May 2022 - Community - mailweb.opengauss.org

openGauss向量化引擎执行排序时内存统计的一个问题
by 闫宗帅 31 May '22

31 May '22

你好，在学习opengauss向量化引擎过程中，有一个疑惑，是不是遇到了bug？ openGauss向量化引擎在排序过程种，需要通过UseMem函数统计其内存使用。比如在Batchsortstate：：InitCommon函数中：第732行m_storeColumns.Init会申请对m_storeColumns.m_memValues申请10240* sizeof(MultiColumns));但是在第735行统计使用内存的时候，从m_storeColumns开始了，应该是从m_storeColumns.m_memValues这里开始才准确吧。这两个地址获取的GetMemoryChunkSpace大小明显不一样，通过修改代码分别获取下图中大小：得到的结果分别为： work_mem最小是64KB，在此情况下，光在第732行处就用掉了245816B，大概240KB，超过了64KB，应该LackMem报错的。但如果是代码中流程化，仅标记用了1064B。第735行是否应该修改为：UseMem(GetMemoryChunkSpace(m_storeColumn.m_memValues))

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关于展示openGauss社区核心代码仓库贡献总和的讨论
by Xiangxinyong (Edison) 30 May '22

30 May '22

Hi team，在下午的SIG Infra例会上，我们讨论了社区贡献看板：https://datastat.opengauss.org/zh/detail的单位成员贡献展示。当前openGauss社区有61个仓库：https://gitee.com/opengauss 后续考虑通过添加一个下拉框，用于展示在每个仓库的单位成员贡献。例会上讨论是否选出几个社区的核心代码仓库，在展示单个仓库贡献的同时，展示几个核心代码仓库的单位成员贡献总和。欢迎大家发表对展示几个核心代码仓库总和的看法？如果展示，我们选择哪些仓库作为核心代码仓库？ Best Regards, Edison Xiang

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回复郭炜亮
by 小徍 25 May '22

25 May '22

测试的功能是在线迁移还是离线迁移在线迁移的话检查一下进程是否正常建议把完整的迁移命令也发过来，方便定位问题可参照以下资料： https://opengauss.org/zh/blogs/blogs.html?post/totaj/%E5%A6%82%E4%BD%95%E4%…

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使用chameleon3.0 将MySQL迁移至openGauss不生效
by 郭炜亮 23 May '22

