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.

ORACLE

Oracle® supports ROWID columns, but the data type is different from Informix ROWIDs: Oracle rowids are CHAR(18).

For example:

AAAA8mAALAAAAQkAAA

Since Oracle rowids are physical addresses, they 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.

The Oracle Call Level (OCI) provides functions to get the rowid of the last row related to an INSERT, UPDATE, DELETE statement, ora FETCH of a cursor declared with a SELECT FOR UPDATE.

Solution

If your Genero BDL application uses Informix rowid columns, review the program logic to use the primary keys when available, or use Oracle rowids.

To hold Oracle 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 an Oracle database, all references to sqlca.sqlerrd[6] must be reviewed, because this register can not contain the rowid of the last affected row. However, after an INSERT, UPDATE or DELETE statement, or after a FETCH of a cursor declared with a SELECT FOR UPDATE, the sqlca.sqlerrm register is filled with the character extended (base 64) representation of the rowid of the last affected or fetched row.

Note:

The sqlca.sqlerrm register only contains a single rowid, even if multiple rows were affected by the INSERT, UPDATE or DELETE statement.

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.