Is it possible for unique key to break master-master replication in mysql?












2















I have a master-master mysql setup with 2 servers running the exact same application making writes to such a table:



 CREATE TABLE `metric` (
`id` bigint(20) unsigned NOT NULL AUTO_INCREMENT,
`host` varchar(50) NOT NULL,
`userid` int(10) unsigned DEFAULT NULL,
`name` varchar(255) NOT NULL,
`sampleid` tinyint(3) unsigned NOT NULL,
PRIMARY KEY (`id`),
UNIQUE KEY `unique-metric` (`userid`,`host`,`name`,`sampleid`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8


auto_increment_increment is 2 and offsets are 0 and 1, so PK ids don't clash, but is it possible that with bad timing, 2 applications will create a row with an equal unique-metric index breaking replication on both mysql servers, since replication thread won't be able to insert replicated row into table due to another row already having the exact same index?










share|improve this question














bumped to the homepage by Community 16 mins ago


This question has answers that may be good or bad; the system has marked it active so that they can be reviewed.




















    2















    I have a master-master mysql setup with 2 servers running the exact same application making writes to such a table:



     CREATE TABLE `metric` (
    `id` bigint(20) unsigned NOT NULL AUTO_INCREMENT,
    `host` varchar(50) NOT NULL,
    `userid` int(10) unsigned DEFAULT NULL,
    `name` varchar(255) NOT NULL,
    `sampleid` tinyint(3) unsigned NOT NULL,
    PRIMARY KEY (`id`),
    UNIQUE KEY `unique-metric` (`userid`,`host`,`name`,`sampleid`)
    ) ENGINE=InnoDB DEFAULT CHARSET=utf8


    auto_increment_increment is 2 and offsets are 0 and 1, so PK ids don't clash, but is it possible that with bad timing, 2 applications will create a row with an equal unique-metric index breaking replication on both mysql servers, since replication thread won't be able to insert replicated row into table due to another row already having the exact same index?










    share|improve this question














    bumped to the homepage by Community 16 mins ago


    This question has answers that may be good or bad; the system has marked it active so that they can be reviewed.


















      2












      2








      2








      I have a master-master mysql setup with 2 servers running the exact same application making writes to such a table:



       CREATE TABLE `metric` (
      `id` bigint(20) unsigned NOT NULL AUTO_INCREMENT,
      `host` varchar(50) NOT NULL,
      `userid` int(10) unsigned DEFAULT NULL,
      `name` varchar(255) NOT NULL,
      `sampleid` tinyint(3) unsigned NOT NULL,
      PRIMARY KEY (`id`),
      UNIQUE KEY `unique-metric` (`userid`,`host`,`name`,`sampleid`)
      ) ENGINE=InnoDB DEFAULT CHARSET=utf8


      auto_increment_increment is 2 and offsets are 0 and 1, so PK ids don't clash, but is it possible that with bad timing, 2 applications will create a row with an equal unique-metric index breaking replication on both mysql servers, since replication thread won't be able to insert replicated row into table due to another row already having the exact same index?










      share|improve this question














      I have a master-master mysql setup with 2 servers running the exact same application making writes to such a table:



       CREATE TABLE `metric` (
      `id` bigint(20) unsigned NOT NULL AUTO_INCREMENT,
      `host` varchar(50) NOT NULL,
      `userid` int(10) unsigned DEFAULT NULL,
      `name` varchar(255) NOT NULL,
      `sampleid` tinyint(3) unsigned NOT NULL,
      PRIMARY KEY (`id`),
      UNIQUE KEY `unique-metric` (`userid`,`host`,`name`,`sampleid`)
      ) ENGINE=InnoDB DEFAULT CHARSET=utf8


      auto_increment_increment is 2 and offsets are 0 and 1, so PK ids don't clash, but is it possible that with bad timing, 2 applications will create a row with an equal unique-metric index breaking replication on both mysql servers, since replication thread won't be able to insert replicated row into table due to another row already having the exact same index?







      mysql replication






      share|improve this question













      share|improve this question











      share|improve this question




      share|improve this question










      asked Apr 8 '14 at 10:59









      FluffyFluffy

      1113




      1113





      bumped to the homepage by Community 16 mins ago


      This question has answers that may be good or bad; the system has marked it active so that they can be reviewed.







      bumped to the homepage by Community 16 mins ago


      This question has answers that may be good or bad; the system has marked it active so that they can be reviewed.
























          1 Answer
          1






          active

          oldest

          votes


















          0














          Though I've not tried this myself, I've done a quick documentation hunt and found that this part of the MySQL documentation is helpful.



          The relevant part is:




          If a statement produces different errors on the master and the slave, the slave SQL thread terminates, and the slave writes a message to its error log and waits for the database administrator to decide what to do about the error. This includes the case that a statement produces an error on the master or the slave, but not both.




