Received: from malur.postgresql.org ([217.196.149.56]) by arkaria.postgresql.org with esmtp (Exim 4.84_2) (envelope-from ) id 1dpB4W-0000Aj-QE for pgsql-zh-general@arkaria.postgresql.org; Tue, 05 Sep 2017 10:27:08 +0000 Received: from localhost ([127.0.0.1] helo=postgresql.org) by malur.postgresql.org with smtp (Exim 4.84_2) (envelope-from ) id 1dpB4V-0004Ji-Tp for pgsql-zh-general@arkaria.postgresql.org; Tue, 05 Sep 2017 10:27:07 +0000 Received: from magus.postgresql.org ([2a02:c0:301:0:ffff::29]) by malur.postgresql.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_CBC_SHA384:256) (Exim 4.84_2) (envelope-from ) id 1dpB4V-0004GB-DU for pgsql-zh-general@postgresql.org; Tue, 05 Sep 2017 10:27:07 +0000 Received: from m97135.mail.qiye.163.com ([220.181.97.135]) by magus.postgresql.org with esmtp (Exim 4.84_2) (envelope-from ) id 1dpB4K-0006fo-Ao for pgsql-zh-general@postgresql.org; Tue, 05 Sep 2017 10:27:05 +0000 Received: from [192.168.0.165] (unknown [124.127.160.226]) by smtp1 (Coremail) with SMTP id h+CowABHj3vie65ZFAUoCQ--.27536S2; Tue, 05 Sep 2017 18:26:43 +0800 (CST) Subject: =?UTF-8?B?UmU6IFtwZ3NxbC16aC1nZW5lcmFsXSDpmo/mnLrlrZfnrKbkuLLlh70=?= =?UTF-8?B?5pWw55qEQ+ivreiogOWunueOsA==?= To: Jaimin Pan Cc: "pgsql-zh-general@postgresql.org" References: From: Quan Zongliang Message-ID: Date: Tue, 5 Sep 2017 18:26:42 +0800 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.12; rv:52.0) Gecko/20100101 Thunderbird/52.3.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 8bit X-CM-TRANSID: h+CowABHj3vie65ZFAUoCQ--.27536S2 X-Coremail-Antispam: 1Uf129KBjDUn29KB7ZKAUJUUUUU529EdanIXcx71UUUUU7v73 VFW2AGmfu7bjvjm3AaLaJ3UbIYCTnIWIevJa73UjIFyTuYvjTReHqsUUUUU X-Originating-IP: [124.127.160.226] X-CM-SenderInfo: p2rqwzpldqwhhtxd0qxsrv3wxuhvvt1wdou0bp/1tbiYARKGli2khcusQAAsA List-Archive: List-Help: List-ID: List-Owner: List-Post: List-Subscribe: List-Unsubscribe: X-Mailing-List: pgsql-zh-general Precedence: bulk Sender: pgsql-zh-general-owner@postgresql.org 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 > >: > > 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         { >                 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 > > > -- 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