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Clarifications about the use of ToList in algebra expressions #140

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Mar 7, 2024
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Clarifications about the use of ToList in algebra expressions #140

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b1c5df0
fixes the 'Pattern involving a subquery' example, as per #136
hartig Feb 22, 2024
ea40eea
clarifies that the ToList operator needs to be applied before applyin…
hartig Feb 22, 2024
7856573
Maintain indents
hartig Feb 22, 2024
2a9df90
Fixes typo
hartig Feb 22, 2024
9687c06
Small edit.
hartig Feb 23, 2024
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31 changes: 21 additions & 10 deletions spec/index.html
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Original file line number Diff line number Diff line change
Expand Up @@ -8840,8 +8840,11 @@ <h4>Examples of Mapped Graph Patterns</h4>
Join(<br>
&nbsp;&nbsp; BGP(?s :p ?o) ,<br>
&nbsp;&nbsp; ToMultiSet(<br>
&nbsp;&nbsp;&nbsp;&nbsp; Distinct(Project(BGP(?o ?p ?z), {?o})) )<br>
&nbsp;&nbsp; )
&nbsp;&nbsp;&nbsp;&nbsp; Distinct( <br>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; Project( ToList(BGP(?o ?p ?z)), {?o} ) <br>
&nbsp;&nbsp;&nbsp;&nbsp; ) <br>
&nbsp;&nbsp; ) <br>
)
</div>
</div>
</section>
Expand Down Expand Up @@ -8994,8 +8997,22 @@ <h5>SELECT Expressions</h5>
</section>
<section id="convertSolMod">
<h4>Converting Solution Modifiers</h4>
<p>Solutions modifiers apply to the processing of a SPARQL query after pattern matching.
The solution modifiers are applied to a query in the following order:</p>
<p>Solution modifiers apply to the processing of a SPARQL query after pattern matching.</p>
<p>Since the solution modifiers operate on sequences
of solution mappings, the query result produced up to this
point is first turned from a multiset of solution mappings
into such a sequence. While there is no implied ordering to
this sequence, and duplicates need not be adjacent, the sequence
is identical to the multiset in terms of the elements that it
contains, and their multiplicities. To apply this conversion
from a multiset into a sequence, the algorithm for capturing
the solution modifiers in the algebra expression begins with
the following step, where <var>Pattern</var> is the algebra
expression produced by the algorithm in the previous section.</p>
<blockquote>
<p>Let M := ToList(<var>Pattern</var>)</p>
</blockquote>
<p>Now, the solution modifiers are applied in the following order:</p>
<ul>
<li>Order by</li>
<li>Projection</li>
Expand All @@ -9004,12 +9021,6 @@ <h4>Converting Solution Modifiers</h4>
<li>Offset</li>
<li>Limit</li>
</ul>
<p>Step: ToList</p>
<p>ToList turns a multiset into a sequence with the same elements and multiplicities. There is
no implied ordering to the sequence; duplicates need not be adjacent.</p>
<blockquote>
<p>Let M := ToList(Pattern)</p>
</blockquote>
<section id="sparqlOrderBy">
<h5>ORDER BY</h5>
<p>If the query string has an ORDER BY clause</p>
Expand Down
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