Re: read-only Fuseki TDB2
While in TDB2, read-transactions never write, there is a case where a
read-only setup needs to do writes.
It happens only at start-up and only the first time after the database
is written during setup.
If there is a journal file with outstanding changes, these are completed
before the database is passed to the application. It means there was an
abnormal termination during the last write transaction after the commit
point. The timing window for that is quite small.
A simple way is to prepare a database is to do a query on it as a
separate process after it's been written : e.g.
tdb2.tdbquery --loc DATABASE 'ASK{}'
TDB1 is different; read-transactions can do some completion actions. The
journal is more heavily used.
Andy
On 18/09/2023 16:35, Jim Balhoff wrote:
On Sep 18, 2023, at 11:09 AM, Andy Seaborne wrote:
On 18/09/2023 15:35, Jim Balhoff wrote:
Thanks, I think that’s basically what I’ve got. The only operation I have
enabled is 'fuseki:query’. But Fuseki still complains if the filesystem is
read-only.
The database is opened before the configuration is processed.
Also, there is only one "database" java object for each database location and
something elsewhere may now or later open it for other operations.
This could be changed - file management is (should be!) centralized in the
codebase.
Got it, thanks. It isn’t too big of a problem; it would just be convenient for
some situations like scaling up multiple servers in Kubernetes.
Re: read-only Fuseki TDB2
> On Sep 18, 2023, at 11:09 AM, Andy Seaborne wrote: > > > > On 18/09/2023 15:35, Jim Balhoff wrote: >> Thanks, I think that’s basically what I’ve got. The only operation I have >> enabled is 'fuseki:query’. But Fuseki still complains if the filesystem is >> read-only. > > The database is opened before the configuration is processed. > > Also, there is only one "database" java object for each database location and > something elsewhere may now or later open it for other operations. > > This could be changed - file management is (should be!) centralized in the > codebase. > > Got it, thanks. It isn’t too big of a problem; it would just be convenient for some situations like scaling up multiple servers in Kubernetes.
Re: read-only Fuseki TDB2
On 18/09/2023 15:35, Jim Balhoff wrote: Thanks, I think that’s basically what I’ve got. The only operation I have enabled is 'fuseki:query’. But Fuseki still complains if the filesystem is read-only. The database is opened before the configuration is processed. Also, there is only one "database" java object for each database location and something elsewhere may now or later open it for other operations. This could be changed - file management is (should be!) centralized in the codebase. Andy On Sep 18, 2023, at 10:03 AM, Martynas Jusevičius wrote: This looks like the configuration that you need: https://jena.apache.org/documentation/fuseki2/fuseki-configuration.html#read-only-service On Mon, Sep 18, 2023 at 2:43 PM Jim Balhoff wrote: Hi, Is it possible to run a Fuseki server using a read-only TDB2 directory? I’d like to run a query-only SPARQL endpoint, no updates. However I get an exception at startup if the filesystem is read-only. Does Fuseki need to acquire the lock even if updates are turned off? Thank you, Jim
Re: read-only Fuseki TDB2
Thanks, I think that’s basically what I’ve got. The only operation I have enabled is 'fuseki:query’. But Fuseki still complains if the filesystem is read-only. > On Sep 18, 2023, at 10:03 AM, Martynas Jusevičius > wrote: > > This looks like the configuration that you need: > https://jena.apache.org/documentation/fuseki2/fuseki-configuration.html#read-only-service > > On Mon, Sep 18, 2023 at 2:43 PM Jim Balhoff wrote: >> >> Hi, >> >> Is it possible to run a Fuseki server using a read-only TDB2 directory? I’d >> like to run a query-only SPARQL endpoint, no updates. However I get an >> exception at startup if the filesystem is read-only. Does Fuseki need to >> acquire the lock even if updates are turned off? >> >> Thank you, >> Jim >>
