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* 随机字符串函数的C语言实现
@ 2017-09-05 08:28 Quan Zongliang <zongliang.quan@postgresdata.com>
2017-09-05 09:01 ` Re: [pgsql-zh-general] 随机字符串函数的C语言实现 Jaimin Pan <jaimin.pan@gmail.com>
0 siblings, 1 reply; 5+ messages in thread
From: Quan Zongliang @ 2017-09-05 08:28 UTC (permalink / raw)
To: pgsql-zh-general
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
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.quan@postgresdata.com
--
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To make changes to your subscription:
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^ permalink raw reply [nested|flat] 5+ messages in thread
* Re: [pgsql-zh-general] 随机字符串函数的C语言实现
2017-09-05 08:28 随机字符串函数的C语言实现 Quan Zongliang <zongliang.quan@postgresdata.com>
@ 2017-09-05 09:01 ` Jaimin Pan <jaimin.pan@gmail.com>
2017-09-05 09:11 ` Re: Re: [pgsql-zh-general] 随机字符串函数的C语言实现 winston cheung <winston_cheung@163.com>
2017-09-05 10:26 ` Re: [pgsql-zh-general] 随机字符串函数的C语言实现 Quan Zongliang <zongliang.quan@postgresdata.com>
0 siblings, 2 replies; 5+ messages in thread
From: Jaimin Pan @ 2017-09-05 09:01 UTC (permalink / raw)
To: Quan Zongliang <zongliang.quan@postgresdata.com>; +Cc: pgsql-zh-general
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.quan@postgresdata.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[] = "0123456789ABCDEFGHIJKLMNOPQRS
> TUVWXYZabcdefghijklmnopqrstuvwxyz";
> 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
>
> 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.quan@postgresdata.com
>
>
>
> --
> Sent via pgsql-zh-general mailing list (pgsql-zh-general@postgresql.org)
> To make changes to your subscription:
> http://www.postgresql.org/mailpref/pgsql-zh-general
>
^ permalink raw reply [nested|flat] 5+ messages in thread
* Re: Re: [pgsql-zh-general] 随机字符串函数的C语言实现
2017-09-05 08:28 随机字符串函数的C语言实现 Quan Zongliang <zongliang.quan@postgresdata.com>
2017-09-05 09:01 ` Re: [pgsql-zh-general] 随机字符串函数的C语言实现 Jaimin Pan <jaimin.pan@gmail.com>
@ 2017-09-05 09:11 ` winston cheung <winston_cheung@163.com>
2017-09-06 01:48 ` Re: Re: [pgsql-zh-general] 随机字符串函数的C语言实现 Quan Zongliang <zongliang.quan@postgresdata.com>
1 sibling, 1 reply; 5+ messages in thread
From: winston cheung @ 2017-09-05 09:11 UTC (permalink / raw)
To: pgsql-zh-general
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.quan@postgresdata.com
> <mailto:zongliang.quan@postgresdata.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.quan@postgresdata.com
> <mailto:zongliang.quan@postgresdata.com>
>
>
>
> --
> Sent via pgsql-zh-general mailing list
> (pgsql-zh-general@postgresql.org
> <mailto:pgsql-zh-general@postgresql.org>)
> To make changes to your subscription:
> http://www.postgresql.org/mailpref/pgsql-zh-general
> <http://www.postgresql.org/mailpref/pgsql-zh-general;
>
>
^ permalink raw reply [nested|flat] 5+ messages in thread
* Re: Re: [pgsql-zh-general] 随机字符串函数的C语言实现
2017-09-05 08:28 随机字符串函数的C语言实现 Quan Zongliang <zongliang.quan@postgresdata.com>
2017-09-05 09:01 ` Re: [pgsql-zh-general] 随机字符串函数的C语言实现 Jaimin Pan <jaimin.pan@gmail.com>
2017-09-05 09:11 ` Re: Re: [pgsql-zh-general] 随机字符串函数的C语言实现 winston cheung <winston_cheung@163.com>
@ 2017-09-06 01:48 ` Quan Zongliang <zongliang.quan@postgresdata.com>
0 siblings, 0 replies; 5+ messages in thread
From: Quan Zongliang @ 2017-09-06 01:48 UTC (permalink / raw)
To: pgsql-zh-general
这篇博文有简单测试：
https://my.oschina.net/quanzl/blog/1529438
天壤之别的性能差距
On 2017/9/5 17:11, winston cheung wrote:
> 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.quan@postgresdata.com
>> <mailto:zongliang.quan@postgresdata.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.quan@postgresdata.com
>> <mailto:zongliang.quan@postgresdata.com>
>>
>>
>>
>> --
>> Sent via pgsql-zh-general mailing list
>> (pgsql-zh-general@postgresql.org
>> <mailto:pgsql-zh-general@postgresql.org>)
>> To make changes to your subscription:
>> http://www.postgresql.org/mailpref/pgsql-zh-general
>> <http://www.postgresql.org/mailpref/pgsql-zh-general;
>>
>>
>
--
Sent via pgsql-zh-general mailing list (pgsql-zh-general@postgresql.org)
To make changes to your subscription:
http://www.postgresql.org/mailpref/pgsql-zh-general
^ permalink raw reply [nested|flat] 5+ messages in thread
* Re: [pgsql-zh-general] 随机字符串函数的C语言实现
2017-09-05 08:28 随机字符串函数的C语言实现 Quan Zongliang <zongliang.quan@postgresdata.com>
2017-09-05 09:01 ` Re: [pgsql-zh-general] 随机字符串函数的C语言实现 Jaimin Pan <jaimin.pan@gmail.com>
@ 2017-09-05 10:26 ` Quan Zongliang <zongliang.quan@postgresdata.com>
1 sibling, 0 replies; 5+ messages in thread
From: Quan Zongliang @ 2017-09-05 10:26 UTC (permalink / raw)
To: Jaimin Pan <jaimin.pan@gmail.com>; +Cc: pgsql-zh-general
这样不能指定长度，返回值本身又不够长，今天测试是在看TOAST的变化。
On 2017/9/5 17:01, 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.quan@postgresdata.com <mailto:zongliang.quan@postgresdata.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.quan@postgresdata.com <mailto:zongliang.quan@postgresdata.com>
>
>
>
> --
> Sent via pgsql-zh-general mailing list
> (pgsql-zh-general@postgresql.org
> <mailto:pgsql-zh-general@postgresql.org>)
> To make changes to your subscription:
> http://www.postgresql.org/mailpref/pgsql-zh-general
> <http://www.postgresql.org/mailpref/pgsql-zh-general;
>
>
--
Sent via pgsql-zh-general mailing list (pgsql-zh-general@postgresql.org)
To make changes to your subscription:
http://www.postgresql.org/mailpref/pgsql-zh-general
^ permalink raw reply [nested|flat] 5+ messages in thread
end of thread, other threads:[~2017-09-06 01:48 UTC | newest]
Thread overview: 5+ messages (download: mbox mbox.gz follow: Atom feed)
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2017-09-05 08:28 随机字符串函数的C语言实现 Quan Zongliang <zongliang.quan@postgresdata.com>
2017-09-05 09:01 ` Jaimin Pan <jaimin.pan@gmail.com>
2017-09-05 09:11 ` winston cheung <winston_cheung@163.com>
2017-09-06 01:48 ` Quan Zongliang <zongliang.quan@postgresdata.com>
2017-09-05 10:26 ` Quan Zongliang <zongliang.quan@postgresdata.com>
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