Function: Advanced DECREMENT operation

Enterprise Edition

Goal: Perform the Advanced DECREMENT operation where Eventing interacts with the Data service.

This function advancedDecrementOp merely demonstrates the Advanced DECREMENT operation.
Requires Eventing Storage (or metadata collection) and a "source" collection.
Needs a Binding of type "bucket alias" (as documented in the Scriptlet).
Will operate on any mutation and count down (decrement) the mutations subject to DCP dedup.
For more information refer to Advanced DECREMENT operation in the detailed documentation.

advancedDecrementOp
Input Data/Mutation
Output Data
Output Log

// To run configure the settings for this Function, advancedDecrementOp, as follows:
//
// Version 7.1+
//   "Function Scope"
//     *.* (or try bulk.data if non-privileged)
// Version 7.0+
//   "Listen to Location"
//     bulk.data.source
//   "Eventing Storage"
//     rr100.eventing.metadata
//   Binding(s)
//    1. "binding type", "alias name...", "bucket.scope.collection", "Access"
//       "bucket alias", "src_col",       "bulk.data.source",        "read and write"
//
// Version 6.6.1
//   "Source Bucket"
//     source
//   "MetaData Bucket"
//     metadata
//   Binding(s)
//    1. "binding type", "alias name...", "bucket",     "Access"
//       "bucket alias", "src_col",       "source",     "read and write"

function OnUpdate(doc, meta) {
    if (!meta.id.startsWith("dec:")) return;
    // log('input meta', meta);
    // log('input doc ', doc);

    // if doc.count doesn't exist it will be created
    var ctr_meta = {"id": "my_atomic_counter:1" };
    var result = couchbase.decrement(src_col,ctr_meta);
    if (result.success) {
        log('success adv. decrement: result',result);
    } else {
        log('failure adv. decrement: id',ctr_meta.id,'result',result);
    }
}

UPSERT INTO `bulk`.`data`.`source` (KEY,VALUE)
  VALUES ( "dec:1",  {"somekey":"someValue"} ),
  VALUES ( "dec:2",  {"somekey":"someValue"} ),
  VALUES ( "dec:3",  {"somekey":"someValue"} ),
  VALUES ( "dec:4",  {"somekey":"someValue"} ),
  VALUES ( "dec:5",  {"somekey":"someValue"} ),
  VALUES ( "dec:6",  {"somekey":"someValue"} ),
  VALUES ( "dec:7",  {"somekey":"someValue"} ),
  VALUES ( "dec:8",  {"somekey":"someValue"} ),
  VALUES ( "dec:9",  {"somekey":"someValue"} ),
  VALUES ( "dec:10", {"somekey":"someValue"} );

We insert ten (10) documents and count the mutations via decrementing

KEY: my_atomic_counter:1

{
  "count": -10
}

2021-01-08T12:30:59.910-08:00 [INFO] "success adv. increment: result"
{"doc":{"count":-1},"meta":{"id":"my_atomic_counter:1","cas":"1610137859908960256"},"success":true}

2021-01-08T12:30:59.910-08:00 [INFO] "success adv. increment: result"
{"doc":{"count":-2},"meta":{"id":"my_atomic_counter:1","cas":"1610137859909222400"},"success":true}

2021-01-08T12:30:59.911-08:00 [INFO] "success adv. increment: result"
{"doc":{"count":-3},"meta":{"id":"my_atomic_counter:1","cas":"1610137859911385088"},"success":true}

2021-01-08T12:30:59.931-08:00 [INFO] "success adv. increment: result"
{"doc":{"count":-4},"meta":{"id":"my_atomic_counter:1","cas":"1610137859929997312"},"success":true}

2021-01-08T12:30:59.931-08:00 [INFO] "success adv. increment: result"
{"doc":{"count":-5},"meta":{"id":"my_atomic_counter:1","cas":"1610137859930193920"},"success":true}

2021-01-08T12:30:59.932-08:00 [INFO] "success adv. increment: result"
{"doc":{"count":-6},"meta":{"id":"my_atomic_counter:1","cas":"1610137859932160000"},"success":true}

2021-01-08T12:30:59.932-08:00 [INFO] "success adv. increment: result"
{"doc":{"count":-7},"meta":{"id":"my_atomic_counter:1","cas":"1610137859932356608"},"success":true}

2021-01-08T12:30:59.948-08:00 [INFO] "success adv. increment: result"
{"doc":{"count":-8},"meta":{"id":"my_atomic_counter:1","cas":"1610137859946381312"},"success":true}

2021-01-08T12:30:59.948-08:00 [INFO] "success adv. increment: result"
{"doc":{"count":-9},"meta":{"id":"my_atomic_counter:1","cas":"1610137859946708992"},"success":true}

2021-01-08T12:30:59.948-08:00 [INFO] "success adv. increment: result"
{"doc":{"count":-10},"meta":{"id":"my_atomic_counter:1","cas":"1610137859948412928"},"success":true}