2.4.1 Record Sets

The most basic property that can be specified for a set of records is their type. The special field name %rec is used for that purpose:

%rec: Entry

Id: 1
Name: Entry 1

Id: 2
Name: Entry 2

The records following the descriptors are then identified as having its type. So in the example above we would say there are two records of type “Entry”. Or in a more colloquial way we would say there are two “Entries” in the database.

The effect of a record descriptor ends when another descriptor is found in the stream of records. This allows you to store different kinds of records in the same database. For example, suppose you are maintaining a depot. You will need to keep track of both what items are available and when they are sold or restocked.

The following example shows the usage of two record descriptors to store both kind of records: articles and stock.

%rec: Article

Id: 1
Title: Article 1

Id: 2
Title: Article 2

%rec: Stock

Id: 1
Type: sell
Date: 20 April 2011

Id: 2
Type: stock
Date: 21 April 2011

The collection of records having same types in recfiles are known as record sets in recutils jargon. In the example above two record sets are defined: one containing articles and the other containing stock movements.

Nothing prevents having empty record sets in databases. This is in fact usually the case when a new recfile is written but no data exists yet. In our depot example we could write a first version of the database containing just the record descriptors:

%rec: Article

%rec: Stock

Special records are not required, and many recfiles do not have them. This is because all the records contained in the file are of the same type, and their nature can usually be inferred from both the file name and their contents. For example, contacts.rec could simply contain records representing contacts without an explicit %rec: Contact record descriptor. In this case we say that the type of the anonymous records stored in the file is the default record type.

Another possible situation, although not usual, is to have a recfile containing both non-typed (default) and typed record types:

Id: 1
Title: Blah

Id: 2
Title: Bleh

%rec: Movement

Date: 13-Aug-2012
Concept: 20

Date: 24-Sept-2012
Concept: 12

In this case the records preceding the movements are of the “default” type, whereas the records following the record descriptor are of type Movement. Even though it is supported by the format and the utilities, it is generally not recommended to mix non-typed and typed records in a recfile.