There are 4 methods of executing algorithm, only one can be used at one time:

See chapter Task of the UQL manual for task operations.

Task Writeback

Using write() parameter to write the algorithm results and statistics back to specified location(s), which includes file writeback (file), property writeback (db) and statistics writeback (stats). It is not supported to writeback to file and property at the same time; however, the statistics (if has) will be written back to the task automatically.

1. File Writeback

Write the algorithm results back to one or multiple files, filename(s) are required. There is no table header contained in the file(s), English comma is used to separate the data in one row. At the same time, automatically write the algorithm statistics (if has) back to algorithm task.

Syntax: Wrap file object in the parameter write()

algo(<>).params(<>).write({ 
  file:{
    filename: "<filename>"
  }
})

algo(<>).params(<>).write({ 
  file:{
    filename_<result1>: "<filename>", 
    filename_<result2>: "<filename>", 
    ...
  }
})

In regard to the filename extension, it is suggested to use .csv or .txt, or to ignore it.

Example: Run Triangle Counting algorithm in the graph and write the results back to file, the filename is count

algo(triangle_counting).params().write({
  file:{
    filename: "count.csv"
  }
})

Results displayed in Ultipa Manager: View (File download link and algorithm statistics are both displayed under the Result column of task information)

Example: Run K-Hop Whole Graph algorithm in the graph and write the results back to files, the filenames are khop_ids and khop_num

algo(khop_all).params().write({
  file:{
    filename_ids: "khop_ids.csv",
    filename_num: "khop_num.csv" 
  }
})

Results displayed in Ultipa Manager: View (File download links are displayed under the Result column of task information, K-Hop Whole Graph algorithm does not have statistics)

2. Property Writeback

Write the algorithm results back to one or multiple properties, property name is required. The property to be written back can be node property or edge property. At the same time, automatically write the algorithm statistics (if has) back to algorithm task.

Property writeback is a whole-data operation, which means to writeback to all nodes or edges in the current graphset, so that schema need not be specified when the name of property is given. For any schema, if it does not contain the property to be written back, the property would be created automatically; if the property does exist but its data type is not the same with the data to be written back, the writeback would fail for that schema. For nodes or edges that have calculation results, the results are to be written back to their properties; for nodes or edges have no result (such as when it is not whole-data operation), results of 0, null or other empty value would be written back according to the data type.

Syntax: Wrap db object in parameter write()

algo(<>).params(<>).write({
  db:{
    property: "<property>"
  }
})

Example: Run Closeness Centrality algorithm in the graph and write the results back to node property centrality

algo(closeness_centrality).params().write({
  db:{
    property: "centrality"
  }
})

Results displayed in Ultipa Manager: View (Algorithm results are written back to the property centrality of nodes; Closeness Centrality algorithm doesn't have statistics so the Result column of task information is blank)

Example: Run Label Propagation algorithm in the graph and keep two labels for each node the maximum, write the results back to node property label_1, probability_1, label_2 and probability_2

algo(lpa).params({k:2}).write({
  db:{
    property: "label"
  }
})

Results displayed in Ultipa Manager: View (Algorithm results are written back to the property label_1, probability_1, label_2 and probability_2 of nodes, algorithm statistics is displayed under the Result column of task information)

When each node (or edge) has multiple results after some algorithm executes, still only one property name <property> needs to be specified, the system will automatically writes all results back to different properties.

Like the Label Propagation algorithm in the above example, only property name label is specified for 'label', the property name of its 'probability' is pre-defined and not modifiable, and a serial number is added to each property by the system automatically when writing back.

3. Stats Writeback

Algorithm statistics is recorded in task information if the algorithm has statistics. Statistics is recorded automatically when executing in the way of file writeback or property writeback; executing statistics writeback is to record algorithm statistics alone.

Syntax: Use parameter write() directly

algo(<>).params(<>).write()

Example: Run Degree algorithm in the graph and write the statistics total_degree and average_degree back to the task

algo(degree).params().write()

Results displayed in Ultipa Manager: View (Algorithm statistics are written back to the Result column of task information)

Direct Return

Syntax: Define alias and assemble with return clause

// Return algorithm results and statistics in real time
algo(<>).params(<>) as <alias1>, <alias2>
return <alias0>, <alias1>
  
// Return algorithm results in real time
algo(<>).params(<>) as <alias>
return <alias>

When defining aliases for algorithm statement, the order matters. The one written first refers to algorithm results, and the one after is algorithm statistics. User needs to follow this rule regulated by the system. If algorithm does not have statistics, only one alias can be defined for the algorithm statement.

Certain column of algorithm results or statistics can be referenced in the return clause. Regarding to the definition and reference of alias, please see the chapter Query of the UQL documentation.

Example: Run Degree algorithm in the graph and return the results (define as alias a1) and the statistics (define as alias a2) directly

algo(degree).params() as a1, a2 
return a1, a2

Results displayed in Ultipa Manager: a1, a2

Example: Modify the above example, return algorithm results and statistics in separated columns

algo(degree).params() as a1, a2
return a1._uuid, a1.degree, a2.total_degree, a2.average_degree

Results displayed in Ultipa Manager: a1._uuid, a1.degree, a2.total_degree, a2.average_degree

For the definition, usage and reference of alias, please read the Query chapter of the UQL documentation.

Stream Return

Syntax: Use parameter stream()

// Execute the algorithm and define the results as alias named '<alias>', in this way the algorithm results can be returned or used as the input of subsequent UQL statements 
algo(<>).params(<>).stream() as <alias>
...

Example: Run Closeness Centrality algorithm in the graph and return the results as real-time data stream (define as alias cc)

algo(closeness_centrality).params().stream() as cc
return cc

Results displayed in Ultipa Manager: cc

Example: Modify the above example, return UUID of nodes whose closeness centrality is greater than 0.5

algo(closeness_centrality).params().stream() as cc
where cc.centrality > 0.5
return cc._uuid

Results displayed in Ultipa Manager: cc._uuid

Data stream generated by algorithm statement can be used in the subsequent query commands, but cannot be used to insert, update or delete metadata.

Stats Return

Syntax: Use parameter stats()

// Execute the algorithm and define the statistics as alias named '<alias>', in this way the algorithm statistics can be returned or used as the input of subsequent UQL statements 
algo(<>).params(<>).stats() as <alias>
...

Example: Run Degree algorithm in the graph and return the statistics (define as alias sta) in real time

algo(degree).params().stats() as sta
return sta

Results displayed in Ultipa Manager: sta

Example: Modify the above example, return algorithm statistics in separated columns

algo(degree).params().stats() as sta
return sta.total_degree, sta.average_degree

Results displayed in Ultipa Manager: sta.total_degree，sta.average_degree