, all references to sqlca.sqlerrd[6] must be reviewed, because this register can not contain the rowid of the last affected row.

For databases where the keyword of the rowid pseudo-column is different than "ROWID", the translation can be controlled with the following FGLPROFILE entry:
dbi.database.dsname.ifxemul.rowid = { true | false }
For more details see IBM Informix emulation parameters in FGLPROFILE.