mirror of https://gitee.com/bigwinds/arangodb
Merge branch 'devel' of https://github.com/arangodb/arangodb into devel
This commit is contained in:
Jan Steemann
commit
adca9a029d
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@ -12,29 +12,46 @@ meaning that an optimization should not modify the result of a query. A notable
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to this is that the optimizer is allowed to change the order of results for queries that
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do not explicitly specify how results should be sorted.
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!SUBSECTION Execution plans
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The `explain` command can be used to query the optimal executed plan or even all plans
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the optimizer has generated. Additionally, `explain` can reveal some more information
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about the optimizer's view of the query.
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Here's an example that shows the execution plan for a simple query, using the `explain`
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method of `ArangoStatement`:
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!SUBSECTION Inspecting plans using the explain helper
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@startDocuBlockInline AQLEXP_01_explainCreate
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@EXAMPLE_ARANGOSH_OUTPUT{AQLEXP_01_explainCreate}
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The `explain` method of `ArangoStatement` as shown in the next chapters creates very verbose output.
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You can work on the output programaticaly, or use this handsome tool that we created
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to generate a more human readable representation.
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You may use it like this: (we disable syntax highlighting here)
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@startDocuBlockInline AQLEXP_01_axplainer
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@EXAMPLE_ARANGOSH_OUTPUT{AQLEXP_01_axplainer}
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~addIgnoreCollection("test")
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db._create("test");
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for (i = 0; i < 100; ++i) { db.test.save({ value: i }); }
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db.test.ensureIndex({ type: "skiplist", fields: [ "value" ] });
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var explain = require("org/arangodb/aql/explainer").explain;
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explain("FOR i IN test FILTER i.value > 97 SORT i.value RETURN i.value", {colors:false});
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@END_EXAMPLE_ARANGOSH_OUTPUT
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@endDocuBlock AQLEXP_01_axplainer
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!SUBSECTION Execution plans in detail
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Lets have a look at the raw json output of the same execution plan
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using the `explain` method of `ArangoStatement`:
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@startDocuBlockInline AQLEXP_01_explainCreate
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@EXAMPLE_ARANGOSH_OUTPUT{AQLEXP_01_explainCreate}
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stmt = db._createStatement("FOR i IN test FILTER i.value > 97 SORT i.value RETURN i.value");
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stmt.explain();
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@END_EXAMPLE_ARANGOSH_OUTPUT
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@endDocuBlock AQLEXP_01_explainCreate
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The result details will be very verbose so they are not shown here in full. Instead,
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let's take a closer look at the results step by step.
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The as you can see, result details are very verbose so we will not shown them in full in the next
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sections. Instead, lets take a closer look at the results step by step.
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!SUBSUBSECTION Execution nodes
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@ -0,0 +1,44 @@
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arangosh> db._create(<span class="hljs-string">"test"</span>);
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[ArangoCollection <span class="hljs-number">1092291992475</span>, <span class="hljs-string">"test"</span> (type <span class="hljs-built_in">document</span>, status loaded)]
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arangosh> <span class="hljs-keyword">for</span> (i = <span class="hljs-number">0</span>; i < <span class="hljs-number">100</span>; ++i) { db.test.save({ value: i }); }
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arangosh> db.test.ensureSkiplist(<span class="hljs-string">"value"</span>);
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{
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<span class="hljs-string">"id"</span> : <span class="hljs-string">"test/1092311980955"</span>,
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<span class="hljs-string">"type"</span> : <span class="hljs-string">"skiplist"</span>,
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<span class="hljs-string">"fields"</span> : [
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<span class="hljs-string">"value"</span>
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],
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<span class="hljs-string">"unique"</span> : <span class="hljs-literal">false</span>,
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<span class="hljs-string">"sparse"</span> : <span class="hljs-literal">false</span>,
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<span class="hljs-string">"isNewlyCreated"</span> : <span class="hljs-literal">true</span>,
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<span class="hljs-string">"code"</span> : <span class="hljs-number">201</span>
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}
