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JPryce-AklundhJPryce-Aklundh
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fix shortest queries
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‎modules/ROOT/pages/patterns/shortest-paths.adoc‎

Lines changed: 34 additions & 35 deletions
Original file line numberDiff line numberDiff line change
@@ -572,7 +572,7 @@ Without `CALL`, the planner does not know how many targets there are per source
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----
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PROFILE
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MATCH p = ANY SHORTEST
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(source:N {trail: ["C", "C", "A", "C", "A", "B", "B", "B", "A"]})--+
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(source:N {trail: ["C", "C", "A", "C", "A", "B", "B", "B", "A"]})--{2,}
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(target:N {trail: ["A", "B", "C", "A", "B", "C", "A", "B", "C"]})
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RETURN length(p) AS pathLength
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----
@@ -596,24 +596,24 @@ It, therefore, must exhaust all possible target nodes before determining the sho
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+-----------------------------------+----+----------------------------------------------------------------------+----------------+-------+---------+----------------+------------------------+-----------+---------------------+
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| Operator | Id | Details | Estimated Rows | Rows | DB Hits | Memory (Bytes) | Page Cache Hits/Misses | Time (ms) | Pipeline |
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+-----------------------------------+----+----------------------------------------------------------------------+----------------+-------+---------+----------------+------------------------+-----------+---------------------+
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| +ProduceResults | 0 | `length(p)` | 19612941 | 1 | 0 | 0 | 0/0 | 0.027 | |
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| +ProduceResults | 0 | pathLength | 19612941 | 1 | 0 | 0 | 0/0 | 0.228 | |
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| | +----+----------------------------------------------------------------------+----------------+-------+---------+----------------+------------------------+-----------+ |
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| +Projection | 1 | length((source)-[anon_7*]-(target)) AS `length(p)` | 19612941 | 1 | 17 | | 9/0 | 0.036 | |
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| +Projection | 1 | length((source)-[anon_7*]-(target)) AS pathLength | 19612941 | 1 | 17 | | 9/0 | 1.405 | |
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| | +----+----------------------------------------------------------------------+----------------+-------+---------+----------------+------------------------+-----------+ |
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| +StatefulShortestPath(All, Trail) | 2 | SHORTEST 1 (source) ((`anon_3`)-[`anon_4`]-(`anon_5`)){1, } (target) | 19612941 | 1 | 354292 | 64720328 | 85358/0 | 139.138 | In Pipeline 1 |
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| +StatefulShortestPath(All, Trail) | 2 | SHORTEST 1 (source) ((`anon_3`)-[`anon_4`]-(`anon_5`)){2, } (target) | 19612941 | 1 | 354300 | 65608340 | 85662/0 | 290.001 | In Pipeline 1 |
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| | | | expanding from: source | | | | | | | |
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| | | | inlined predicates: target.trail = $autolist_1 | | | | | | | |
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| | | | target:N | | | | | | | |
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| | +----+----------------------------------------------------------------------+----------------+-------+---------+----------------+------------------------+-----------+---------------------+
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| +Filter | 3 | source.trail = $autolist_0 | 4429 | 1 | 177146 | | | | |
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| | +----+----------------------------------------------------------------------+----------------+-------+---------+----------------+ | | |
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| +NodeByLabelScan | 4 | source:N | 88573 | 88573 | 88574 | 376 | 2128/0 | 42.628 | Fused in Pipeline 0 |
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| +NodeByLabelScan | 4 | source:N | 88573 | 88573 | 88574 | 376 | 1853/0 | 56.193 | Fused in Pipeline 0 |
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+-----------------------------------+----+----------------------------------------------------------------------+----------------+-------+---------+----------------+------------------------+-----------+---------------------+
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Total database accesses: 620029, total allocated memory: 64720664
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Total database accesses: 620037, total allocated memory: 65608676
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1 row
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ready to start consuming query after 59 ms, results consumed after another 183 ms
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ready to start consuming query after 83 ms, results consumed after another 351 ms
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----
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However, since each `trail` property is unique, rewriting the query to use a `CALL` subquery yields a more efficient plan.
