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There are many places in FE where a group of BE nodes needs to be selected according to certain requirements. for example:
1. When creating replicas for a tablet.
2. When selecting a BE to execute Insert.
3. When Stream Load forwards http requests to BE nodes.
These operations all have the same logic. So this CL mainly changes:
1. Create a new `BeSelectionPolicy` class to describe the set of conditions for selecting BE.
2. The logic of selecting BE nodes in `SystemInfoService` has been refactored, and the following two methods are used uniformly:
1. `selectBackendIdsByPolicy`: Select the required number of BE nodes according to the `BeSelectionPolicy`.
2. `selectBackendIdsForReplicaCreation`: Select the BE node for the replica creation operation.
Note that there are some changes here:
For the replica creation operation, the round-robin method was used to select BE nodes before,
but now it is changed to `random` selection for the following reasons:
1. Although the previous logic is round-robin, it is actually random.
2. The final diff of the random algorithm will not be greater than 5%, so it can be considered that the random algorithm
can distribute the data evenly.
Apache Doris (incubating)
Doris is an MPP-based interactive SQL data warehousing for reporting and analysis. Its original name was Palo, developed in Baidu. After donated to Apache Software Foundation, it was renamed Doris.
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Doris provides high concurrent low latency point query performance, as well as high throughput queries of ad-hoc analysis.
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Doris provides batch data loading and real-time mini-batch data loading.
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Doris provides high availability, reliability, fault tolerance, and scalability.
The main advantages of Doris are the simplicity (of developing, deploying and using) and meeting many data serving requirements in a single system. For details, refer to Overview.
Official website: https://doris.apache.org/
License
Note
Some licenses of the third-party dependencies are not compatible with Apache 2.0 License. So you need to disable some Doris features to be complied with Apache 2.0 License. For details, refer to the
thirdparty/LICENSE.txt
Technology
Doris mainly integrates the technology of Google Mesa and Apache Impala, and it is based on a column-oriented storage engine and can communicate by MySQL client.
Compile and install
See Compilation
Getting start
See Basic Usage
Doris Connector
Doris provides support for Spark/Flink to read data stored in Doris through Connector, and also supports to write data to Doris through Connector.
apache/incubator-doris-flink-connector
apache/incubator-doris-spark-connector
Doris Manager
Doris provides one-click visual automatic installation and deployment, cluster management and monitoring tools for clusters.
apache/incubator-doris-manager
Report issues or submit pull request
If you find any bugs, feel free to file a GitHub issue or fix it by submitting a pull request.
Contact Us
Contact us through the following mailing list.
| Name | Scope | |||
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| dev@doris.apache.org | Development-related discussions | Subscribe | Unsubscribe | Archives |
Links
- Doris official site - https://doris.incubator.apache.org
- Developer Mailing list - dev@doris.apache.org. Mail to dev-subscribe@doris.apache.org, follow the reply to subscribe the mail list.
- Slack channel - Join the Slack