Hi Tom, On Thu, Nov 5, 2015 at 6:12 PM, Tom Johnson <t...@dp.la> wrote: > > We can confirm that upgrading to PSQL 9.2+ (we are using 9.4) has > significant performance benefits on LDP requests. GET requests that had > been taking between 10 and 50 seconds are now observed at around 1/10 of a > second, with much of that time apparently spent on the Marmotta side rather > than in PSQL. >
Definitely PostgreSQL has brought quite some improvements in 9.4 that we strongly recommend it for Marmotta. After the upgrade, we saw vastly improved performance for a time, but found > that under a certain load similar query planning problems resurfaced. > Perhaps oddly, we were able to stem this by creating a new index on the > triples table, with a different field order from the existing four-column > index. The new index (on `spoc` rather than `cspo`) is used more readily in > the generic plan, and we've not seen slow queries (> 200ms) logged on LDP > requests since introducing it. > Those are really good news! Probably there is still room to improve the current implementation. But also take into account that currently the LDP module uses Sesame-based persistence with KiWi. Following the experience on providing a SQL native SPARQL evaluation strategy, we could try something similar for improving even more the LDP performance. But I'd prefer to keep that plan aside if possible. Cheers, -- Sergio Fernández Partner Technology Manager Redlink GmbH m: +43 6602747925 e: sergio.fernan...@redlink.co w: http://redlink.co
