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相关文章：ElasticSearch: 数据刷新相关的刷新间隔refresh_interval、刷新接口_refresh和刷新策略RefreshPolicy
默认情况下ElasticSearch索引的refresh_interval为1秒，这意味着数据写1秒才就可以被搜索到。
每次索引refresh会产生一个新的 lucene 段，这会导致频繁的 segment merge 行为，对系统 CPU 和 IO 占用都比较高。
如果产品对于实时性要求不高，则可以降低刷新周期，如：index.refresh_interval: 120s。
但是这种特性对于功能测试来说比较麻烦：
sleep一段时间，才能进行测试。sleep策略通过的case，也可能偶尔失败。为了解决上述问题，需要提供ElasticSearch增删改数据之后数据立即刷新的策略。
ElasticSearch 5.1.1org.elasticsearch.action.support.WriteRequestBuilder#setRefreshPolicy接口如下
/**
* Should this request trigger a refresh ({@linkplain RefreshPolicy#IMMEDIATE}), wait for a refresh (
* {@linkplain RefreshPolicy#WAIT_UNTIL}), or proceed ignore refreshes entirely ({@linkplain RefreshPolicy#NONE}, the default).
*/
@SuppressWarnings("unchecked")
default B setRefreshPolicy(RefreshPolicy refreshPolicy) {
request().setRefreshPolicy(refreshPolicy);
return (B) this;
}
枚举org.elasticsearch.action.support.WriteRequest.RefreshPolicy定义了三种策略：
/**
* Don't refresh after this request. The default.
*/
NONE,
/**
* Force a refresh as part of this request. This refresh policy does not scale for high indexing or search throughput but is useful
* to present a consistent view to for indices with very low traffic. And it is wonderful for tests!
*/
IMMEDIATE,
/**
* Leave this request open until a refresh has made the contents of this request visible to search. This refresh policy is
* compatible with high indexing and search throughput but it causes the request to wait to reply until a refresh occurs.
*/
WAIT_UNTIL;
可知有以下三种刷新策略：
RefreshPolicy#IMMEDIATE:
RefreshPolicy#WAIT_UNTIL:
RefreshPolicy#NONE:
实现此接口的主要类如下：
DeleteRequestBuilderIndexRequestBuilderUpdateRequestBuilderBulkRequestBuilder/**
* ElasticSearch立即更新的示例代码
*/
@Test
public void refreshImmediatelyTest() {
//删除操作
client.prepareDelete("index", "type", "1").setRefreshPolicy(WriteRequest.RefreshPolicy.IMMEDIATE).get();
//索引操作
client.prepareIndex("index", "type", "2").setSource("{\"age\":1}").setRefreshPolicy(WriteRequest.RefreshPolicy.IMMEDIATE).get();
//更新操作
client.prepareUpdate("index", "type", "3").setDoc("{\"age\":1}").setRefreshPolicy(WriteRequest.RefreshPolicy.IMMEDIATE).get();
//批量操作
client.prepareBulk()
.add(client.prepareDelete("index", "type", "1"))
.add(client.prepareIndex("index", "type", "2").setSource("{\"age\":1}"))
.add(client.prepareUpdate("index", "type", "3").setDoc("{\"age\":1}"))
.setRefreshPolicy(WriteRequest.RefreshPolicy.IMMEDIATE).get();
}
