FAQ about open source Elasticsearch

curl -u elastic:<password> -XPOST "localhost:9200/<index_name>/_cache/clear?pretty"

• Clear the cache of all indexes

  curl localhost:9200/_cache/clear?pretty

• Clear the cache of a specific index

  curl localhost:9200/<index_name>/_cache/clear?pretty

• Clear the cache of multiple indexes

  curl localhost:9200/<index_name1>,<index_name2>,<index_name3>/_cache/clear?pretty

curl -XPOST 'localhost:9200/_cluster/reroute' -d '{
    "commands" : [ {
        "move" :
            {
              "index" : "test", "shard" : 0,
              "from_node" : "node1", "to_node" : "node2"
            }
        },
        {
          "allocate" : {
              "index" : "test", "shard" : 1, "node" : "node3"
          }
        }
    ]
}'

• If the query succeeds, the issue is caused by an invalid index name. In this case, change the index name. An index name can contain only letters, underscores (_), and digits.
• If the query fails, the issue is caused by an error in the index or your cluster. In this case, check whether your cluster stores the index and runs in a normal state.

PUT /_cluster/settings
{
    "persistent" : {
        "action": {
          "auto_create_index": "false"
        }
    }
}

• Shards are stored on different nodes. If the number of shards is set to a large value, more files need to be opened, and more interactions are required among the nodes. This decreases query performance.
• If the number of shards is set to a small value, each shard stores more data. This also decreases query performance.

PUT /_cluster/settings
{
  "persistent": {
     "action.destructive_requires_name": false
  }
}