@@ -626,43 +626,43 @@ PROFILE
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MATCH (start:N {trail: ["C", "C", "A", "C", "A", "B", "B", "B", "A"]}),
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(end:N {trail: ["A", "B", "C", "A", "B", "C", "A", "B", "C"]})
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CALL (start, end) {
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MATCH p = ANY SHORTEST (start)--+(end)
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MATCH p = ANY SHORTEST (start)--{2,}(end)
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RETURN p
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}
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RETURN length(p) AS pathLength
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----
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The result is a significantly faster query (down from 59 to 9 milliseconds):
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The result is a less resource intensive query:
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.Query Plan
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[source, role="queryplan"]
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----
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+------------------------------------+----+----------------------------------------------------------------+----------------+-------+---------+----------------+------------------------+-----------+---------------------+
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| Operator | Id | Details | Estimated Rows | Rows | DB Hits | Memory (Bytes) | Page Cache Hits/Misses | Time (ms) | Pipeline |
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+------------------------------------+----+----------------------------------------------------------------+----------------+-------+---------+----------------+------------------------+-----------+---------------------+
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| +ProduceResults | 0 | `length(p)` | 19612941 | 1 | 0 | 0 | 0/0 | 0.019 | |
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| | +----+----------------------------------------------------------------+----------------+-------+---------+----------------+------------------------+-----------+ |
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| +Projection | 1 | length(p) AS `length(p)` | 19612941 | 1 | 0 | | 0/0 | 0.007 | |
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| | +----+----------------------------------------------------------------+----------------+-------+---------+----------------+------------------------+-----------+ |
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| +Projection | 2 | (start)-[anon_14*]-(end) AS p | 19612941 | 1 | 17 | | 9/0 | 0.073 | |
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| | +----+----------------------------------------------------------------+----------------+-------+---------+----------------+------------------------+-----------+ |
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| +StatefulShortestPath(Into, Trail) | 3 | ANY 1 (start) ((`anon_10`)-[`anon_11`]-(`anon_12`)){1, } (end) | 19612941 | 1 | 1936 | 990280 | 205/0 | 1.135 | In Pipeline 3 |
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| | +----+----------------------------------------------------------------+----------------+-------+---------+----------------+------------------------+-----------+---------------------+
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| +CartesianProduct | 4 | | 19612941 | 1 | 0 | 9040 | | 0.131 | In Pipeline 2 |
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| |\ +----+----------------------------------------------------------------+----------------+-------+---------+----------------+------------------------+-----------+---------------------+
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| | +Filter | 5 | end.trail = $autolist_1 | 22143 | 1 | 177146 | | | | |
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| | | +----+----------------------------------------------------------------+----------------+-------+---------+----------------+ | | |
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| | +NodeByLabelScan | 6 | end:N | 442865 | 88573 | 88574 | 392 | 2128/0 | 29.822 | Fused in Pipeline 1 |
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| | +----+----------------------------------------------------------------+----------------+-------+---------+----------------+------------------------+-----------+---------------------+
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| +Filter | 7 | start.trail = $autolist_0 | 4429 | 1 | 177146 | | | | |
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| | +----+----------------------------------------------------------------+----------------+-------+---------+----------------+ | | |
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| +NodeByLabelScan | 8 | start:N | 88573 | 88573 | 88574 | 376 | 2128/0 | 40.743 | Fused in Pipeline 0 |
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+------------------------------------+----+----------------------------------------------------------------+----------------+-------+---------+----------------+------------------------+-----------+---------------------+
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Total database accesses: 533393, total allocated memory: 999592
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+------------------------------------+----+------------------------------------------------------------------+----------------+-------+---------+----------------+------------------------+-----------+---------------------+
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| Operator | Id | Details | Estimated Rows | Rows | DB Hits | Memory (Bytes) | Page Cache Hits/Misses | Time (ms) | Pipeline |
