Several days ago, I saw on my post a comment by @arcange, indicating that my query to SteemSQL affected the performance of the server. I contacted @arcange immediately. He kindly explained to me with patience that I should use `CONTAINS()` instead of `LIKE`, and  `depth=0` instead of `title = ''` to search efficiently. Now my search is much faster than before. Great thanks to @arcange! You can [vote](https://v2.steemconnect.com/sign/account-witness-vote?witness=arcange&approve=true) @arcange as a witness so as to support his great work!

This post tells the details of the story mentioned above. Hopefully it could help other SteemSQL users.

不久前，我的某篇帖子收到来自阿灿哥(arcange)的一条回复：

> Hello @dapeng,
>
> You are issuing query to SteemSQL that negatively impact the infrastructure performances and penalize others users.
> 
> Please contact me on [steem.chat](http://steem.chat/direct/arcange) or on Discord!
>

我英语不好，大概感觉是好像我不知怎地把 SteemSQL 服务器给破坏了，好像是捅了大漏子。这个问题不久前 @tvb 跟我讨论过，没想到现在轮到我了，吓得我赶紧去 chat 联系阿灿哥负荆请罪。

原以为会被骂一通，谁料想阿灿哥非常 nice，给我如此这般详细解释了一番。

他说，我在搜索 SteemSQL 数据库的时候，用的两个指令效率太低。一个是 `LIKE`，一个是` title <> ''`。例如，我搜索“华语好声音”活动的帖子时，搜索的条件是以 'cn-voice' 为标签 + 标题不为空：

```
SELECT 
    * 
FROM 
    Comments 
WHERE 
    title <> '' 
    AND
     json_metadata LIKE '%"cn-voice"%'
```

阿灿哥说，`LIKE`这个操作极度耗费资源。SteemSQL 最近支持对帖子的标题、正文和 json 元数据进行全文检索了，所以应该用 `CONTAINS`来代替 `LIKE`，并且用 `depth = 0` 来选取标题不为空的帖子（> 0的话就是选取评论）：

````
SELECT
    * 
FROM
     Comments 
WHERE 
    depth = 0 
    AND 
    CONTAINS(json_metadata, "cn-voice")
````

阿灿哥会说中文，特意告诉我支持中文检索哦，例如：

```
SELECT
    *
FROM
    Comments 
WHERE
    CONTAINS(title,  N'月旦评')
```

用了新方法之后，查询果然快多了，即使数据量大的时候，几秒也能查完，而原先则是需要几十秒甚至几分钟，我还以为是我电脑的问题。

我猜想肯定很多用户都遇到这个问题了，但是我还没看到专门说这个的帖子(如果有，请告诉我)，所以就写出来跟大家分享。

感谢阿灿哥！可以通过[投票](https://v2.steemconnect.com/sign/account-witness-vote?witness=arcange&approve=true) @arcange 当见证人来支持他。