CODEWITHSUNDEEP
rethinkdb
abilash
abilash

Reputation: 897

Compound primary key in RethinkDB

Can I create compound primary key in RethinkDB ? For example if I have table with next documents strucure {authorsId: '371df80c-2efd-48f9-ac37-3edcdb152fb1', postsId: '905e0c92-adcb-4095-98df-fa08ca71b900'} how can I create primary key on both together authorsId and postsId. Or if I cannot do this how should I use many to many relationship in three tables way. Have I use one field as primary key and second as secondary index ?

Upvotes: 6

Views: 2903

Answers (2)

Oliver
Oliver

Reputation: 13031

Primary keys can only be on one column but you can put postsId and authorsId in an array and use that as primary key value.

See here for more information: https://www.rethinkdb.com/api/javascript/table_create/

EDIT

The primary key is still just one field but you can use [postsId, authorsId] as the value for that column and achieve the same. (added back from comment to answer).

Upvotes: 3

kureikain
kureikain

Reputation: 2314

RethinkDB primary key is for a single column, you can change it to any field instead of the default id. When you call tableCreate, you can pass a string for primaryKey to use that column as primary key.

You cannot create primary key on multiple columns. Though, you can create secondary index on multi columns. However, RethinkDB doesn't have the unique index effect https://github.com/rethinkdb/rethinkdb/issues/1716.

If you want to do many to many relation ships, use 3 tables, you can do this:

Table T1: id, fields

Table T2: id, fields2

Pivot table P: t1_id, t2_id

Then you can use eqJoin to join data, or concatMap/getAll. Example:

r.table("P").eq_join("t1_id", r.table("T1"))
  .zip()
  .eq_join("t2_id", r.table("T2"))
  .zip()

Basically from the pivot table, you join data with first table, then continue to join with second table.

You can read more about data table join https://www.rethinkdb.com/docs/table-joins/#many-to-many-relations in here.

Upvotes: 1

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