[
https://issues.apache.org/jira/browse/JENA-384?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17489435#comment-17489435
]
Andy Seaborne commented on JENA-384:
------------------------------------
The new (2022) SPARQL APIs introduce \{{substitution}} to replace initial
bindings. \{{substitution}} is syntactic replacement of variables by values
(points 1 & 2 above) and happens before query execution planning. It also
applies uniformly to local and remote whereas initial binding is a local-only
and fragile mechanism.
> Interaction of optimization (TransformFilterEquality) and initial binding
> -------------------------------------------------------------------------
>
> Key: JENA-384
> URL: https://issues.apache.org/jira/browse/JENA-384
> Project: Apache Jena
> Issue Type: Bug
> Components: ARQ, Optimizer
> Affects Versions: ARQ 2.9.4, Jena 2.10.0
> Reporter: Andy Seaborne
> Priority: Major
> Attachments: ReportSubstitueOptimize.java
>
>
> substitution is normally done after optimization so that it preserves the
> semantics in case of complex optional situations.
> The equality filter optimization eliminates code that can't generate a
> solution (the variable is unbound in the subexpression)
> This can be unexpected but it's neither clearly right or clearly wrong. The
> semantics of initial binding need clarifying;
> either
> pure substitution semantics, with the substitution applied before
> optimization
> or
> VALUES semantics (join with a data table) in which case elimination of
> redundant pattern matching is correct.
> In the example, it's only an issue with URIs (reason?) but the general point
> remains.
--
This message was sent by Atlassian Jira
(v8.20.1#820001)