23 May '22

我使用chameleon将MySQL迁移至openGauss，日志没报错，但openGauss一直没有数据环境：CentOS7.6虚拟机，openGauss3.0，MySQL5.7，Chameleon_3.0.0 其中openGauss和MySQL装在同一台虚拟机中，迁移时使用的也是同一台虚拟机。 chameleon配置文件和迁移日志如下： -----default.yml文件内容如下：--------- --- # global settings pid_dir: '~/.pg_chameleon/pid/' log_dir: '~/.pg_chameleon/logs/' log_dest: file log_level: debug log_days_keep: 10 rollbar_key: '' rollbar_env: '' # type_override allows the user to override the default type conversion # into a different one. type_override:   "tinyint(1)":     override_to: boolean     override_tables:       - "*" # postgres  destination connection pg_conn:   host: "127.0.0.1"   port: "5432"   user: "opengauss_test"   password: "gauss_123"   database: "opengauss_database"   charset: "utf8" sources:   mysql:     readers: 4     writers: 4     db_conn:       host: "127.0.0.1"       port: "3306"       user: "mysql57_user"       password: "FireLight@Gwl99"       charset: 'utf8'       connect_timeout: 10000     schema_mappings:       db_mysql57_test: sch_mysql57_test     limit_tables:     skip_tables:     grant_select_to:     lock_timeout: "120s"     my_server_id: 100     replica_batch_size: 10000     replay_max_rows: 10000     batch_retention: '1 day'     copy_max_memory: "300M"     copy_mode: 'file'     out_dir: /tmp     sleep_loop: 1     on_error_replay: continue     on_error_read: continue     auto_maintenance: "disabled"     gtid_enable: false     type: mysql     keep_existing_schema: No     migrate_default_value: No -------default.yml文件内容结束------- ====================================================== -----------default_mysql.log 日志文件内容如下：----------- 2022-05-23 12:12:13 MainProcess INFO: Trying to add a new source 2022-05-23 12:12:13 MainProcess DEBUG: Checking if the source mysql already exists 2022-05-23 12:12:13 MainProcess WARNING: The source mysql already exists 2022-05-23 12:12:20 MainProcess INFO: Initialising the replica for source mysql 2022-05-23 12:12:20 MainProcess DEBUG: starting init replica for source mysql 2022-05-23 12:12:20 MainProcess DEBUG: There is already a database connection active. 2022-05-23 12:12:20 MainProcess DEBUG: Collecting schema mappings for source mysql 2022-05-23 12:12:20 MainProcess DEBUG: mysql version 5007038 2022-05-23 12:12:20 MainProcess INFO: deleting all the table references from the replica catalog for source mysql  2022-05-23 12:12:20 MainProcess DEBUG: Creating the loading schema _sch_linux_database_tmp. 2022-05-23 12:12:20 MainProcess DEBUG: Creating the destination schema sch_linux_database. 2022-05-23 12:12:20 MainProcess INFO: Swapping schema sch_linux_database with _sch_linux_database_tmp 2022-05-23 12:12:20 MainProcess DEBUG: Renaming schema sch_linux_database in _rename_sch_linux_database 2022-05-23 12:12:20 MainProcess DEBUG: Renaming schema _sch_linux_database_tmp in sch_linux_database 2022-05-23 12:12:20 MainProcess DEBUG: Renaming schema _rename_sch_linux_database in _sch_linux_database_tmp 2022-05-23 12:12:20 MainProcess DEBUG: Commit the swap transaction 2022-05-23 12:12:20 MainProcess DEBUG: Dropping the schema _sch_linux_database_tmp. 2022-05-23 12:12:20 MainProcess DEBUG: Changing the lock timeout for the session to 120s. 2022-05-23 12:12:20 MainProcess DEBUG: New log table : t_log_replica_mysql_1  2022-05-23 12:12:20 MainProcess INFO: Saved master data for source: mysql 2022-05-23 12:12:20 MainProcess DEBUG: Binlog file: mysql-bin.000001 2022-05-23 12:12:20 MainProcess DEBUG: Binlog position:1199 2022-05-23 12:12:20 MainProcess DEBUG: Last event: None 2022-05-23 12:12:20 MainProcess DEBUG: Next log table name: t_log_replica_mysql_1 2022-05-23 12:12:20 MainProcess DEBUG: Next batch id: 2 2022-05-23 12:12:20 MainProcess INFO: Set high watermark for source: mysql 2022-05-23 12:12:20 MainProcess INFO: init replica for source mysql is complete 2022-05-23 12:16:52 MainProcess DEBUG: There is already a database connection active. 2022-05-23 12:16:52 MainProcess DEBUG: Collecting schema mappings for source mysql 2022-05-23 12:16:52 MainProcess INFO: retrieving foreign keys metadata for schemas 'db_mysql57_test' 2022-05-23 12:16:52 MainProcess DEBUG: There is already a database connection active. 