          The next question would then be: "How do I know there has been an error?", to which I've found a useful script here, which could be run frequently as a cron task.






          share|improve this answer























            Your Answer








            StackExchange.ready(function() {
            var channelOptions = {
            tags: "".split(" "),
            id: "182"
            };
            initTagRenderer("".split(" "), "".split(" "), channelOptions);

            StackExchange.using("externalEditor", function() {
            // Have to fire editor after snippets, if snippets enabled
            if (StackExchange.settings.snippets.snippetsEnabled) {
            StackExchange.using("snippets", function() {
            createEditor();
            });
            }
            else {
            createEditor();
            }
            });

            function createEditor() {
            StackExchange.prepareEditor({
            heartbeatType: 'answer',
            autoActivateHeartbeat: false,
            convertImagesToLinks: false,
            noModals: true,
            showLowRepImageUploadWarning: true,
            reputationToPostImages: null,
            bindNavPrevention: true,
            postfix: "",
            imageUploader: {
            brandingHtml: "Powered by u003ca class="icon-imgur-white" href="https://imgur.com/"u003eu003c/au003e",
            contentPolicyHtml: "User contributions licensed under u003ca href="https://creativecommons.org/licenses/by-sa/3.0/"u003ecc by-sa 3.0 with attribution requiredu003c/au003e u003ca href="https://stackoverflow.com/legal/content-policy"u003e(content policy)u003c/au003e",
            allowUrls: true
            },
            onDemand: true,
            discardSelector: ".discard-answer"
            ,immediatelyShowMarkdownHelp:true
            });


            }
            });














            draft saved

            draft discarded


















            StackExchange.ready(
            function () {
            StackExchange.openid.initPostLogin('.new-post-login', 'https%3a%2f%2fdba.stackexchange.com%2fquestions%2f62747%2fis-it-possible-for-unique-key-to-break-master-master-replication-in-mysql%23new-answer', 'question_page');
            }
            );

            Post as a guest















            Required, but never shown

























            1 Answer
            1






            active

            oldest

            votes








            1 Answer
            1






            active

            oldest

            votes









            active

            oldest

            votes






            active

            oldest

            votes









            0














            Though I've not tried this myself, I've done a quick documentation hunt and found that this part of the MySQL documentation is helpful.



            The relevant part is:




            If a statement produces different errors on the master and the slave, the slave SQL thread terminates, and the slave writes a message to its error log and waits for the database administrator to decide what to do about the error. This includes the case that a statement produces an error on the master or the slave, but not both.




            The next question would then be: "How do I know there has been an error?", to which I've found a useful script here, which could be run frequently as a cron task.






            share|improve this answer




























              0














              Though I've not tried this myself, I've done a quick documentation hunt and found that this part of the MySQL documentation is helpful.



              The relevant part is:




              If a statement produces different errors on the master and the slave, the slave SQL thread terminates, and the slave writes a message to its error log and waits for the database administrator to decide what to do about the error. This includes the case that a statement produces an error on the master or the slave, but not both.




              The next question would then be: "How do I know there has been an error?", to which I've found a useful script here, which could be run frequently as a cron task.






              share|improve this answer


























                0












                0








                0







                Though I've not tried this myself, I've done a quick documentation hunt and found that this part of the MySQL documentation is helpful.



                The relevant part is:




                If a statement produces different errors on the master and the slave, the slave SQL thread terminates, and the slave writes a message to its error log and waits for the database administrator to decide what to do about the error. This includes the case that a statement produces an error on the master or the slave, but not both.




                The next question would then be: "How do I know there has been an error?", to which I've found a useful script here, which could be run frequently as a cron task.






                share|improve this answer













                Though I've not tried this myself, I've done a quick documentation hunt and found that this part of the MySQL documentation is helpful.



                The relevant part is:




                If a statement produces different errors on the master and the slave, the slave SQL thread terminates, and the slave writes a message to its error log and waits for the database administrator to decide what to do about the error. This includes the case that a statement produces an error on the master or the slave, but not both.




                The next question would then be: "How do I know there has been an error?", to which I've found a useful script here, which could be run frequently as a cron task.







                share|improve this answer












                share|improve this answer



                share|improve this answer










                answered Jan 22 '18 at 10:16









                NealeUNealeU

                1011




                1011






























                    draft saved

                    draft discarded




















































                    Thanks for contributing an answer to Database Administrators Stack Exchange!


                    • Please be sure to answer the question. Provide details and share your research!

                    But avoid



                    • Asking for help, clarification, or responding to other answers.

                    • Making statements based on opinion; back them up with references or personal experience.


                    To learn more, see our tips on writing great answers.




                    draft saved


                    draft discarded














                    StackExchange.ready(
                    function () {
                    StackExchange.openid.initPostLogin('.new-post-login', 'https%3a%2f%2fdba.stackexchange.com%2fquestions%2f62747%2fis-it-possible-for-unique-key-to-break-master-master-replication-in-mysql%23new-answer', 'question_page');
                    }
                    );

                    Post as a guest















                    Required, but never shown





















































                    Required, but never shown














                    Required, but never shown












                    Required, but never shown







                    Required, but never shown

































                    Required, but never shown














                    Required, but never shown












                    Required, but never shown







                    Required, but never shown







                    Popular posts from this blog

                    الفوسفات في المغرب

                    Four equal circles intersect: What is the area of the small shaded portion and its height

                    جامعة ليفربول