Why does dbmopen create two files?

Anonymous Monk has asked for the wisdom of the Perl Monks concerning the following question:

When I create a database using dbmopen, e.g.

dbmopen( %DB, $datapathname, 0666 ) or die;
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dbm creates two files rather one:

data.dir
data.pag
[download]

Why is that?

Originally posted as a Categorized Question.

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Re: Why does dbmopen create two files? by belg4mit (Prior) on Dec 18, 2006 at 11:43 UTC
One contains the actual data ("page") table, the other is an index ("directory").	[reply]
Re: Why does dbmopen create two files? by merlyn (Sage) on Sep 27, 2000 at 11:14 UTC
That's either ODBM or NDBM. GDBM introduced the idea of a single `.db` file rather than the pair of files used by DBMs since the early 1980s.	[reply]