Hi Ivan,
On Wed, Nov 2, 2016 at 12:32 PM, Ivan Mikhailov <imikhai...@openlinksw.com>
wrote:
>
> How do you know that FILTER (STRLEN(?literal) = 8) is executed before
> SUBSTR(?literal, 8, 1) ?
FILTER is placed before SUBSTR in the WHERE clause. SPARQL optimizer may
(incorrectly) switch that order.
> What's the full text of the query?
The original query is at https://github.com/jindrichmynarz/vvz-to-rdf/blob/
f8d421002eef19359ffd89b0d209b47e87b2ee0e/sparql/invalid_ico_revalidate.ru.
Virtuoso translates SPARQL to SQL and uses all allowed term rewritings
> and other tricks trying to get highest possible speed. As a side effect,
> the order of execution may be non-linear. So the simplest step of
> debugging is an additional test: what if
> SUBSTR(?literal, 8, 1)
> is replaced with
> IF (STRLEN(?literal) = 8), SUBSTR(?literal, 8, 1), "some fallback
> value")
> ?
>
I tried that (with fallback = 1) only to stumble upon another error:
Virtuoso 22023 Error SR553: Literal of type xsd:integer can not be created
from SQL value of type rdf (246): SR341: Invalid integer value converting
'A'
To my knowledge, there's no literal "A" to be casted to an integer.
- Jindřich
--
Jindřich Mynarz
http://mynarz.net/#jindrich
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