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Error creating index on RDF model

681909Apr 14 2010 — edited Apr 16 2010
I am running the create index as shown in 1.9 of the Semantic Developers Guide. I have 4 Oracle semantic models. All of our access is via sparql, with most of the 'WHERE' logic focused on the object part of the triples. We do a lot of querying on specific value and a lot of REGEX, primarily on the object values. So, it seems to me to be a good idea to build an index on the object part of the triples. However, this:

create index POINT_OBJ_IDX on POINT (TO_CHAR(TRIPLE.GET_OBJECT())) throws this error:

ORA-22835: Buffer too small for CLOB to CHAR or BLOB to RAW conversion (actual:
4223, maximum: 4000)

Of the 4 models, 2 the index create works fine and the other 2 throw the error.

Is there any way I can query the model or inspect using some other method that will show me which triple(s) are causing this error when building the index?

Comments

Greybird-Oracle
Answer

Hi Keith,

Since you have read the other information about this problem, I assume you know that upgrading to JE 6 (use the most recent release of course) is the only sure solution, but setting CLEANER_ADJUST_UTILIZATION to false will work for some applications. If it is working for you, that's great, but please plan to upgrade.

The reason that EVICT_LN would bring out this problem is that, after the LN (data record) is evicted, the Btree no longer contains its size. Then when you delete the record, JE has to guess the size using an average. If the LN were still in cache, the size would be known at the time it is deleted. In JE 6 and above, the size is stored in the Btree even after the LN is evicted, which solves the problem.

--mark

Marked as Answer by keithwall · Sep 27 2020
keithwall

Thanks for the swift reply.  That completely answers my question.

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Locked on May 14 2010
Added on Apr 14 2010
#database-key-features, #rdf-graph-property-graph
8 comments
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