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+------------------------------------+----+------------------------------------------------------------------+----------------+-------+---------+----------------+------------------------+-----------+---------------------+
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| +ProduceResults | 0 | pathLength | 19612941 | 1 | 0 | 0 | 0/0 | 0.116 | |
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| | +----+------------------------------------------------------------------+----------------+-------+---------+----------------+------------------------+-----------+ |
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| +Projection | 1 | length(p) AS pathLength | 19612941 | 1 | 0 | | 0/0 | 0.012 | |
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| | +----+------------------------------------------------------------------+----------------+-------+---------+----------------+------------------------+-----------+ |
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| +Projection | 2 | (start)-[anon_7*]-(end) AS p | 19612941 | 1 | 17 | | 9/0 | 0.122 | |
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| | +----+------------------------------------------------------------------+----------------+-------+---------+----------------+------------------------+-----------+ |
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| +StatefulShortestPath(Into, Trail) | 3 | SHORTEST 1 (start) ((`anon_3`)-[`anon_4`]-(`anon_5`)){2, } (end) | 19612941 | 1 | 1952 | 1337600 | 209/0 | 2.786 | In Pipeline 3 |
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| | +----+------------------------------------------------------------------+----------------+-------+---------+----------------+------------------------+-----------+---------------------+
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| +CartesianProduct | 4 | | 19612941 | 1 | 0 | 9040 | | 0.053 | In Pipeline 2 |
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| |\ +----+------------------------------------------------------------------+----------------+-------+---------+----------------+------------------------+-----------+---------------------+
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| | +Filter | 5 | end.trail = $autolist_1 | 22143 | 1 | 177146 | | | | |
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| | | +----+------------------------------------------------------------------+----------------+-------+---------+----------------+ | | |
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| | +NodeByLabelScan | 6 | end:N | 442865 | 88573 | 88574 | 392 | 1853/0 | 37.853 | Fused in Pipeline 1 |
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| | +----+------------------------------------------------------------------+----------------+-------+---------+----------------+------------------------+-----------+---------------------+
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| +Filter | 7 | start.trail = $autolist_0 | 4429 | 1 | 177146 | | | | |
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| | +----+------------------------------------------------------------------+----------------+-------+---------+----------------+ | | |
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| +NodeByLabelScan | 8 | start:N | 88573 | 88573 | 88574 | 376 | 1853/0 | 67.672 | Fused in Pipeline 0 |
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+------------------------------------+----+------------------------------------------------------------------+----------------+-------+---------+----------------+------------------------+-----------+---------------------+
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Total database accesses: 533409, total allocated memory: 1346912
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1 row
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ready to start consuming query after 9 ms, results consumed after another 73 ms
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ready to start consuming query after 78 ms, results consumed after another 120 ms
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----
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======
@@ -845,8 +845,7 @@ Or, when the estimated cardinality of the source and target nodes in a shortest
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* Selector is one of: `SHORTEST 1`, `ANY`, `ANY SHORTEST`, `ALL SHORTEST`, `SHORTEST GROUP`, or `SHORTEST 1 GROUP`.
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* There is only one relationship pattern.
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* If the pattern is a xref:patterns/variable-length-patterns.adoc#quantified-path-patterns[quantified path pattern] in the form of `\(()-[]-())`, or is a xref:patterns/variable-length-patterns.adoc#quantified-relationships[quantified-relationship], and it uses a filter that can be applied directly to the relationship.
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* If the pattern is a quantified path pattern or a quantified relationship and the relationship pattern is directed, the lower bound of the xref:patterns/reference.adoc#quantifiers[quantifier] is 0 or 1.
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If the relationship pattern is directed, the lower bound is 0.
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* If the pattern is a quantified path pattern or a quantified relationship, the lower bound of the xref:patterns/reference.adoc#quantifiers[quantifier] is 0 or 1.
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* In the case of a quantified path pattern, there are no node variables declared inside the quantified path pattern that are referenced elsewhere.
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| `StatefulShortestPath(Into)`

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