问题
Task: We have to setup a periodic sync of records from Spanner to Big Query. Our Spanner database has a relational table hierarchy.
Option Considered I was thinking of using Dataflow templates to setup this data pipeline.
Option1: Setup a job with Dataflow template 'Cloud Spanner to Cloud Storage Text' and then another with Dataflow template 'Cloud Storage Text to BigQuery'. Con: The first template works only on a single table and we have many tables to export.
Option2: Use 'Cloud Spanner to Cloud Storage Avro' template which exports the entire database. Con: I only need to export selected tables within a database and I don't see a template to import Avro into Big Query.
Questions: Please suggest what is the best option for setting up this pipeline
回答1:
Use a single Dataflow pipeline to do it in one shot/pass. Here's an example I wrote using the Java SDK to help get you started. It reads from Spanner, transforms it to a BigQuery TableRow using a ParDo, and then writes to BigQuery at the end. Under the hood it's using GCS, but that's all abstracted away from you as a user.
package org.polleyg;
import com.google.api.services.bigquery.model.TableFieldSchema;
import com.google.api.services.bigquery.model.TableRow;
import com.google.api.services.bigquery.model.TableSchema;
import com.google.cloud.spanner.Struct;
import org.apache.beam.runners.dataflow.options.DataflowPipelineOptions;
import org.apache.beam.sdk.Pipeline;
import org.apache.beam.sdk.io.gcp.bigquery.BigQueryIO;
import org.apache.beam.sdk.io.gcp.spanner.SpannerIO;
import org.apache.beam.sdk.options.PipelineOptionsFactory;
import org.apache.beam.sdk.transforms.DoFn;
import org.apache.beam.sdk.transforms.ParDo;
import org.apache.beam.sdk.values.PCollection;
import java.util.ArrayList;
import java.util.List;
import static org.apache.beam.sdk.io.gcp.bigquery.BigQueryIO.Write.CreateDisposition.CREATE_IF_NEEDED;
import static org.apache.beam.sdk.io.gcp.bigquery.BigQueryIO.Write.WriteDisposition.WRITE_TRUNCATE;
/**
* Do some randomness
*/
public class TemplatePipeline {
public static void main(String[] args) {
PipelineOptionsFactory.register(DataflowPipelineOptions.class);
DataflowPipelineOptions options = PipelineOptionsFactory.fromArgs(args).withValidation().as(DataflowPipelineOptions.class);
Pipeline pipeline = Pipeline.create(options);
PCollection<Struct> records = pipeline.apply("read_from_spanner",
SpannerIO.read()
.withInstanceId("spanner-to-dataflow-to-bq")
.withDatabaseId("the-dude")
.withQuery("SELECT * FROM Singers"));
records.apply("convert-2-bq-row", ParDo.of(new DoFn<Struct, TableRow>() {
@ProcessElement
public void processElement(ProcessContext c) throws Exception {
TableRow row = new TableRow();
row.set("id", c.element().getLong("SingerId"));
row.set("first", c.element().getString("FirstName"));
row.set("last", c.element().getString("LastName"));
c.output(row);
}
})).apply("write-to-bq", BigQueryIO.writeTableRows()
.to(String.format("%s:spanner_to_bigquery.singers", options.getProject()))
.withCreateDisposition(CREATE_IF_NEEDED)
.withWriteDisposition(WRITE_TRUNCATE)
.withSchema(getTableSchema()));
pipeline.run();
}
private static TableSchema getTableSchema() {
List<TableFieldSchema> fields = new ArrayList<>();
fields.add(new TableFieldSchema().setName("id").setType("INTEGER"));
fields.add(new TableFieldSchema().setName("first").setType("STRING"));
fields.add(new TableFieldSchema().setName("last").setType("STRING"));
return new TableSchema().setFields(fields);
}
}
Output logs:
00:10:54,011 0 [direct-runner-worker] INFO org.apache.beam.sdk.io.gcp.bigquery.BatchLoads - Writing BigQuery temporary files to gs://spanner-dataflow-bq/tmp/BigQueryWriteTemp/beam_load_templatepipelinegrahampolley0531141053eff9d0d4_3dd2ba3a1c0347cf860241ddcd310a12/ before loading them.
00:10:59,332 5321 [direct-runner-worker] INFO org.apache.beam.sdk.io.gcp.bigquery.TableRowWriter - Opening TableRowWriter to gs://spanner-dataflow-bq/tmp/BigQueryWriteTemp/beam_load_templatepipelinegrahampolley0531141053eff9d0d4_3dd2ba3a1c0347cf860241ddcd310a12/c374d44a-a7db-407e-aaa4-fe6aa5f6a9ef.
