下载安装，参考：https://github.com/yosa/predis

引入predis，例如：
require 'vendor/predis/predis/autoload.php'; //以实际路径为准
Predis\Autoloader::register();

使用：

$redis = new Predis\Client(
    [
        'host' => $redisInfo['path'],  //服务器地址
        'port' => $redisInfo['port'],  //端口
        'database' => $redisInfo['select'], //连接数据库
        'password' => $redisInfo['auth'], //密码
    ]
);
$redis->set("test", 11);
var_dump($redis->get("test")); //打印11

背景：
最近用es做数据检索，需要统计满足条件的zwk_zkrs字段的总和，特来记录一下
求和：

$params["body"]["aggs"]["total_zkrs"] = [
   "sum" => [
       "field" => "zwk_zkrs"
   ]
];
求平均值
$params["body"]["aggs"]["avg_zkrs"] = [
   "avg" => [
       "field" => "zwk_zkrs"
   ]
];

注：total_zkrs为自定义内容，sum为求和参数，avg为求平均值，zwk_zkrs为求和字段，
参考文献：
https://www.elastic.co/guide/cn/elasticsearch/guide/current/_aggregation_test_drive.html

$data = array(
  array(
    'id' => 5698,
    'first_name' => 'Bill',
    'last_name' => 'Gates',
  ),
  array(
    'id' => 4767,
    'first_name' => 'Steve',
    'last_name' => 'Aobs',
  ),
  array(
    'id' => 3809,
    'first_name' => 'Mark',
    'last_name' => 'Zuckerberg',
  )
);

//根据字段last_name对数组$data进行降序排列
$last_names = array_column($data,'last_name');
array_multisort($last_names,SORT_DESC,$data);

var_dump($data);

这个报错是因为连不上es服务端导致的
排查步骤:
1、查看host链接是否正确，例如：['http://127.0.0.1:9200']
2、确保host通信正常

以本地链接线上websocket为例，如图所示
var ws = new WebSocket("ws://127.0.0.1:6543");
ws.onopen = function()
{
ws.send(JSON.stringify({'type':'bind','uid':1}))
};
步骤一：如果请求域名为http,则可以正常访问，然而当域名为https时，就会报错，如下图所示

错误信息：Mixed Content: The page at ‘https://{域名}.com/‘ was loaded over HTTPS, but attempted to connect to the insecure WebSocket endpoint ‘ws://{ip}:{port}/‘. This request has been blocked; this endpoint must be available over WSS.
Uncaught DOMException: Failed to construct 'WebSocket': An insecure WebSocket connection may not be initiated from a page loaded over HTTPS

步骤二：根据错误提示信息，需要使用wss请求var ws = new WebSocket("wss://127.0.0.1:6543");

这时重新访问，会出现如下图所示信息
错误信息：failed：Error in connection establishment: newt::ERR_SSLPROTOCOL_ERROR
注：在使用https协议时，需要指定域名，这里换成ws = new WebSocket("wss://{域名}/wss");
同时修改nginx配置文件，在conf中加入以下代码
location /wss {
proxy_pass http://172.30.9.176:6543;
proxy_set_header X-Real-IP $remote_addr;
proxy_set_header Host $host;
proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;

proxy_http_version 1.1;
proxy_set_header Upgrade $http_upgrade;
proxy_set_header Connection "upgrade";

}
重启nginx服务后即可正常通讯