Laura,
HDT does not provide update.
So it can keep compressed datastructures. In fact, it uses as much
compression as it can regardless of the need for update. Updating such
compressed (by content) datastructures would be very expensive (e.g. the
dictionary changes).
Andy
On 26/11/17 16:44, Laura Morales wrote:
HDT does actually create more indices "out of band", that it they create a
separate file.hdt.index files. The combined size however is still much smaller than a TDB
store of the same file, but I don't know if this is down to TDB simply having more
indices.
Sent: Sunday, November 26, 2017 at 5:20 PM
From: ajs6f <aj...@apache.org>
To: users@jena.apache.org
Subject: Re: Estimating TDB2 size
You have to start with the understanding that the indexes in a database are not
the same thing nor for the same purpose as a simple file of triples or quads.
TDB1 and 2 store the same triple several times in different orders (SPO, OPS,
etc.) in order to be able to answer arbitrary queries with good performance,
which is a common technique.
There is no reason to expect a database that is capable of answering arbitrary
queries with good performance to be as small as a file, which is not.
ajs6f