00:11:01,178 7167 [direct-runner-worker] INFO org.apache.beam.sdk.io.gcp.bigquery.WriteTables - Loading 1 files into {datasetId=spanner_to_bigquery, projectId=grey-sort-challenge, tableId=singers} using job {jobId=beam_load_templatepipelinegrahampolley0531141053eff9d0d4_3dd2ba3a1c0347cf860241ddcd310a12_b4b4722df4326c6f5a93d7824981dc73_00001_00000-0, location=australia-southeast1, projectId=grey-sort-challenge}, attempt 0
00:11:02,495 8484 [direct-runner-worker] INFO org.apache.beam.sdk.io.gcp.bigquery.BigQueryServicesImpl - Started BigQuery job: {jobId=beam_load_templatepipelinegrahampolley0531141053eff9d0d4_3dd2ba3a1c0347cf860241ddcd310a12_b4b4722df4326c6f5a93d7824981dc73_00001_00000-0, location=australia-southeast1, projectId=grey-sort-challenge}.
bq show -j --format=prettyjson --project_id=grey-sort-challenge beam_load_templatepipelinegrahampolley0531141053eff9d0d4_3dd2ba3a1c0347cf860241ddcd310a12_b4b4722df4326c6f5a93d7824981dc73_00001_00000-0
00:11:02,495 8484 [direct-runner-worker] INFO org.apache.beam.sdk.io.gcp.bigquery.WriteTables - Load job {jobId=beam_load_templatepipelinegrahampolley0531141053eff9d0d4_3dd2ba3a1c0347cf860241ddcd310a12_b4b4722df4326c6f5a93d7824981dc73_00001_00000-0, location=australia-southeast1, projectId=grey-sort-challenge} started
00:11:03,183 9172 [direct-runner-worker] INFO org.apache.beam.sdk.io.gcp.bigquery.BigQueryServicesImpl - Still waiting for BigQuery job beam_load_templatepipelinegrahampolley0531141053eff9d0d4_3dd2ba3a1c0347cf860241ddcd310a12_b4b4722df4326c6f5a93d7824981dc73_00001_00000-0, currently in status {"state":"RUNNING"}
bq show -j --format=prettyjson --project_id=grey-sort-challenge beam_load_templatepipelinegrahampolley0531141053eff9d0d4_3dd2ba3a1c0347cf860241ddcd310a12_b4b4722df4326c6f5a93d7824981dc73_00001_00000-0
00:11:05,043 11032 [direct-runner-worker] INFO org.apache.beam.sdk.io.gcp.bigquery.BigQueryServicesImpl - BigQuery job {jobId=beam_load_templatepipelinegrahampolley0531141053eff9d0d4_3dd2ba3a1c0347cf860241ddcd310a12_b4b4722df4326c6f5a93d7824981dc73_00001_00000-0, location=australia-southeast1, projectId=grey-sort-challenge} completed in state DONE
00:11:05,044 11033 [direct-runner-worker] INFO org.apache.beam.sdk.io.gcp.bigquery.WriteTables - Load job {jobId=beam_load_templatepipelinegrahampolley0531141053eff9d0d4_3dd2ba3a1c0347cf860241ddcd310a12_b4b4722df4326c6f5a93d7824981dc73_00001_00000-0, location=australia-southeast1, projectId=grey-sort-challenge} succeeded. Statistics: {"completionRatio":1.0,"creationTime":"1559311861461","endTime":"1559311863323","load":{"badRecords":"0","inputFileBytes":"81","inputFiles":"1","outputBytes":"45","outputRows":"2"},"startTime":"1559311862043","totalSlotMs":"218","reservationUsage":[{"name":"default-pipeline","slotMs":"218"}]}
回答2:
There is currently no off-the-shelf parameterized direct export from Cloud Spanner to BigQuery.
To meet your requirements, a custom dataflow job (spanner dataflow connector, dataflow templates) scheduled periodically (1, 2) would be the best bet. Incremental exports would require implementing change tracking in you database which can be done with commit timestamps.
For a no-code solution, you would have to relax your requirements and bulk export all tables periodically to Cloud Storage and bulk import them periodically into BigQuery. You could use a combination of a periodic trigger of an export from Cloud Spanner to Cloud Storage and schedule a periodic import from Cloud Storage to BigQuery.
来源：https://stackoverflow.com/questions/56337117/gcp-what-is-the-best-option-to-setup-a-periodic-data-pipeline-from-spanner-to-b