The text below is excerpted from a post I made on the
hts_users group. The subject was about the problem of getting
a "timeout" while using MvPACK on large DBIII files. This led
to a discussion on ways to keep from MvPACKing in the first
place.

=============================================================
From:             "Brian R. Bullock" <brian@wwwebweaver.com>
To:               hts-users <hts-users@htmlscript.com>
Subject:          Re: MvPACK'ing and large databases
Date sent:        Mon, 7 Sep 1998 14:39:13 +0000

<snip>

For offline DBs you can set the Miva Mia timeout to zero(no timeout).

For online DBs there are two reasons to MvPACK.

1) Removing deleted records.
  Bill Wieland's suggestion (which I use religiously) is to
re-use deleted records. The d.deleted variable is a built-in
Miva variable just like d.eof, d.recno, d.totrec, etc. It is
automatically set to true for a record when you use MvDELETE
on the record. You should already be using the d.deleted
variable to exclude deleted records from display. So when you
need to add a new record just use a function based on the
skeleton function below:

<MvFUNCTION
 NAME= "Add2DB"
 STANDARDOUTPUTLEVEL= "">
<MvOPEN NAME= "yourDB"
 DATABASE= "path/to/yourDB.dbf"
 INDEXES= "Open ALL that might change">
>>>>Code to assign ALL db variables<<<<
<MvFILTER
 NAME= "yourDB"
 FILTER= "{d.deleted}">
<MvIF EXPR= "{d.eof}">
  <MvADD NAME= "yourDB">
<MvELSE>
  <MvUPDATE NAME= "yourDB">
</MvIF>
<MvCLOSE NAME= "yourDB">
</MvFUNCTION>

To control db field "bleed-through" you should assign a value
to ALL db fields (even if only a null) when using MvADD or
MvUPDATE to add a new record.

2) To reduce the size of a .dbt file.
  When you change a MEMO field by assigning a value to it Miva
appends the new value to the end of the .dbt file. This happens
EVERY time you assign a value to the MEMO field even if that
value is the same as the previous value of the field. There are
two ways to control the .dbt file size. The first is proactive
and is accomplished by using this type of code in your db MEMO
field variable assignments when updating a record:

<MvIF EXPR= "{d.memofield  NE gmemofield}">
  <MvASSIGN NAME= "d.memofield" VALUE= "{gmemofield}">
</MvIF>

The other way is reactive by using MvPACK. This removes all
but the current MEMO value from the .dbt file.

<snip>