2022-05-23 12:16:52 MainProcess DEBUG: Collecting schema mappings for source mysql 2022-05-23 12:16:52 MainProcess DEBUG: Deleting the source mysql  2022-05-23 12:16:52 MainProcess DEBUG: There is already a database connection active. 2022-05-23 12:17:32 MainProcess INFO: Trying to add a new source 2022-05-23 12:17:32 MainProcess DEBUG: Checking if the source mysql already exists 2022-05-23 12:17:32 MainProcess DEBUG: Adding source mysql  2022-05-23 12:17:40 MainProcess INFO: Initialising the replica for source mysql 2022-05-23 12:17:40 MainProcess DEBUG: starting init replica for source mysql 2022-05-23 12:17:40 MainProcess DEBUG: There is already a database connection active. 2022-05-23 12:17:40 MainProcess DEBUG: Collecting schema mappings for source mysql 2022-05-23 12:17:40 MainProcess DEBUG: mysql version 5007038 2022-05-23 12:17:40 MainProcess INFO: deleting all the table references from the replica catalog for source mysql  2022-05-23 12:17:40 MainProcess DEBUG: Creating the loading schema _sch_mysql57_test_tmp. 2022-05-23 12:17:40 MainProcess DEBUG: Creating the destination schema sch_mysql57_test. 2022-05-23 12:17:41 reader-1 INFO: Copying the source table tb_customer into _sch_mysql57_test_tmp.tb_customer 2022-05-23 12:17:41 reader-1 DEBUG: estimating rows in db_mysql57_test.tb_customer 2022-05-23 12:17:41 reader-1 DEBUG: The table db_mysql57_test.tb_customer will be copied in 1  estimated slice(s) of 256 rows, using a transaction True 2022-05-23 12:17:41 reader-1 DEBUG: locking the table `db_mysql57_test`.`tb_customer` 2022-05-23 12:17:41 reader-1 DEBUG: collecting the master's coordinates for table `db_mysql57_test`.`tb_customer` 2022-05-23 12:17:41 reader-1 DEBUG: Executing query for table db_mysql57_test.tb_customer 2022-05-23 12:17:41 reader-1 DEBUG: set isolation level 2022-05-23 12:17:41 reader-1 DEBUG: beginning transaction 2022-05-23 12:17:41 reader-1 DEBUG: unlocking the tables 2022-05-23 12:17:41 reader-1 DEBUG: rolling back 2022-05-23 12:17:41 writer-3 DEBUG: Building DDL for index PRIMARY 2022-05-23 12:17:41 writer-3 INFO: Building index pk_tb_customer_1653279461_0 on _sch_mysql57_test_tmp.tb_customer 2022-05-23 12:17:41 writer-1 DEBUG: Table db_mysql57_test.tb_customer copied 1 slice of 1 2022-05-23 12:17:41 MainProcess INFO: Swapping schema sch_mysql57_test with _sch_mysql57_test_tmp 2022-05-23 12:17:41 MainProcess DEBUG: Renaming schema sch_mysql57_test in _rename_sch_mysql57_test 2022-05-23 12:17:41 MainProcess DEBUG: Renaming schema _sch_mysql57_test_tmp in sch_mysql57_test 2022-05-23 12:17:41 MainProcess DEBUG: Renaming schema _rename_sch_mysql57_test in _sch_mysql57_test_tmp 2022-05-23 12:17:41 MainProcess DEBUG: Commit the swap transaction 2022-05-23 12:17:41 MainProcess DEBUG: Dropping the schema _sch_mysql57_test_tmp. 2022-05-23 12:17:41 MainProcess DEBUG: Changing the lock timeout for the session to 120s. 2022-05-23 12:17:41 MainProcess DEBUG: New log table : t_log_replica_mysql_2  2022-05-23 12:17:41 MainProcess INFO: Saved master data for source: mysql 2022-05-23 12:17:41 MainProcess DEBUG: Binlog file: mysql-bin.000001 2022-05-23 12:17:41 MainProcess DEBUG: Binlog position:1199 2022-05-23 12:17:41 MainProcess DEBUG: Last event: None 2022-05-23 12:17:41 MainProcess DEBUG: Next log table name: t_log_replica_mysql_2 2022-05-23 12:17:41 MainProcess DEBUG: Next batch id: 1 2022-05-23 12:17:41 MainProcess INFO: Set high watermark for source: mysql 2022-05-23 12:17:41 MainProcess INFO: init replica for source mysql is complete 2022-05-23 14:27:45 MainProcess DEBUG: There is already a database connection active. 2022-05-23 14:27:45 MainProcess DEBUG: Collecting schema mappings for source mysql 2022-05-23 14:27:45 MainProcess INFO: retrieving foreign keys metadata for schemas 'db_mysql57_test' 2022-05-23 14:27:45 MainProcess DEBUG: There is already a database connection active. 