• The 6.4 QEF sorting algorithm is unsuited to large qef_sort_mem settings. All recent Ingres versions use a different sort that does not degrade with large qef_sort_mem settings. The 6.4 standard setting is much smaller than the Ingres default.

• Recent Ingres versions typically require significantly less qsf_memory than Ingres 6.4 does, perhaps as little as half. After upgrading, start with the same qsf_memory setting as Ingres 6.4, but monitor QSF memory usage with trace point QS501 and tune qsf_memory appropriately.

• The quantum_size parameter in an internal threads (slaves) installation is often set to a small number (50 to 100) to improve responsiveness. Quantum_size has a different meaning in an OS threads installation, where it should not be set to less than 300, or excessive polling of the session communications channel will occur. A quantum_size of 1000 is usually appropriate when OS threads are in use.

• The 6.4 write_behind parameter is a thread count. Starting with 2.5, the dmf_write_behind parameter is simply ON or OFF, and the server dynamically allocates threads. Prior to Ingres II 2.5, the write_behind parameter means the same as it did in 6.4.

• A stack_size of 64 KB is typical with 6.4. Recent Ingres versions use more stack, so the stack size should be set to 128 KB (or more, if sporadic session failures occur).

• 6.4 VMS installations can have a few additional non-UNIX parameters, which have the same or almost the same names in recent Ingres versions.