Re: Re: [pgsql-zh-general] 随机字符串函数的C语言实现

权叔有性能测试么？列一下数据啊，哈哈，学习一下。

On 09/05/2017 05:01 PM, Jaimin Pan wrote:
> 试一试
> md5(random()::text);
>
>
> select pg_backend_pid(),s,'string '|| md5(random()::text) from (select
> generate_series(2000,8000,1) s) as g;
> Time: 239.733 ms
>
> 2017-09-05 16:28 GMT+08:00 Quan Zongliang
> <zongliang(dot)quan(at)postgresdata(dot)com
> <mailto:zongliang(dot)quan(at)postgresdata(dot)com>>:
>
> 各位下午好
> 邮件列表沉寂太久，激活一下大家的情绪。
>
> 分享一个C语言实现的随机字符串函数：
> PG_FUNCTION_INFO_V1(random_string);
> Datum
> random_string(PG_FUNCTION_ARGS)
> {
> int32 length = PG_GETARG_INT32(0);
> int32 i;
> const char chars[] =
> "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz";
> char *result;
>
> if (length < 0)
> PG_RETURN_NULL();
>
> if (length == 0)
> PG_RETURN_TEXT_P(cstring_to_text(""));
>
> result = palloc(length + 1);
> if (result == NULL)
> ereport(ERROR, (errcode(ERRCODE_OUT_OF_MEMORY),
> errmsg("out of memory")));
>
> for (i=0; i<length; i++)
> {
> result[i] = chars[random()%(sizeof(chars)-1)];
> }
> result[i] = '\0';
>
> PG_RETURN_TEXT_P(cstring_to_text(result));
> }
>
> 原文见：
> https://my.oschina.net/quanzl/blog/1529438
> <https://my.oschina.net/quanzl/blog/1529438>
>
> 欢迎关注我司公众号：postgresdata-news
>
> --
> 权宗亮
> 神州飞象（北京）数据科技有限公司
> 我们的力量源自最先进的开源数据库PostgreSQL
> zongliang(dot)quan(at)postgresdata(dot)com
> <mailto:zongliang(dot)quan(at)postgresdata(dot)com>
>
>
>
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