CODEWITHSUNDEEP
google-cloud-datastore
Chakrala.Srikanth
Chakrala.Srikanth

Reputation: 31

Joins in datastore

How to implement joins in datastore ,iam using java ,i want to insert a file(Excel,img,word or pdf) into datastore and retrive a file from datastore.

Upvotes: 0

Views: 2031

Answers (3)

APD
APD

Reputation: 1

you can't do joins in the datastore, a better option would be to filter entries as you go along. e.g., you want to join student entity with classes entity. You can't write a simple select s.student, c.class from student s join class c on s.class_id = c.class_id where... instead, do a filter on student first, get a set of those values ('foreign key') in a buffer and then use that buffer to filter on the other table, class

Upvotes: 0

Lily Yu
Lily Yu

Reputation: 1

Joins are not supported in GAE datastore, but you can use the latest service-CloudSQL

https://cloud.google.com/products/cloud-sql

See this documentation: https://developers.google.com/cloud-sql/docs/introduction

Upvotes: 0

libregeek
libregeek

Reputation: 1274

Joins are not supported in GAE. See this documentation: http://code.google.com/appengine/docs/java/datastore/jdo/relationships.html

If you are looking for an RDBMS style database in GAE, then Google Cloud SQL would be your choice: http://code.google.com/apis/sql/docs/developers_guide_java.html

Upvotes: 1

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