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arangosh> <span class="hljs-keyword">var</span> explain = <span class="hljs-built_in">require</span>(<span class="hljs-string">"org/arangodb/aql/explainer"</span>).explain;
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arangosh> explain(<span class="hljs-string">"FOR i IN test FILTER i.value > 97 SORT i.value RETURN i.value"</span>, {colors:<span class="hljs-literal">false</span>});
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Query string:
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FOR i IN test FILTER i.value > <span class="hljs-number">97</span> SORT i.value RETURN i.value
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Execution plan:
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Id NodeType Est. Comment
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<span class="hljs-number">1</span> SingletonNode <span class="hljs-number">1</span> * ROOT
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<span class="hljs-number">9</span> IndexNode <span class="hljs-number">50</span> - FOR i IN test <span class="hljs-comment">/* skiplist index scan */</span>
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<span class="hljs-number">5</span> CalculationNode <span class="hljs-number">50</span> - LET #<span class="hljs-number">3</span> = i.<span class="hljs-string">`value`</span> <span class="hljs-comment">/* attribute expression */</span> <span class="hljs-comment">/* collections used: i : test */</span>
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<span class="hljs-number">8</span> ReturnNode <span class="hljs-number">50</span> - RETURN #<span class="hljs-number">3</span>
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Indexes used:
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By Type Collection Unique Sparse Selectivity Fields Ranges
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<span class="hljs-number">9</span> skiplist test <span class="hljs-literal">false</span> <span class="hljs-literal">false</span> n/a [ <span class="hljs-string">`value`</span> ] i.<span class="hljs-string">`value`</span> > <span class="hljs-number">97</span>
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Optimization rules applied:
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Id RuleName
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<span class="hljs-number">1</span> move-calculations-up
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<span class="hljs-number">2</span> move-filters-up
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<span class="hljs-number">3</span> remove-redundant-calculations
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<span class="hljs-number">4</span> remove-unnecessary-calculations
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<span class="hljs-number">5</span> move-calculations-up-<span class="hljs-number">2</span>
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<span class="hljs-number">6</span> move-filters-up-<span class="hljs-number">2</span>
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<span class="hljs-number">7</span> use-indexes
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<span class="hljs-number">8</span> remove-filter-covered-by-index
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<span class="hljs-number">9</span> use-index-<span class="hljs-keyword">for</span>-sort
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@ -0,0 +1,75 @@
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arangosh> <span class="hljs-keyword">var</span> examples = <span class="hljs-built_in">require</span>(<span class="hljs-string">"org/arangodb/graph-examples/example-graph.js"</span>);
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arangosh> <span class="hljs-keyword">var</span> g = examples.loadGraph(<span class="hljs-string">"knows_graph"</span>);
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arangosh> db.persons.toArray()
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[
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{
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<span class="hljs-string">"name"</span> : <span class="hljs-string">"Charlie"</span>,
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<span class="hljs-string">"_id"</span> : <span class="hljs-string">"persons/charlie"</span>,
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<span class="hljs-string">"_rev"</span> : <span class="hljs-string">"1092164590491"</span>,
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<span class="hljs-string">"_key"</span> : <span class="hljs-string">"charlie"</span>
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},
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{
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<span class="hljs-string">"name"</span> : <span class="hljs-string">"Bob"</span>,
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<span class="hljs-string">"_id"</span> : <span class="hljs-string">"persons/bob"</span>,
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<span class="hljs-string">"_rev"</span> : <span class="hljs-string">"1092164328347"</span>,
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<span class="hljs-string">"_key"</span> : <span class="hljs-string">"bob"</span>
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},
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{
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<span class="hljs-string">"name"</span> : <span class="hljs-string">"Eve"</span>,
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<span class="hljs-string">"_id"</span> : <span class="hljs-string">"persons/eve"</span>,
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<span class="hljs-string">"_rev"</span> : <span class="hljs-string">"1092164983707"</span>,
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<span class="hljs-string">"_key"</span> : <span class="hljs-string">"eve"</span>
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},
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{
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<span class="hljs-string">"name"</span> : <span class="hljs-string">"Dave"</span>,
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<span class="hljs-string">"_id"</span> : <span class="hljs-string">"persons/dave"</span>,
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<span class="hljs-string">"_rev"</span> : <span class="hljs-string">"1092164787099"</span>,
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<span class="hljs-string">"_key"</span> : <span class="hljs-string">"dave"</span>
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},