Re: read-only Fuseki TDB2
This looks like the configuration that you need: https://jena.apache.org/documentation/fuseki2/fuseki-configuration.html#read-only-service On Mon, Sep 18, 2023 at 2:43 PM Jim Balhoff wrote: > > Hi, > > Is it possible to run a Fuseki server using a read-only TDB2 directory? I’d > like to run a query-only SPARQL endpoint, no updates. However I get an > exception at startup if the filesystem is read-only. Does Fuseki need to > acquire the lock even if updates are turned off? > > Thank you, > Jim >
Re: read-only Fuseki TDB2
The TDB2 database is open for general use (i.e. write). You can get read-only by restricting the operations on the dataset to only query and the read functions of the Graph Store Protocol. Being SPARQL, query operations and write (update) operations are separate by syntax and there are different parsers for each subset of the total SPARQL grammar. Andy On 18/09/2023 13:40, Jim Balhoff wrote: Hi, Is it possible to run a Fuseki server using a read-only TDB2 directory? I’d like to run a query-only SPARQL endpoint, no updates. However I get an exception at startup if the filesystem is read-only. Does Fuseki need to acquire the lock even if updates are turned off? Thank you, Jim
Re: read-only Fuseki TDB2
I think it depends more on query than with the back end, but don't have detailed comparisons. Perhaps others do. On Mon, 18 Sept 2023, 14:43 Jim Balhoff, wrote: > Thanks, maybe that would be a good fit. Do you know how query performance > compares running over HDT compared to TDB2? Or is that question is too > dependent on the particular queries to answer? > > > On Sep 18, 2023, at 8:51 AM, Pedro > wrote: > > > > Jim > > Perhaps https://www.rdfhdt.org/manual-of-hdt-integration-with-jena/ will > > suit your need. > > Cheers > > Peter > > > > On Mon, 18 Sept 2023, 13:43 Jim Balhoff, wrote: > > > >> Hi, > >> > >> Is it possible to run a Fuseki server using a read-only TDB2 directory? > >> I’d like to run a query-only SPARQL endpoint, no updates. However I get > an > >> exception at startup if the filesystem is read-only. Does Fuseki need to > >> acquire the lock even if updates are turned off? > >> > >> Thank you, > >> Jim > >> > >> > >
Re: read-only Fuseki TDB2
Thanks, maybe that would be a good fit. Do you know how query performance compares running over HDT compared to TDB2? Or is that question is too dependent on the particular queries to answer? > On Sep 18, 2023, at 8:51 AM, Pedro > wrote: > > Jim > Perhaps https://www.rdfhdt.org/manual-of-hdt-integration-with-jena/ will > suit your need. > Cheers > Peter > > On Mon, 18 Sept 2023, 13:43 Jim Balhoff, wrote: > >> Hi, >> >> Is it possible to run a Fuseki server using a read-only TDB2 directory? >> I’d like to run a query-only SPARQL endpoint, no updates. However I get an >> exception at startup if the filesystem is read-only. Does Fuseki need to >> acquire the lock even if updates are turned off? >> >> Thank you, >> Jim >> >>
Re: read-only Fuseki TDB2
Jim Perhaps https://www.rdfhdt.org/manual-of-hdt-integration-with-jena/ will suit your need. Cheers Peter On Mon, 18 Sept 2023, 13:43 Jim Balhoff, wrote: > Hi, > > Is it possible to run a Fuseki server using a read-only TDB2 directory? > I’d like to run a query-only SPARQL endpoint, no updates. However I get an > exception at startup if the filesystem is read-only. Does Fuseki need to > acquire the lock even if updates are turned off? > > Thank you, > Jim > >
read-only Fuseki TDB2
Hi, Is it possible to run a Fuseki server using a read-only TDB2 directory? I’d like to run a query-only SPARQL endpoint, no updates. However I get an exception at startup if the filesystem is read-only. Does Fuseki need to acquire the lock even if updates are turned off? Thank you, Jim
