Command Line options for DP4 network programs.

This section summarises in table form the command tails available for and network requesters and manager respectively in all the operating environments supported. For further details on individual operating environments see the respective sections of this document. A few options that are rarely if ever used now have been omitted, but are documented on the platform specific pages. The command tails for AUXDISTR and SRVn are NOT listed here (they may be added in a later version). Please consult the pages that deal with loading specific network configurations.

DP4 programs do not usually complain if they are passed a spurious command tail. Therefore it is rather easy, especially in a resilience environment, to put a command tail on the wrong program.

Tails Used on Both Network Manager and Network Requester.

Network Requester command tails

Network manager command tails:

DP4 Terminal Client command tails:

Network Router (AUXDISTR) command tails

Automatic Reconciliation Program (ONLINE) command tails

-nofaster and -noblock Tails [4.520]

The information in this section applies for release prior to 4.621. These command tails have no effect on DP4 network requesters from version 4.621, both of the optimisations to which they were relevant have been removed - block fetch optimisations should be done using the bf_() functions in C/C++ code, and are done automatically by QAB and other DP4 utilities. The effect of the old block post optimisation is now automatically enabled on TCP/IP because DP4 no longer requires an immediate response from the server for calls to rec_post() or a number of other functions.

These command tails were not documented correctly in earlier releases. Prior to 4.520 -nofaster disabled both block fetch and block (queued) updates.

The network requester contains code to "queue" updates to the database in order to reduce the number of calls across the network, and code to "block fetch" records being fetched with a sequence of rec_fetch_main(NEXT) or rec_fetch_main(PREV) calls. This code can be disabled using -nofaster. The block fetch can be disabled with -noblock. Normally both these command tails are supplied to the network requester. When multiple resilience is used, the -noblock command tail should be specified on auxdistr instead. From 4.521/4.617 onwards, queued updates are automatically disabled when auxdistr is in use.

It is suspected that the former feature no longer improves performance significantly - (except during batch updates, where it can be quite effective) . The block fetch feature is potentially beneficial. However applications can perform block fetching more efficiently for themselves using the bf_fetch() family of functions. QAB does this for multiple choice access and also for sorts. However, these features are retained until such time as we can test a wide range of applications on different network configurations.

You are therefore recommended to experiment with loading the requester software with and without the -nofaster command tail and to use whichever configuration performs best. We would be interested to here whether performance is better with or without -nofaster.