Elasticsearch Scroll 详解

Elasticsearch Scroll 是一种用于处理大量数据的机制，它允许我们在不影响性能的情况下，从 Elasticsearch 中检索大量数据。本攻略将细介绍 Elasticsearch Scroll 的使用方法，并提供两个示例说明。

Scroll 的基本原理

当我们从 Elasticsearch 中检索大量数据时，通常会使用分页机制。但是，使用分页机制会导致性能下降，因为每次检索都需要重新计算分页。而 Elasticsearch Scroll 机制则可以避免这个问题，它会在内中缓存数据，从而避免了重新计算分页的开销。

Scroll 的使用方法

使用 Elasticsearch Scroll 机制，需要执行以下步骤：

1. 执行初始搜索请求，并设置 scroll 参数。

{
    "size": 1000,
    "query": {
        "match_all": {}
    },
    "sort": [
        {
            "timestamp": {
                "order": "asc"
            }
        }
    ],
    "scroll": "1m"
}

1. 获取第一批数据，并记录 scroll_id。

“`json
{
“_scroll_id”: “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