barry@primerd.prime.com (03/08/90)
For a number of years I've been maintaining a large database (about 5K
records) on a Prime minicomputer using Prime Information (Prime's
version of the Pick DBMS). Prime Information and Pick are
pseudo-relational databases that use hashed access to variable length
records. In a properly structured database, any record can be retrieved
in at most one disk read. The number of fields can vary from record to
record as can the datatype and length of any field. New fields can be
added to a database at any time. When a record is modified, the new
field values aren't constrained by the previous values in the field.
I'm not sure of the maximum length for a field, but it's at least 32K
characters. All of these characteristics make Prime Information (or
Pick) very well suited to maintaining a database where the fields are
mostly strings that vary widely in length, e.g. between 10 and 400
characters, approximately for my database.
The retrievals done on this database are of the form
list records with field1 like "...string..."
and field2 eq "a string" ...
with various sorting options ('field like "...value..."' means field
contains "value" as a substring). The retrieval language is comparable
to a subset of SQL.
One other feature of PI and Pick that is used in this database is
repeating fields. A repeating field is one that can have 1-N instances
it it. In effect, a repeating field is an array. The key point is the
user doesn't specify an upper bound. For all practical purposes, the
limit is infinite - it's at least 32K.
I'd like to move this database to my Mac where access to it will be much
more convenient. I've inherited a copy of Fox/Base Mac from a colleague
who left the company and I've skimmed thru the Fox/Base manuals. Since
Fox/Base requires fixed length fields, it doesn't appear appropriate to
my needs. Fox/Base has a memo data type that allows very long strings,
but it seems to be a second class citizen as far as searching is
concerned. I couldn't find anything that appears comparable to
repeating fields.
I'm looking for suggestions on what Mac databases would be appropriate.
The articles I've seen in MacWorld and MacUser don't indicate which Mac
DBMSs require fixed format records and which, if any, allow variable
length records or repeating fields of the sort described above.
Thus far, Filemaker II seems to be the most appropriate choice. I'd
appreciate hearing from anyone who's used Filemaker II (or anyother
relevant DBMS) for a mostly textual database. Is Fourth Dimension
overkill?
I'll post a summary if the replies appear to be of general interest.
Thanks in advance for your help,
Barry
------------------------------------------------------------------------
Barry Wolman | barry@s66.prime.com
Principal Technical Consultant | 500 Old Connecticut Path
Prime Computer | Framingham, MA 01701
| 508/879-2960, ext. 1100
------------------------------------------------------------------------
Nothing in this posting reflects a position of Prime Computer.
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