NetSuite SuiteScript Map Reduce Script Learning Note学习笔记

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Stage 1. getInputData

• returns an object that can be transformed into a list of key/value pairs
• hard limit: 10,000 usage units, SSS_USAGE_LIMIT_EXCEEDED
• out data to map if have or to shuffle otherwise
• function: getInputData(inputContext)

Stage 2. map

• invokes one time for each key/value pair
• can write output data, in the form of new key/value pairs.
• if has reduce, output data to the shuffle and then the reduce stage
• if no reduce, sent to the summarize stage
• 1,000 usage units (the same as mass update scripts)
• function: map(mapContext)

Stage 3. shuffle

• the system sorts through any key/value pairs that were sent to the reduce stage
• to form a new set of key/value pairs, where each key is unique and each value is an array.
• function: no need write function

Stage 4. reduce

• invoked one time for each key/value pair that was provided by the shuffle stage.
• can write data as key/value pairs that are sent to the summarize stage.
• 5,000 usage units
• function: reduce(reduceContext)

Stage 5. summarize

• can retrieve and log statistics about the script's work
• can also take actions with data sent by the reduce stage
• 10,000 usage units
• function: summarize(summaryContext)

Notes

• may omit either the map or reduce function
• can also omit the summarize function
• The system supplements your logic
• The system provides robust context objects
• multiple jobs are used to execute one script
• serial stages: one getInputData job, one shuffle job and one summarize job
• parallel stages: multiple map and reduce jobs that work independently

Governance

Soft limit: yielding

• after the completion of each map or reduce function invocation
• never interrupts a function invocation
• occurring reasons
  • The time limit specified by the Yield After Minutes field on the script deployment record. (3-60)
  • The governance limit of 10,000 usage units per map or reduce job.

Hard Limits on Total Persisted Data

• a map/reduce script cannot exceed 200MB at any one time
• STORAGE_SIZE_EXCEEDED error

Hard Limits on Function Invocations

• getInputData: 10,000 usage units
• map: 1,000 usage units (the same as mass update scripts)
• reduce: 5,000 usage units
• summarize: 10,000 usage units
• SSS_USAGE_LIMIT_EXCEEDED error

Best Practices

Writing Efficient Map and Reduce Functions

• map better only handle one record

Passing Search Data to the getInputData Stage

• return either a search object or a saved search reference
• return the results gets greater risk for search timeout

Minimizing the Risk of Data Duplication

• Add Logic for Handling Restarts
  • context.isRestarted
• Leave Buffer Size Set to 1