This returns all data from the join condition columns of the right table and all matching data in the left table. All other rows in the left table that do not match the join condition will return null values in the condition column. The following RIGHT JOIN query will return the list of repositories from the sample_repos (LEFT-hand side of the join) table only if there is a record for that repository in the sample_commits table (RIGHT-hand-side table of the join). The EACH keyword is added to the join because the number of records in both the tables is very high. Use the EACH option if BigQuery throws a resources exceeded error when running your queries using JOIN:

#legacySQL
SELECT repos.repo_name, COUNT(repocommits.commit) as commit_count
FROM [bigquery-public-data:github_repos.sample_repos] repos
RIGHT JOIN EACH [bigquery-public-data:github_repos.sample_commits] repocommits
ON repos.repo_name = repocommits.repo_name
GROUP BY repos.repo_name
order by commit_count