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Change ExpandUniquenessFilter to EdgeUniquenessFilter in planning docs

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Reviewers: teon.banek

Reviewed By: teon.banek

Differential Revision: https://phabricator.memgraph.io/D2069
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Marin Tomic 2019-05-17 16:34:44 +02:00
parent 4f4837392e
commit 4e927a52e1
1 changed files with 9 additions and 9 deletions
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18
docs/dev/query/planning.md
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@ -170,10 +170,10 @@ destination node is stored in `m`.
Matching multiple relationships proceeds similarly, by repeating the same Matching multiple relationships proceeds similarly, by repeating the same
steps. The only difference is that we need to ensure different edges in the steps. The only difference is that we need to ensure different edges in the
search pattern, map to different edges in the graph. This means that after search pattern, map to different edges in the graph. This means that after each
each `Expand` operator, we need to generate an `ExpandUniquenessFilter`. We `Expand` operator, we need to generate an `EdgeUniquenessFilter`. We provide
provide this operator with a list of symbols for the previously matched edges this operator with a list of symbols for the previously matched edges and the
and the symbol for the current edge. symbol for the current edge.
For example. For example.
@ -187,9 +187,9 @@ Then we look at each triplet in order and perform the described steps. This
way, we would generate: way, we would generate:
ScanAll (n) > Expand (n, r1, m) > Expand (m, r2, l) > ScanAll (n) > Expand (n, r1, m) > Expand (m, r2, l) >
ExpandUniquenessFilter ([r1], r2) EdgeUniquenessFilter ([r1], r2)
Note that we don't need to make `ExpandUniquenessFilter` after the first Note that we don't need to make `EdgeUniquenessFilter` after the first
`Expand`, since there are no edges to compare to. This filtering needs to work `Expand`, since there are no edges to compare to. This filtering needs to work
across multiple pattern, but inside a *single* `MATCH` clause. across multiple pattern, but inside a *single* `MATCH` clause.
@ -200,7 +200,7 @@ Let's take a look at the following.
We would also generate the exact same operators. We would also generate the exact same operators.
ScanAll (n) > Expand (n, r1, m) > Expand (m, r2, l) > ScanAll (n) > Expand (n, r1, m) > Expand (m, r2, l) >
ExpandUniquenessFilter ([r1], r2) EdgeUniquenessFilter ([r1], r2)
On the other hand, On the other hand,
@ -210,7 +210,7 @@ would reset the uniqueness filtering at the start of the second match. This
would mean that we output the following: would mean that we output the following:
ScanAll (n) > Expand (n, r1, m) > Expand (m, r2, l) > Expand (l, r3, i) > ScanAll (n) > Expand (n, r1, m) > Expand (m, r2, l) > Expand (l, r3, i) >
ExpandUniquenessFilter ([r2], r3) EdgeUniquenessFilter ([r2], r3)
There is a difference in how we handle edge uniqueness compared to Neo4j. There is a difference in how we handle edge uniqueness compared to Neo4j.
Neo4j does not allow searching for a single edge multiple times, but we've Neo4j does not allow searching for a single edge multiple times, but we've
@ -226,7 +226,7 @@ generate this plan.
ScanAll (n) > Expand (n, r, m) > Expand (m, r, l) ScanAll (n) > Expand (n, r, m) > Expand (m, r, l)
We do not put an `ExpandUniquenessFilter` operator between 2 `Expand` We do not put an `EdgeUniquenessFilter` operator between 2 `Expand`
operators and we tell the 2nd `Expand` that it is an edge cycle. This, 2nd operators and we tell the 2nd `Expand` that it is an edge cycle. This, 2nd
`Expand` will ensure we have matched both the same edges. `Expand` will ensure we have matched both the same edges.