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[GH-ISSUE #54] What is the optimal and/or recommended way to store Hierarchical data on CouchDB #329

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opened 2026-04-08 22:01:09 -06:00 by gitea-mirror · 2 comments

gitea-mirror commented

2026-04-08 22:01:09 -06:00

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Originally created by @jofomah on GitHub (Jun 24, 2015).
Original GitHub issue: https://github.com/jo/couchdb-best-practices/issues/54

This should make it easy and possible to do the following in one request:

Get all descendant of a node. E.g given a State Id, retrieve all location (State Zones, LGA, Ward and Health Facilities under the state), give a Ward Id, return LGA Id, return all (Wards and Health Facilities under the Ward) and Given a State Id, return a given level under it, maybe all Wards, all LGAs and all Health Facilities.
Able to get each Node's ancestors in one query.
Run other kinds of deeply nested queries.

Originally created by @jofomah on GitHub (Jun 24, 2015). Original GitHub issue: https://github.com/jo/couchdb-best-practices/issues/54 This should make it easy and possible to do the following in one request: - Get all descendant of a node. E.g given a State Id, retrieve all location (State Zones, LGA, Ward and Health Facilities under the state), give a Ward Id, return LGA Id, return all (Wards and Health Facilities under the Ward) and Given a State Id, return a given level under it, maybe all Wards, all LGAs and all Health Facilities. - Able to get each Node's ancestors in one query. - Run other kinds of deeply nested queries.

gitea-mirror commented

2026-04-08 22:01:11 -06:00

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@jofomah commented on GitHub (Jun 27, 2015):

Possible Answer:

i think i have found something that can work on CouchDB, i looked into patterns used to store hierarchical data on relational database

Adjacency list : won't work for me because i can't query deeply nested trees.
Path Enumeration: this will work unless there is a downside that am not seeing (edited)
in this case, i will just store each document's ancestors as an array property of the document
this is similar to @jo's suggestion to emit ([country, national level, state], doc), the only difference is that i won't have to store the ancestor as string property of the document e.g doc.stateId, doc.wardId, doc.lgaId but as array of ancestors i can use administrative levels not tied to any country's administrative level names.

but in this case, i will just emit each ancestor array element as key

for(var i in doc.ancestors){
  var ancestorId = doc.ancestors[i];
  emit(ancestorId)
}

var healthFacility = {

  "ancestors": ["NG", "NW", "KN"]
}

if i now query with key = stateId, where stateid = 'KN', i will be able to get all state sub-levels that has 'KN' as one of their ancestors, which what the current adjacent list am using could not give me. (edited)

@jofomah commented on GitHub (Jun 27, 2015): Possible Answer: i think i have found something that can work on CouchDB, i looked into patterns used to store hierarchical data on relational database - Adjacency list : won't work for me because i can't query deeply nested trees. - Path Enumeration: this will work unless there is a downside that am not seeing (edited) in this case, i will just store each document's ancestors as an array property of the document this is similar to @jo's suggestion to emit ([country, national level, state], doc), the only difference is that i won't have to store the ancestor as string property of the document e.g doc.stateId, doc.wardId, doc.lgaId but as array of ancestors i can use administrative levels not tied to any country's administrative level names. but in this case, i will just emit each ancestor array element as key ``` Javascript for(var i in doc.ancestors){ var ancestorId = doc.ancestors[i]; emit(ancestorId) } ``` ``` JSON var healthFacility = { "ancestors": ["NG", "NW", "KN"] } ``` if i now query with key = stateId, where stateid = 'KN', i will be able to get all state sub-levels that has 'KN' as one of their ancestors, which what the current adjacent list am using could not give me. (edited)

gitea-mirror commented

2026-04-08 22:01:11 -06:00

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@jo commented on GitHub (Jun 29, 2015):

This is a good solution. I recommend to emit the whole ancestors array:

function(doc) {
  emit(doc.ancestors)
}

This has two advantages over using one view per level:

ids do not have to be unique
require less disk space

But also a disadvantage:

you have to know the full path for querying

If you now want to get a list of all docs in state KN you query for the full path:

{
  "startkey": ["NG", "NW", "KN"],
  "endkey": ["NG", "NW", "KN", {}]
}

The same view returns all documents for a higher level:

{
  "startkey": ["NG", "NW"],
  "endkey": ["NG", "NW", {}]
}

@jo commented on GitHub (Jun 29, 2015): This is a good solution. I recommend to emit the whole `ancestors` array: ``` js function(doc) { emit(doc.ancestors) } ``` This has two advantages over using one view per level: - ids do not have to be unique - require less disk space But also a disadvantage: - you have to know the full path for querying If you now want to get a list of all docs in state `KN` you query for the full path: ``` json { "startkey": ["NG", "NW", "KN"], "endkey": ["NG", "NW", "KN", {}] } ``` The same view returns all documents for a higher level: ``` json { "startkey": ["NG", "NW"], "endkey": ["NG", "NW", {}] } ```

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Reference: github-starred/couchdb-best-practices#329

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