Why the config 'flushInterval' in ’application.yml‘ is bound to "index.refresh_interval"？

[coreyho]

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• Why do you submit this issue?
• Question or discussion
• Feature or performance improvement

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Question

Why the config 'flushInterval' in ’application.yml‘ is bound to "index.refresh_interval"？

org.apache.skywalking.oap.server.storage.plugin.elasticsearch.base.StorageEsInstaller#createSetting
setting.put("index.refresh_interval", record ? TimeValue.timeValueSeconds(10).toString() : TimeValue.timeValueSeconds(config.getFlushInterval()).toString());

The config also is bound to bulk flush interval in 'org.apache.skywalking.oap.server.library.module.ServiceNotProvidedException' ?

 this.registerServiceImplementation(IBatchDAO.class, new BatchProcessEsDAO(elasticSearch7Client, config.getBulkActions(), config.getFlushInterval(), config.getConcurrentRequests()));

These are two different configuration items.
What does this config mean？

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Requirement or improvement

Adding more config about elasticsearch such as 'index.merge.scheduler.max_thread_count' which is important and necessary.

[wu-sheng]

What do you mean why? Very confused about your questions. Json formated advanced attribute is for any extension configs of es index.

[coreyho]

'flush.Interval' and 'index_refresh_interval' are two different attributes in es, but there is only one corresponding config in skywalking. I Cannot set them to different value.

setting.put("index.refresh_interval", record ? TimeValue.timeValueSeconds(10).toString() : TimeValue.timeValueSeconds(config.getFlushInterval()).toString());
new BatchProcessEsDAO(elasticSearch7Client, config.getBulkActions(), config.getFlushInterval(), config.getConcurrentRequests())

And there is a config item corresponding 'index_refresh_interval' which is never be used.

[wu-sheng]

Because logically, they should be consistent from my understanding. Otherwise, dirty read happens.