分区表的` `bq ` update列上的并发扳手java堆栈跟踪

Question

我创建了一个sql，它对一列中的所有值进行更新

UPDATE `Blackout_POC2.measurements_2020`
SET visitor.customerId_enc = enc.encrypted
FROM `Blackout_POC2.encrypted` AS enc
WHERE dateAmsterdam="2020-01-05"
AND session.visitId = enc.visitId
AND visitor.customerId = enc.plain

其中dateAmsterdam是measurements_2020表的分区键，encrypted是一个非分区表，包含visitId、plain和encrypted字段。代码使用来自customerId_enc表的值设置encrypted列中的所有值。

当我一天一次运行它的时候，代码运行的非常好，但是当我并行运行几天时，我偶尔(1%左右)从我的bq query <sql>中得到一个堆栈跟踪(参见下面)。

我认为我可以在每个分区内并行地修改分区表，但有时情况并非如此。有人能告诉我这件事会被记录在哪里吗?最好是怎么避免的？我可能会再次重新运行这个查询，因为它是幂等的，但是我想知道为什么会发生这种情况。

谢谢

Bart van Deenen，数据工程师Bol.com

Error in query string: Error processing job 'bolcom-dev-blackout-339:bqjob_r131fa5b3dfd24829_0000016faec5e5da_1': domain: "cloud.helix.ErrorDomain"
code: "QUERY_ERROR" argument: "Could not serialize access to table bolcom-dev-blackout-339:Blackout_POC2.measurements_2020 due to concurrent update"
debug_info: "[CONCURRENT_UPDATE] Table modified by concurrent UPDATE/DELETE/MERGE DML or truncation at 1579185217979. Storage set job_uuid:
03d3d5ec-2118-4e43-9fec-1eae99402c86:20200106, instance_id: ClonedTable-1579183484786, Reason: code=CONCURRENT_UPDATE message=Could not serialize
access to table bolcom-dev-blackout-339:Blackout_POC2.measurements_2020 due to concurrent update debug=Table modified by concurrent UPDATE/DELETE/MERGE
DML or truncation at 1579185217979. Storage set job_uuid: 03d3d5ec-2118-4e43-9fec-1eae99402c86:20200106, instance_id: ClonedTable-1579183484786
errorProto=domain: \"cloud.helix.ErrorDomain\"\ncode: \"QUERY_ERROR\"\nargument: \"Could not serialize access to table bolcom-dev-
blackout-339:Blackout_POC2.measurements_2020 due to concurrent update\"\ndebug_info: \"Table modified by concurrent UPDATE/DELETE/MERGE DML or
truncation at 1579185217979. Storage set job_uuid: 03d3d5ec-2118-4e43-9fec-1eae99402c86:20200106, instance_id: ClonedTable-1579183484786\"\n\n\tat
com.google.cloud.helix.common.Exceptions$Public.concurrentUpdate(Exceptions.java:381)\n\tat
com.google.cloud.helix.common.Exceptions$Public.concurrentUpdate(Exceptions.java:373)\n\tat
com.google.cloud.helix.server.metadata.StorageTrackerData.verifyStorageSetUpdate(StorageTrackerData.java:224)\n\tat
com.google.cloud.helix.server.metadata.AtomicStorageTrackerSpanner.validateUpdates(AtomicStorageTrackerSpanner.java:1133)\n\tat
com.google.cloud.helix.server.metadata.AtomicStorageTrackerSpanner.updateStorageSets(AtomicStorageTrackerSpanner.java:1310)\n\tat
com.google.cloud.helix.server.metadata.AtomicStorageTrackerSpanner.updateStorageSets(AtomicStorageTrackerSpanner.java:1293)\n\tat
com.google.cloud.helix.server.metadata.MetaTableTracker.updateStorageSets(MetaTableTracker.java:2274)\n\tat
com.google.cloud.helix.server.job.StorageSideEffects$1.update(StorageSideEffects.java:1123)\n\tat
com.google.cloud.helix.server.job.StorageSideEffects$1.update(StorageSideEffects.java:976)\n\tat
com.google.cloud.helix.server.metadata.MetaTableTracker$1.update(MetaTableTracker.java:2510)\n\tat
com.google.cloud.helix.server.metadata.StorageTrackerSpanner.lambda$atomicUpdate$7(StorageTrackerSpanner.java:165)\n\tat
com.google.cloud.helix.server.metadata.AtomicStorageTrackerSpanner$Factory$1.run(AtomicStorageTrackerSpanner.java:3775)\n\tat com.google.cloud.helix.se