2022-05-23 14:27:45 MainProcess DEBUG: Collecting schema mappings for source mysql 2022-05-23 14:27:45 MainProcess DEBUG: Deleting the source mysql  2022-05-23 14:27:45 MainProcess DEBUG: There is already a database connection active. 2022-05-23 14:41:58 MainProcess DEBUG: There is already a database connection active. 2022-05-23 14:42:36 MainProcess DEBUG: There is already a database connection active. 2022-05-23 14:44:37 MainProcess INFO: Initialising the replica for source mysql 2022-05-23 14:44:37 MainProcess DEBUG: starting init replica for source mysql 2022-05-23 14:44:37 MainProcess DEBUG: There is already a database connection active. 2022-05-23 14:44:37 MainProcess DEBUG: Collecting schema mappings for source mysql 2022-05-23 14:44:37 MainProcess DEBUG: mysql version 5007038 2022-05-23 14:44:37 MainProcess INFO: deleting all the table references from the replica catalog for source mysql  2022-05-23 14:44:37 MainProcess DEBUG: Creating the loading schema _sch_mysql57_test_tmp. 2022-05-23 14:44:37 MainProcess DEBUG: Creating the destination schema sch_mysql57_test. 2022-05-23 14:44:37 reader-3 INFO: Copying the source table tb_customer into _sch_mysql57_test_tmp.tb_customer 2022-05-23 14:44:37 reader-3 DEBUG: estimating rows in db_mysql57_test.tb_customer 2022-05-23 14:44:37 reader-3 DEBUG: The table db_mysql57_test.tb_customer will be copied in 1  estimated slice(s) of 256 rows, using a transaction True 2022-05-23 14:44:37 reader-3 DEBUG: locking the table `db_mysql57_test`.`tb_customer` 2022-05-23 14:44:37 reader-3 DEBUG: collecting the master's coordinates for table `db_mysql57_test`.`tb_customer` 2022-05-23 14:44:37 reader-3 DEBUG: Executing query for table db_mysql57_test.tb_customer 2022-05-23 14:44:37 reader-3 DEBUG: set isolation level 2022-05-23 14:44:37 reader-3 DEBUG: beginning transaction 2022-05-23 14:44:37 reader-3 DEBUG: unlocking the tables 2022-05-23 14:44:37 reader-3 DEBUG: rolling back 2022-05-23 14:44:38 writer-1 DEBUG: Building DDL for index PRIMARY 2022-05-23 14:44:38 writer-1 INFO: Building index pk_tb_customer_1653288278_0 on _sch_mysql57_test_tmp.tb_customer 2022-05-23 14:44:38 writer-2 DEBUG: Table db_mysql57_test.tb_customer copied 1 slice of 1 2022-05-23 14:44:38 MainProcess INFO: Swapping schema sch_mysql57_test with _sch_mysql57_test_tmp 2022-05-23 14:44:38 MainProcess DEBUG: Renaming schema sch_mysql57_test in _rename_sch_mysql57_test 2022-05-23 14:44:38 MainProcess DEBUG: Renaming schema _sch_mysql57_test_tmp in sch_mysql57_test 2022-05-23 14:44:38 MainProcess DEBUG: Renaming schema _rename_sch_mysql57_test in _sch_mysql57_test_tmp 2022-05-23 14:44:38 MainProcess DEBUG: Commit the swap transaction 2022-05-23 14:44:38 MainProcess DEBUG: Dropping the schema _sch_mysql57_test_tmp. 2022-05-23 14:44:38 MainProcess DEBUG: Changing the lock timeout for the session to 120s. 2022-05-23 14:44:38 MainProcess DEBUG: New log table : t_log_replica_mysql_2  2022-05-23 14:44:38 MainProcess INFO: Saved master data for source: mysql 2022-05-23 14:44:38 MainProcess DEBUG: Binlog file: mysql-bin.000002 2022-05-23 14:44:38 MainProcess DEBUG: Binlog position:154 2022-05-23 14:44:38 MainProcess DEBUG: Last event: None 2022-05-23 14:44:38 MainProcess DEBUG: Next log table name: t_log_replica_mysql_2 2022-05-23 14:44:38 MainProcess DEBUG: Next batch id: 1 2022-05-23 14:44:38 MainProcess INFO: Set high watermark for source: mysql 2022-05-23 14:44:38 MainProcess INFO: init replica for source mysql is complete 2022-05-23 14:53:26 MainProcess DEBUG: There is already a database connection active. 2022-05-23 14:53:26 MainProcess DEBUG: Collecting schema mappings for source mysql 2022-05-23 14:53:26 MainProcess INFO: retrieving foreign keys metadata for schemas 'db_mysql57_test' 2022-05-23 14:53:26 MainProcess DEBUG: There is already a database connection active. 2022-05-23 14:53:26 MainProcess DEBUG: Collecting schema mappings for source mysql 2022-05-23 14:53:26 MainProcess DEBUG: Deleting the source mysql  2022-05-23 14:53:26 MainProcess DEBUG: There is already a database connection active. ----------default_mysql.log 日志文件内容结束------------

