Dataflow write group

Use the Dataflow connector to write data by using a MutationGroup class to ensure that a group of mutations is applied atomically.

Explore further

For detailed documentation that includes this code sample, see the following:

• Import, export, and modify data using Dataflow

Code sample

Java

To learn how to install and use the client library for Spanner, see Spanner client libraries.

To authenticate to Spanner, set up Application Default Credentials. For more information, see Set up authentication for a local development environment.

PCollection<MutationGroup> mutations =
    suspiciousUserIds.apply(
        MapElements.via(
            new SimpleFunction<>() {

              @Override
              public MutationGroup apply(String userId) {
                // Immediately block the user.
                Mutation userMutation =
                    Mutation.newUpdateBuilder("Users")
                        .set("id")
                        .to(userId)
                        .set("state")
                        .to("BLOCKED")
                        .build();
                long generatedId =
                    Hashing.sha1()
                        .newHasher()
                        .putString(userId, Charsets.UTF_8)
                        .putLong(timestamp.getSeconds())
                        .putLong(timestamp.getNanos())
                        .hash()
                        .asLong();

                // Add an entry to pending review requests.
                Mutation pendingReview =
                    Mutation.newInsertOrUpdateBuilder("PendingReviews")
                        .set("id")
                        .to(generatedId) // Must be deterministically generated.
                        .set("userId")
                        .to(userId)
                        .set("action")
                        .to("REVIEW ACCOUNT")
                        .set("note")
                        .to("Suspicious activity detected.")
                        .build();

                return MutationGroup.create(userMutation, pendingReview);
              }
            }));

mutations.apply(SpannerIO.write()
    .withInstanceId(instanceId)
    .withDatabaseId(databaseId)
    .grouped());

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