Hi,
There's no fundamental problem with storing numeric data in an RDF
database, even though that's not the design centre. After all the Data
Cube vocabulary is basically just a way to do that and it gets heavy use
for statistical and sensor data.
However, writing ~1MTriples can take ~10s in a live TDB. Bulk load to an
empty database is faster.
For real use you should wrap your write block in a dataset.begin/commit
block, though that doesn't make much difference to the timing.
Dave
On 08/06/16 08:00, Martin Gütlein wrote:
Thanks for your response.
We are developing a system that includes prediction models in the
cheminformatics domain. So there is a lot of (cheminformatics) data that
is stored in our database and fits very well into it. We are not sure
about the numeric data below, though. But we want to have it all in a
single database (and avoid storing sth on the file system or in an
additional sql database, if possible).
Kind regards,
Martin
Am 07.06.2016 um 21:54 schrieb A. Soroka:
This seems like a bit of an odd usage for an RDF store. Could you
explain a bit more why you want to put this data into Jena? Are you
already using Jena for other data in your work?
---
A. Soroka
The University of Virginia Library
On Jun 7, 2016, at 11:22 AM, Martin Gütlein <[email protected]>
wrote:
Hi,
we would like to store some tables with double values in our triple
store. At the moment we are doing this by creating row and entry
resources (see code below).
However, it is rather time and space consuming for medium sized
tables. E.g. a 500x500 table takes 20seconds and the the db size is
156MB. For our project we plan to save larger/more data (and add some
more semantic info).
Is there a more efficient way to do that?
Kind regards,
Martin
Here is our example code:
int cols = 500;
int rows = 500;
double myTable[][] = new double[rows][cols];
for (int r = 0; r < rows; r++)
for (int c = 0; c < cols; c++)
myTable[r][c] = new Random().nextDouble();
String directory = "myDB/tdb";
Dataset dataset = TDBFactory.createDataset(directory);
Model model = dataset.getDefaultModel();
String NS = "http://my-namespace/test/";;
Property hasRow = model.createProperty(NS + "hasRow");
Property rowIndex = model.createProperty(NS + "rowIndex");
Property hasEntry = model.createProperty(NS + "hasEntry");
Property colIndex = model.createProperty(NS + "colIndex");
Property value = model.createProperty(NS + "value");
Resource table = model.createResource(NS + "table/" +
UUID.randomUUID());
for (int r = 0; r < rows; r++)
{
Resource row = model.createResource(NS + "row/" +
UUID.randomUUID());
table.addProperty(hasRow, row);
row.addProperty(rowIndex, r + "", XSDDatatype.XSDint);
for (int c = 0; c < cols; c++)
{
Resource entry = model.createResource(NS + "entry/" +
UUID.randomUUID());
row.addProperty(hasEntry, entry);
entry.addProperty(colIndex, c + "", XSDDatatype.XSDint);
entry.addProperty(value, myTable[r][c] + "",
XSDDatatype.XSDdouble);
}
}
dataset.end();
dataset.close();
--
Dr. Martin Gütlein
Phone:
+49 (0)6131 39 23336 (office)
Email:
[email protected]