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current of 语法支持问题
by liuf＠geoscene.cn 19 May '22

19 May '22

您好： openGauss现在不支持update table where current of 语法问题，我看了下源码，这部分的代码是强制被关闭了，我打开之后发现单机是可以正常运行的，那当时关闭这部分代码是处于什么考虑呢，是因为分布式所以不支持了吗。刘锋易智瑞信息技术有限公司

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有关单节点和分布式部署
by tommy 18 May '22

18 May '22

下图提到的分布式OpenGauss：是不是就是下载页面上的这个： OpenGauss 同时提供单节点和分布式多节点两种部署模式吗？

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请问如何修改opengauss 用户的密码？
by tommy 17 May '22

17 May '22

忘记了原来的密码，现在如何修改呢？ opengauss=# alter user opengauss identified by 'Opengauss123' REPLACE ''; ERROR: The old password is invalid. opengauss=# opengauss=# opengauss=# opengauss=# opengauss=# alter user opengauss identified by 'Opengauss123' REPLACE 'opengauss'; ERROR: The old password is invalid. opengauss=# opengauss=#

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MOT页面、记录的内存结构，磁盘结构
by qinhao＠newland.com.cn 13 May '22

13 May '22

各位大佬好，我最近在学习OpenGauss MOT部分的代码，但是相关解释文档比较少，目前我比较感兴趣的是MOT记录在内存中的结构，是像Postgres那样页的格式吗？能够给予一些提示或文档，还有与MOT表对应的磁盘中的数据格式是怎样的？我问这些，是想看一下实现增删列定义的难度怎样，这是我们大概率用到的一个特性。新大陆软件秦浩 mobile: 17625988619 e-mail:qinhao@newland.com.cn

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Re: [DISCUSS] Proposal for improving openGauss performance.
by pengjiong 12 May '22

12 May '22

Hi ` mysqlonarm`, thanks for your proposals, I think you'd better join the SIG conference, and introduce your idea to us, then we can understand you better. For incremental checkpoint part, I suggest you introduce it to the storage SIG, for unique sql part, I suggest you introduce it to the SQL SIG.

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在存储过程和函数中，MOT表可以JOIN磁盘表？
by qinhao＠newland.com.cn 12 May '22

12 May '22

今天，在存储过程中使用MOT表时，发现MOT表可以JOIN磁盘表，文档中说MOT不支持跨引擎查询，在gsql终端查询MOT和磁盘表做JOIN报错，但是把跨引擎查询的SQL放在存储过程或者函数中，发现是可以正常执行的，在plpgsql语句块里也是可以的。这个功能对我们是有用的，是不是说，可以一把MOT跨引擎查询放在plpgsql代码块里？或者这是个bug？下面是我的测试用例： create table emp1( empno int primary key, ename varchar(10), job varchar(9), deptno numeric(2)); INSERT INTO emp1 VALUES (1,'SMITH','CLERK',20); INSERT INTO emp1 VALUES (2,'ALLEN','SALESMAN',10); INSERT INTO emp1 VALUES (3,'WARD','SALESMAN',30); create foreign table emp1mot( empno int primary key, ename varchar(10), job varchar(9), deptno numeric(2)); INSERT INTO emp1mot VALUES (1,'SMITH','CLERK',60); INSERT INTO emp1mot VALUES (2,'ALLEN','SALESMAN',50); INSERT INTO emp1mot VALUES (3,'WARD','SALESMAN',40); INSERT INTO emp1mot VALUES (4,'JONES','MANAGER',30); INSERT INTO emp1mot VALUES (5,'JONES','MANAGER',20); CREATE OR REPLACE PROCEDURE proc1() AS DECLARE rec record; BEGIN for rec in (select * from emp1 e1 join emp1mot e1m on e1.deptno = e1m.deptno) loop RAISE NOTICE '%, %, %, %', rec."empno", rec."ename", rec."job", rec."deptno"; end loop; END; / call proc1(); 新大陆软件秦浩 mobile: 17625988619 e-mail:qinhao@newland.com.cn

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只读事务中 MOT表JOIN磁盘表
by qinhao＠newland.com.cn 10 May '22

10 May '22

目前MOT表不能JOIN磁盘表，两种表也不能放在一个事务里操作，我猜测可能是两种表的并发控制机制无法兼容。不过我们可能会用到这一功能，是不是可以开发一种只读事务，在这种事务中，可以JOIN MOT表和磁盘表，请问是否已经有类似机制或功能？新大陆软件秦浩 mobile: 17625988619 e-mail:qinhao@newland.com.cn

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[DISCUSS] Proposal for improving openGauss performance.
by 270162781＠qq.com 10 May '22