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{
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<span class="hljs-string">"name"</span> : <span class="hljs-string">"Alice"</span>,
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<span class="hljs-string">"_id"</span> : <span class="hljs-string">"persons/alice"</span>,
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<span class="hljs-string">"_rev"</span> : <span class="hljs-string">"1092164131739"</span>,
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<span class="hljs-string">"_key"</span> : <span class="hljs-string">"alice"</span>
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}
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]
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arangosh> db.knows.toArray();
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[
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{
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<span class="hljs-string">"_id"</span> : <span class="hljs-string">"knows/1092165835675"</span>,
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<span class="hljs-string">"_rev"</span> : <span class="hljs-string">"1092165835675"</span>,
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<span class="hljs-string">"_key"</span> : <span class="hljs-string">"1092165835675"</span>,
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<span class="hljs-string">"_from"</span> : <span class="hljs-string">"persons/eve"</span>,
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<span class="hljs-string">"_to"</span> : <span class="hljs-string">"persons/alice"</span>
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},
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{
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<span class="hljs-string">"_id"</span> : <span class="hljs-string">"knows/1092165639067"</span>,
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<span class="hljs-string">"_rev"</span> : <span class="hljs-string">"1092165639067"</span>,
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<span class="hljs-string">"_key"</span> : <span class="hljs-string">"1092165639067"</span>,
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<span class="hljs-string">"_from"</span> : <span class="hljs-string">"persons/bob"</span>,
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<span class="hljs-string">"_to"</span> : <span class="hljs-string">"persons/dave"</span>
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},
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{
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<span class="hljs-string">"_id"</span> : <span class="hljs-string">"knows/1092165245851"</span>,
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<span class="hljs-string">"_rev"</span> : <span class="hljs-string">"1092165245851"</span>,
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<span class="hljs-string">"_key"</span> : <span class="hljs-string">"1092165245851"</span>,
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<span class="hljs-string">"_from"</span> : <span class="hljs-string">"persons/alice"</span>,
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<span class="hljs-string">"_to"</span> : <span class="hljs-string">"persons/bob"</span>
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},
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{
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<span class="hljs-string">"_id"</span> : <span class="hljs-string">"knows/1092165442459"</span>,
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<span class="hljs-string">"_rev"</span> : <span class="hljs-string">"1092165442459"</span>,
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<span class="hljs-string">"_key"</span> : <span class="hljs-string">"1092165442459"</span>,
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<span class="hljs-string">"_from"</span> : <span class="hljs-string">"persons/bob"</span>,
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<span class="hljs-string">"_to"</span> : <span class="hljs-string">"persons/charlie"</span>
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},
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{
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<span class="hljs-string">"_id"</span> : <span class="hljs-string">"knows/1092166032283"</span>,
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<span class="hljs-string">"_rev"</span> : <span class="hljs-string">"1092166032283"</span>,
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<span class="hljs-string">"_key"</span> : <span class="hljs-string">"1092166032283"</span>,
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<span class="hljs-string">"_from"</span> : <span class="hljs-string">"persons/eve"</span>,
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<span class="hljs-string">"_to"</span> : <span class="hljs-string">"persons/bob"</span>
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}
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]
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arangosh> examples.dropGraph(<span class="hljs-string">"knows_graph"</span>);
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<span class="hljs-literal">true</span>
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@ -0,0 +1,69 @@
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arangosh> <span class="hljs-keyword">var</span> examples = <span class="hljs-built_in">require</span>(<span class="hljs-string">"org/arangodb/graph-examples/example-graph.js"</span>);
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arangosh> <span class="hljs-keyword">var</span> graph = examples.loadGraph(<span class="hljs-string">"social"</span>);
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arangosh> db.female.toArray()
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[
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{
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<span class="hljs-string">"name"</span> : <span class="hljs-string">"Diana"</span>,
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<span class="hljs-string">"_id"</span> : <span class="hljs-string">"female/diana"</span>,
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<span class="hljs-string">"_rev"</span> : <span class="hljs-string">"1092171340699"</span>,
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<span class="hljs-string">"_key"</span> : <span class="hljs-string">"diana"</span>
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},
