Scan consistency with AT_PLUS in CBQ

Couchbase Server
1

Can somebody help me with an example of AT_PLUS in CBQ? When I enable AT_PLUS with:

\SET -scan_consistency AT_PLUS;

Then every N1QL will error out with a “No scan_vector value”.

AT_PLUS with Java or .NET seems to be more straightforward from the various blog posts I’ve seen. Although, using the SDK it does not seem that the scan_vector needs to be calculated manually… :slight_smile:

I’m trying to do an UPDATE to a document and then SELECT COUNT(*) for it.

2

You need to set scan_vector value as described at https://developer.couchbase.com/documentation/server/5.0/settings/query-settings.html

cc @johan_larson

3

Thanks @vsr1. I saw that but still not sure how I would get these values:

Scan vectors are built of [value, guard] entries, two-element arrays:

value: a vbucket's sequence number (a JSON number)
guard: a vbucket's UUID (a string)
4

You shouldn’t try to do this manually. Use the SDK. It will automatically track the entries from KV operations, and supply them with the N1QL queries as scan vectors.

5

Thanks @johan_larson. I was just trying to do a quick test/proof of concept in CBQ instead of going into the SDK. I tried it with REQUEST_PLUS but I wanted more granular control with AT_PLUS .