[COUCHDB-812] implement randomization in views resultset

• Type: Wish
• Status: Closed
• Priority: Minor
• Resolution: Won't Fix
• Affects Version/s: 0.11
• Component/s: Database Core
• Labels: merge rcouch

Environment

CouchDB

• Skill Level: Regular Contributors Level (Easy to Medium)
• Assignee: Unassigned
• Reporter: Michael Bailly
• Created: 28/Jun/10 14:45
• Updated: 02/Sep/18 06:31
• Resolved: 02/Sep/18 06:31

Description

This is a proposal for a new feature in CouchDB : allow a randomization of rows in a view response. We can for example add a randomize query parameter...
This request would probably not return the same results for the same request.

As an example :

GET /db/_design/doc/_view/example :
{
..
rows: [

{key: 1 ...}

,

{key: 2 ...}

,

{key: 3 ...}

]
}

GET /db/_design/doc/_view/example?randomize=true :
{
..
rows: [

{key: 2 ...}

,

{key: 3 ...}

,

{key: 1 ...}

]
}

GET /db/_design/doc/_view/example?randomize=true :
{
..
rows: [

{key: 1 ...}

,

{key: 3 ...}

,

{key: 2 ...}

]
}

This is a feature hard to implement client-side (but by reading all doc ids and use client-side random function). It's implemented by the RDBMS from ages, probably for the very same reasons : if we should read all the rows client-side to random-select some of them, performances are awful.