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{
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<span class="hljs-string">"name"</span> : <span class="hljs-string">"Alice"</span>,
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<span class="hljs-string">"_id"</span> : <span class="hljs-string">"female/alice"</span>,
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<span class="hljs-string">"_rev"</span> : <span class="hljs-string">"1092170619803"</span>,
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<span class="hljs-string">"_key"</span> : <span class="hljs-string">"alice"</span>
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}
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]
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arangosh> db.male.toArray()
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[
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{
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<span class="hljs-string">"name"</span> : <span class="hljs-string">"Bob"</span>,
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<span class="hljs-string">"_id"</span> : <span class="hljs-string">"male/bob"</span>,
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<span class="hljs-string">"_rev"</span> : <span class="hljs-string">"1092170947483"</span>,
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<span class="hljs-string">"_key"</span> : <span class="hljs-string">"bob"</span>
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},
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{
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<span class="hljs-string">"name"</span> : <span class="hljs-string">"Charly"</span>,
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<span class="hljs-string">"_id"</span> : <span class="hljs-string">"male/charly"</span>,
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<span class="hljs-string">"_rev"</span> : <span class="hljs-string">"1092171144091"</span>,
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<span class="hljs-string">"_key"</span> : <span class="hljs-string">"charly"</span>
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}
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]
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arangosh> db.relation.toArray()
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[
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{
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<span class="hljs-string">"type"</span> : <span class="hljs-string">"friend"</span>,
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<span class="hljs-string">"_id"</span> : <span class="hljs-string">"relation/bobAndDiana"</span>,
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<span class="hljs-string">"_rev"</span> : <span class="hljs-string">"1092172323739"</span>,
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<span class="hljs-string">"_key"</span> : <span class="hljs-string">"bobAndDiana"</span>,
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<span class="hljs-string">"_from"</span> : <span class="hljs-string">"male/bob"</span>,
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<span class="hljs-string">"_to"</span> : <span class="hljs-string">"female/diana"</span>
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},
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{
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<span class="hljs-string">"type"</span> : <span class="hljs-string">"married"</span>,
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<span class="hljs-string">"_id"</span> : <span class="hljs-string">"relation/charlyAndDiana"</span>,
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<span class="hljs-string">"_rev"</span> : <span class="hljs-string">"1092172127131"</span>,
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<span class="hljs-string">"_key"</span> : <span class="hljs-string">"charlyAndDiana"</span>,
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<span class="hljs-string">"_from"</span> : <span class="hljs-string">"male/charly"</span>,
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<span class="hljs-string">"_to"</span> : <span class="hljs-string">"female/diana"</span>
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},
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{
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<span class="hljs-string">"type"</span> : <span class="hljs-string">"friend"</span>,
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<span class="hljs-string">"_id"</span> : <span class="hljs-string">"relation/aliceAndCharly"</span>,
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<span class="hljs-string">"_rev"</span> : <span class="hljs-string">"1092171930523"</span>,
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<span class="hljs-string">"_key"</span> : <span class="hljs-string">"aliceAndCharly"</span>,
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<span class="hljs-string">"_from"</span> : <span class="hljs-string">"female/alice"</span>,
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<span class="hljs-string">"_to"</span> : <span class="hljs-string">"male/charly"</span>
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},
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{
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<span class="hljs-string">"type"</span> : <span class="hljs-string">"married"</span>,
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<span class="hljs-string">"_id"</span> : <span class="hljs-string">"relation/aliceAndBob"</span>,
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<span class="hljs-string">"_rev"</span> : <span class="hljs-string">"1092171668379"</span>,
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<span class="hljs-string">"_key"</span> : <span class="hljs-string">"aliceAndBob"</span>,
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<span class="hljs-string">"_from"</span> : <span class="hljs-string">"female/alice"</span>,
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<span class="hljs-string">"_to"</span> : <span class="hljs-string">"male/bob"</span>
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}
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]
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arangosh> examples.dropGraph(<span class="hljs-string">"social"</span>);
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<span class="hljs-literal">true</span>
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Loading…
Reference in New Issue