This returns all rows from both left and right tables, regardless of the condition. For rows where the condition is not met, null values will be returned for condition columns. The following query will return all the records from both the tables, but will have null values for rows that don't match on the joined columns:

#legacySQL
SELECT repos.repo_name,repos.watch_count,repocommits.author.name,repocommits.committer.name
FROM [bigquery-public-data:github_repos.sample_repos] repos
FULL OUTER JOIN EACH [bigquery-public-data:github_repos.sample_commits] repocommits
ON repos.repo_name = repocommits.repo_name
ORDER BY repos.repo_name