On 07/07/2022 16:19, Lorenz Buehmann wrote:
I think we should wait for Andy here with further input as he's the
persons who basically designed and implemented all the fancy stuff and
knows better advice for sure.
@Andy Did you read the whole discussion and can you verify that it's
expected behavior that lot's of daily updates lead to such a big growth
of the node table files?
Sorry for the delay.
There is no Lucene index by default.
SPO.dat is not nodes table related - it is the base level of the SPO
B+Tree. SPO.idn is the tree above the base level and SPO.bpt keeps the
pointers to the root block and some size information.
The issue looks to be the large numbers of small updates. TDB2 used a
copy-by-write MVCC scheme which means transactions can proceed without
needing latches (database locks) but has the consequence of needing
compaction.
TDB1 with Fuseki is worth a try. It does not use the scheme. It does
grow but much more slowly. It is limited in the size of updates it can
handle but the limit is no where near what you describe.
Also worth trying is compaction and deletion
/$/compact/db_name?deleteOld=true
which will delete the old database after compaction (only the one just
compacted. Old ones can be manually deleted).
Andy
On 07.07.22 10:53, Bartalus Gáspár wrote:
Hi Lorenz,
Would you recommend using tdb1 instead of tdb2 for our use case? What
would be the differences?
We are using fuseki 4.5.0 btw.
Gaspar
On 6 Jul 2022, at 14:39, Bartalus Gáspár
<[email protected]> wrote:
Hi,
Most of the updates are DELETE/INSERT queries, i.e
DELETE {?s ?p ?oldValue}
INSERT {?s ?p ?newValue}
WHERE {
OPTIONAL {?s ?p ?oldValue}
#derive ?newValue from somewhere
}
We also have some separate DELETE queries and INSERT queries.
I’ve tried HTTP POST /$/compact/db_name and as a result the files are
getting back to normal size. However, as far as I can tell the old
files are also kept. This is the folder structure I see:
- databases/db_name/Data-0001 - with the old large files
- databases/db_name/Data-0002 - presumably the result of the compact
operation with normal file sizes.
Is there also some operation (http or cli) that would keep only one
(the latest) data folder, i.e. delete the old files from Data-0001?
Gaspar
On 6 Jul 2022, at 12:52, Lorenz Buehmann
<[email protected]> wrote:
Ok, interesting
so
we have
- 150k triples, rather small dataset
- loaded into 10MB node table files
- 10 updates every 5s
- which makes up to 24 * 60 * 60 / 5 * 10 ~ 200k updates per day
- and leads to 10GB node table files
Can you share the shape of those update queries?
After doing a "compact" operation, the files are getting back to
"normal" size?
On 06.07.22 10:36, Bartalus Gáspár wrote:
Hi Lorenz,
Thanks for quick feedback and clarification on lucene indexes.
Here are my answers to your questions:
- We are uploading 7 ttl files to our dataset, where 1 is larger
6Mb, the others are below 200Kb.
- The overall number of triples after data upload is ~150000.
- We have around 10 SPARQL UPDATE queries that are executed on a
regular and frequent basis, i.e. every 5 seconds. We also have 5
such queries that are executed each minute. But most of the time
they do not produce any outcome, i.e. the dataset is not altered,
and when they do, there are just a couple of triples that are added
to the dataset.
- These *.dat files start from ~10Mb in size, and after a day or so
some of them grow to ~10Gb.
We have ~300 blank nodes, and ~half of the triples have a literal
in the object position, so ~75000.
Best regards,
Gaspar
On 6 Jul 2022, at 10:55, Lorenz Buehmann
<[email protected]> wrote:
Hi and welcome Gaspar.
Those files do contain the node tables.
A Lucene index is never computed by default and would be contained
in Lucene specific index files.
Can you give some details about the
- size of the files
- the number of triples
- the number triples added/removed/changed
- the frequency of updates
- how much the files grow
- what kind of data you insert? Lots of blank nodes? Or literals?
Also, did you try a compact operation during time?
Lorenz
On 06.07.22 09:40, Bartalus Gáspár wrote:
Hi Jena support team,
We are experiencing an issue with Jena Fuseki databases. In the
databases folder we see some files called SPO.dat, OSP.dat, etc.,
and the size of these files are growing quickly. From our
understanding these files are containing the Lucene indexes. We
would have two questions:
1. Why are these files growing rapidly, although the underlying
data (triples) are not being changed, or only slightly changed?
2. Can we disable indexing easily, since we are not using full
text searches in our SPARQL queries?
Our usage of Jena Fuseki:
* Start the server with `fuseki-server —port 3030`
* Create databases with HTTP POST to
`/$/datasets?state=active&dbType=tdb2&dbName=db_name`
* Upload ttl files with HTTP POST to /db_name/data
Thanks in advance for your feedback, and if you’d require more
input from our side, please let me know.
Best regards,
Gaspar Bartalus
