March 16, 2025
Goal: Perform the Advanced DECREMENT operation where Eventing interacts with the Data service.
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This function advancedDecrementOp merely demonstrates the Advanced DECREMENT operation.
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Requires Eventing Storage (or metadata collection) and a "source" collection.
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Needs a Binding of type "bucket alias" (as documented in the Scriptlet).
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Will operate on any mutation and count down (decrement) the mutations subject to DCP dedup.
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For more information refer to Advanced DECREMENT operation in the detailed documentation.
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advancedDecrementOp
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Input Data/Mutation
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Output Data
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Output Log
javascript// 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);
}
}
jsonUPSERT 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
jsonKEY: my_atomic_counter:1
{
"count": -10
}
json2021-01-08T12:30:59.910-08:00 [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}