Author: rvesse
Date: Mon Sep 1 07:59:08 2014
New Revision: 1621697
URL: http://svn.apache.org/r1621697
Log:
Further clarify FAQ on Impossibly Large Object exception
Modified:
jena/site/trunk/content/documentation/tdb/faqs.mdtext
Modified: jena/site/trunk/content/documentation/tdb/faqs.mdtext
URL:
http://svn.apache.org/viewvc/jena/site/trunk/content/documentation/tdb/faqs.mdtext?rev=1621697&r1=1621696&r2=1621697&view=diff
==============================================================================
--- jena/site/trunk/content/documentation/tdb/faqs.mdtext (original)
+++ jena/site/trunk/content/documentation/tdb/faqs.mdtext Mon Sep 1 07:59:08
2014
@@ -48,14 +48,20 @@ applications portable to another SPARQL
## What is the *Impossibly Large Object* exception?
The *Impossibly Large Object* exception is an exception that occurs when part
of your TDB dataset has become corrupted. It may
-only affect a small section of your dataset so may only occur intermittently
depending on your queries. A query that touches
-the entirety of the dataset will always experience this exception e.g.
+only affect a small section of your dataset so may only occur intermittently
depending on your queries. For example some queries
+may continue to function normally while other queries or queries with/without
particular features may fail. A particular query that
+fails with this error should continue to always fail unless the database is
modified.
+
+A query that touches the entirety of the dataset will always encounter this
exception and can be used to verify whether your
+database has this problem e.g.
SELECT * WHERE { { ?s ?p ?o } UNION { GRAPH ?g { ?s ?p ?o } } }
-The corruption may have happened at any time in the past and once it has
happened there
-is no way to repair it. Corrupted datasets will need to be rebuilt from the
original source data, this is why we **strongly**
-recommend you use [transactions](tdb_transactions.html) since this protects
your dataset against corruption.
+The corruption may have happened at any time in the past and once it has
happened there is no way to repair it. Corrupted datasets
+will need to be rebuilt from the original source data, this is why we
**strongly** recommend you use
+[transactions](tdb_transactions.html) since this protects your dataset against
corruption.
+
+To resolve this problem you **must** rebuild your database from the original
source data, a corrupted database **cannot** be repaired.
<a name="tdbloader-vs-tdbloader2"></a>
## What is the different between `tdbloader` and `tdbloader2`?
@@ -83,7 +89,7 @@ out. What you should set the JVM heap t
large amounts of data or use operators that may require lots of data to be
buffered in-memory e.g. `DISTINCT`, `GROUP BY`, `ORDER BY` may need a much
larger heap depending
on the overall size of your database.
-There is no hard and fast guidance we can give you on the exact number since
it depends heavily on your data and your workload. Please ask on our mailing
lists
+There is no hard and fast guidance we can give you on the exact numbers since
it depends heavily on your data and your workload. Please ask on our mailing
lists
(see our [Ask](../help_and_support/) page) and provide as much detail as
possible about your data and workload if you would like us to attempt to
provide more specific guidance.
<a name="fuseki-tdb-memory-leak"></a>
