Distributed DDL improvements #21535
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Distributed DDL improvements #21535
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robot-clickhouse
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pr-improvement
nikitamikhaylov
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Mar 29, 2021
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| ClusterPtr new_cluster = getClusterImpl(); | ||
| std::lock_guard lock{mutex}; |
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Maybe move this line above previous? Because many threads will try construct a cluster... And it seems that you can lock mutex only once at the beginning of the method without additional scopes.
| @@ -120,7 +141,7 @@ ClusterPtr DatabaseReplicated::getCluster() const | |||
| hosts = zookeeper->getChildren(zookeeper_path + "/replicas", &stat); | |||
| if (hosts.empty()) | |||
| throw Exception(ErrorCodes::LOGICAL_ERROR, "No hosts found"); | |||
| Int32 cver = stat.cversion; | |||
| Int32 cversion = stat.cversion; | |||
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Is there any useful information inside /replicas node itself (without children)? Maybe better to check version in addition to cversion?
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As for now /replicas node does not store any informatin
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Changelog category (leave one):
Changelog entry (a user-readable short description of the changes that goes to CHANGELOG.md):
distributed_ddl_entry_format_versionto 2 to enable this.distributed_ddl_output_modesetting. Supported modes:none,throw(default),null_status_on_timeoutandnever_throw.Replicateddatabase engine.Detailed description / Documentation draft:
When
distributed_ddl_output_modeis set tothrowdistributed DDL query returns result set with query execution status for all hosts where query is finished. If query has failed on some hosts, then it will rethrow the first exception. If query is not finished yet on some hosts anddistributed_ddl_task_timeoutexceeded, then it throwsTIMEOUT_EXCEEDEDexception.noneis similar tothrow, but distributed DDL query returns no result set.null_status_on_timeoutmeans returnNULLas execution status in some rows of result set instead of throwingTIMEOUT_EXCEEDEDif query is not finished on the corresponding hosts.never_throwmeans do not throwTIMEOUT_EXCEEDEDand do not rethrow exceptions if query has failed on some hosts.