rver.metadata.AtomicStorageTrackerSpanner$Factory.lambda$performJobWithCommitResult$0(AtomicStorageTrackerSpanner.java:3792)\n\tat
com.google.cloud.helix.server.metadata.persistence.SpannerTransactionContext$RetryCountingWork.run(SpannerTransactionContext.java:1002)\n\tat com.googl
e.cloud.helix.server.metadata.persistence.SpannerTransactionContext$Factory.executeWithResultInternal(SpannerTransactionContext.java:840)\n\tat com.goo
gle.cloud.helix.server.metadata.persistence.SpannerTransactionContext$Factory.executeOptimisticWithResultInternal(SpannerTransactionContext.java:722)\n
\tat com.google.cloud.helix.server.metadata.persistence.SpannerTransactionContext$Factory.lambda$executeOptimisticWithResult$1(SpannerTransactionContex
t.java:716)\n\tat
com.google.cloud.helix.server.metadata.persistence.SpannerTransactionContext$Factory.executeWithMonitoring(SpannerTransactionContext.java:942)\n\tat co
m.google.cloud.helix.server.metadata.persistence.SpannerTransactionContext$Factory.executeOptimisticWithResult(SpannerTransactionContext.java:715)\n\ta
t com.google.cloud.helix.server.metadata.AtomicStorageTrackerSpanner$Factory.performJobWithCommitResult(AtomicStorageTrackerSpanner.java:3792)\n\tat
com.google.cloud.helix.server.metadata.AtomicStorageTrackerSpanner$Factory.performJobWithCommitResult(AtomicStorageTrackerSpanner.java:3720)\n\tat
com.google.cloud.helix.server.metadata.StorageTrackerSpanner.atomicUpdate(StorageTrackerSpanner.java:159)\n\tat
com.google.cloud.helix.server.metadata.MetaTableTracker.atomicUpdate(MetaTableTracker.java:2521)\n\tat com.google.cloud.helix.server.metadata.StatsRequ
estLoggingTrackers$LoggingStorageTracker.lambda$atomicUpdate$8(StatsRequestLoggingTrackers.java:494)\n\tat
com.google.cloud.helix.server.metadata.StatsRequestLoggingTrackers$StatsRecorder.record(StatsRequestLoggingTrackers.java:181)\n\tat
com.google.cloud.helix.server.metadata.StatsRequestLoggingTrackers$StatsRecorder.record(StatsRequestLoggingTrackers.java:158)\n\tat
com.google.cloud.helix.server.metadata.StatsRequestLoggingTrackers$StatsRecorder.access$500(StatsRequestLoggingTrackers.java:123)\n\tat
com.google.cloud.helix.server.metadata.StatsRequestLoggingTrackers$LoggingStorageTracker.atomicUpdate(StatsRequestLoggingTrackers.java:493)\n\tat
com.google.cloud.helix.server.job.StorageSideEffects.apply(StorageSideEffects.java:1238)\n\tat
com.google.cloud.helix.server.rosy.MergeStorageImpl.commitChanges(MergeStorageImpl.java:936)\n\tat
com.google.cloud.helix.server.rosy.MergeStorageImpl.merge(MergeStorageImpl.java:729)\n\tat
com.google.cloud.helix.server.rosy.StorageStubby.mergeStorage(StorageStubby.java:937)\n\tat
com.google.cloud.helix.proto2.Storage$ServiceParameters$21.handleBlockingRequest(Storage.java:2100)\n\tat
com.google.cloud.helix.proto2.Storage$ServiceParameters$21.handleBlockingRequest(Storage.java:2098)\n\tat
com.google.net.rpc3.impl.server.RpcBlockingApplicationHandler.handleRequest(RpcBlockingApplicationHandler.java:28)\n\tat
....

Answer 1

BigQuery DML操作不支持多语句事务；不过，您可以执行一些并发语句：

UPDATE and INSERT
DELETE and INSERT
INSERT and INSERT

例如，对表同时执行两个更新语句，其中只有一个会成功。

请记住，由于可以同时执行UPDATE和INSERT语句，另一个可能的原因是同时执行多个UPDATE语句。

您可以尝试使用脚本特性来防止管理执行流程并发。