10 May '22

Hi, openGauss team and guys in community. We are very happy that we can get a chance to contribute some enhancement proposals to openGauss community. openGauss is a fast grown-up community and database. So we are eager to involve and work with u guys. Via the in-depth study from `mysqlonarm` (gitee id) in our team, we found some interesting stuff in openGauss, tried the best to provide the solution and coding. Such as  https://gitee.com/opengauss/openGauss-server/issues?assignee_id=&author… There are 4 issues we had been raised in openGauss. Most of them brings the benifits towards the performance. For example,  1. Suggest for incremental checkpoint in read-only workload. https://gitee.com/opengauss/openGauss-server/issues/I50EYL?from=project-iss… 2. This is a global counter optimization, if you are interested, please see the details in issue. https://gitee.com/opengauss/openGauss-server/issues/I53QUI?from=project-iss… 3. This one has potential optimize openGauss select workload in range to 5-13%. https://gitee.com/opengauss/openGauss-server/issues/I51KOD?from=project-iss… 4. This one helps improve the logic to add free buffers as part of incremental checkpoint, via our testing and apply the code in issue, it shows a wide range gain. (5-200%) for read workload, (50-100%) for write workload. https://gitee.com/opengauss/openGauss-server/issues/I56OAW?from=project-iss… All of aboves have potential work and worth to learn/test more for openGauss, we think those would make openGauss bettter sooner or later. We will try best to explore and contribute what we found in performance aspects. If you are interested in our improvement for openGauss, free feel to contact or discuss with us via email in openGauss ML. Regards!

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openGauss社区行为守则讨论
by xiangxinyong 07 May '22

07 May '22

openGauss社区从2020年6月30日至今，在不到2年的时间内，社区里面已经汇聚了700+合入PR的代码贡献者，感谢社区各位开发者一直以来的努力和贡献。社区除了既定的行为守则：https://gitee.com/opengauss/community/blob/master/code-of-condu… 实际是还有很多潜移默化的原则需要我们去遵循，我列举了如下几点，欢迎各位社区开发者来拍砖，一起修正完善。保持开放，平等的原则，社区里面不存在上下级关系，需要注意说话的方式和语气。在社区里面尽量使用英文提交Issue、 Pull Request（PR）、沟通交流，不要出现一些在公司内部的既定术语。建立良好的人际关系，乐于助人，社区里面受到尊敬是在于你做的事，而不在于你是社区里面的什么角色。避免在公司内部的交流，尽量在社区代码托管平台Issue、 Pull Request（PR）、邮件列表、微信群等公开渠道讨论。在社区里面的Issue、 Pull Request（PR）需要他人帮忙回复时，请在Comments里面@他人的Gitee账号，便于他人及时查看你的消息。在社区里面提Issue时，详细描述程序出错的现象及操作步骤，报告缺陷，保持对Issue的关注，实时反馈补充关键信息。在公开渠道提问前要明白你在要求别人花时间回答，做足功课，在正确的场合用正确的方法提问。提交的Pull Request（PR）以尽量小的代码量和功能进行分割，代码量最好小于100行，以便Maintainer、Committer以及其他贡献者进行检视。简单功能，可以先实现再将补丁提交到社区，复杂功能，最好先到邮件列表讨论，提出自己的设计方案和代码框架，遵循软件开发的全生命周期管理。经常向社区反馈进展，切忌将所有的代码完成后才向社区提交，正在进行中的Pull Request（PR）可以在Title前面添加【WIP】表示正在开发中。检视他人的代码，要仔细认真，不能确定的情况不要妄加评论。在发现社区有一些简单的拼写错误时，可以不用立即提交PR，可以在发现有大的修改时，随便修改这样的拼写错误。社区是大家的，并不属于任何一家公司。开源社区没有任何人会为问题或者需求提问负责，在提问时请尽量保持耐心。 Best Regards, Edison Xiang

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Hello
by 亮剑 07 May '22

07 May '22

Hello

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MOT 有buffer cache吗？
by qinhao＠newland.com.cn 05 May '22

05 May '22

我在尝试理解MOT的原理，请教一下，MOT不专门使用PostgreSQL那样的页缓存是吗？全局内存中存储的表，既是数据又是缓存，是吗？同时每个会话中，会缓存自己用到的页，是吗？新大陆软件秦浩 mobile: 17625988619 e-mail:qinhao@newland.com.cn

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MOT表支持外键吗？
by qinhao＠newland.com.cn 05 May '22

05 May '22

今天在尝试在MOT上创建外键，引用另一个MOT表，但是返回：ERROR: "emp3mot" is a mot, which does not support alter table. 想了解一下MOT表不支持外键吗？有没有什么支持外键的方法，或者有没有开发计划？新大陆软件秦浩 mobile: 17625988619 e-mail:qinhao@newland.com.cn

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