MySQL - lock row for reading












1















I am using socket.io server and multiple clients are making requests to this server. Server checks a MySQL innoDB table for data and if there is some data it updates its bit/column in table and send data to requested client.



But the problem is my multiple clients are occasionally getting same data.



Reason I feel is, 2 clients make requests to server exactly same point in time and both get same MySQL table row record before it was updated by other client.






mysql socket.io innodb







share|improve this question























  • If you use the received data in follow-up select, insert or update then you have to use FOR UPDATE or FOR SHARE within the transaction.

    – t.niese
    Nov 19 '18 at 10:06













  • Possible duplicate of Locking a row in a MYSQL table during a transaction

    – t.niese
    Nov 19 '18 at 10:10











  • How to properly use transactions and locks to ensure database integrity?

    – t.niese
    Nov 19 '18 at 10:10











  • @t.niese - the link you shared is something different. Those locking doesn't lock a row for reading. I want to lock read, means the row my one connection is processing should not be read by other connection.

    – Irfan DANISH
    Nov 19 '18 at 10:43











  • If you use FOR UPDATE then Other transactions are blocked from updating those rows, from doing SELECT ... FOR SHARE, or from reading the data in certain transaction isolation levels.. So if your isolation level is set up correctly then you can't have two transactions having a SELECT .. FOR UPDATE on the same row. So either the second transaction fails, or waits until the first FOR UPDATE finished.

    – t.niese
    Nov 19 '18 at 12:25


















1















I am using socket.io server and multiple clients are making requests to this server. Server checks a MySQL innoDB table for data and if there is some data it updates its bit/column in table and send data to requested client.



But the problem is my multiple clients are occasionally getting same data.



Reason I feel is, 2 clients make requests to server exactly same point in time and both get same MySQL table row record before it was updated by other client.






mysql socket.io innodb







share|improve this question























  • If you use the received data in follow-up select, insert or update then you have to use FOR UPDATE or FOR SHARE within the transaction.

    – t.niese
    Nov 19 '18 at 10:06













  • Possible duplicate of Locking a row in a MYSQL table during a transaction

    – t.niese
    Nov 19 '18 at 10:10











  • How to properly use transactions and locks to ensure database integrity?

    – t.niese
    Nov 19 '18 at 10:10











  • @t.niese - the link you shared is something different. Those locking doesn't lock a row for reading. I want to lock read, means the row my one connection is processing should not be read by other connection.

    – Irfan DANISH
    Nov 19 '18 at 10:43











  • If you use FOR UPDATE then Other transactions are blocked from updating those rows, from doing SELECT ... FOR SHARE, or from reading the data in certain transaction isolation levels.. So if your isolation level is set up correctly then you can't have two transactions having a SELECT .. FOR UPDATE on the same row. So either the second transaction fails, or waits until the first FOR UPDATE finished.

    – t.niese
    Nov 19 '18 at 12:25
















1












1








1








I am using socket.io server and multiple clients are making requests to this server. Server checks a MySQL innoDB table for data and if there is some data it updates its bit/column in table and send data to requested client.



But the problem is my multiple clients are occasionally getting same data.



Reason I feel is, 2 clients make requests to server exactly same point in time and both get same MySQL table row record before it was updated by other client.






mysql socket.io innodb







share|improve this question














I am using socket.io server and multiple clients are making requests to this server. Server checks a MySQL innoDB table for data and if there is some data it updates its bit/column in table and send data to requested client.



But the problem is my multiple clients are occasionally getting same data.



Reason I feel is, 2 clients make requests to server exactly same point in time and both get same MySQL table row record before it was updated by other client.






mysql socket.io innodb




mysql socket.io innodb






share|improve this question













share|improve this question











share|improve this question




share|improve this question










asked Nov 19 '18 at 10:04









Irfan DANISHIrfan DANISH

4,88283155




4,88283155













  • If you use the received data in follow-up select, insert or update then you have to use FOR UPDATE or FOR SHARE within the transaction.

    – t.niese
    Nov 19 '18 at 10:06













  • Possible duplicate of Locking a row in a MYSQL table during a transaction

    – t.niese
    Nov 19 '18 at 10:10











  • How to properly use transactions and locks to ensure database integrity?

    – t.niese
    Nov 19 '18 at 10:10











  • @t.niese - the link you shared is something different. Those locking doesn't lock a row for reading. I want to lock read, means the row my one connection is processing should not be read by other connection.

    – Irfan DANISH
    Nov 19 '18 at 10:43











  • If you use FOR UPDATE then Other transactions are blocked from updating those rows, from doing SELECT ... FOR SHARE, or from reading the data in certain transaction isolation levels.. So if your isolation level is set up correctly then you can't have two transactions having a SELECT .. FOR UPDATE on the same row. So either the second transaction fails, or waits until the first FOR UPDATE finished.

    – t.niese
    Nov 19 '18 at 12:25





















  • If you use the received data in follow-up select, insert or update then you have to use FOR UPDATE or FOR SHARE within the transaction.

    – t.niese
    Nov 19 '18 at 10:06













  • Possible duplicate of Locking a row in a MYSQL table during a transaction

    – t.niese
    Nov 19 '18 at 10:10











  • How to properly use transactions and locks to ensure database integrity?

    – t.niese
    Nov 19 '18 at 10:10











  • @t.niese - the link you shared is something different. Those locking doesn't lock a row for reading. I want to lock read, means the row my one connection is processing should not be read by other connection.

    – Irfan DANISH
    Nov 19 '18 at 10:43











  • If you use FOR UPDATE then Other transactions are blocked from updating those rows, from doing SELECT ... FOR SHARE, or from reading the data in certain transaction isolation levels.. So if your isolation level is set up correctly then you can't have two transactions having a SELECT .. FOR UPDATE on the same row. So either the second transaction fails, or waits until the first FOR UPDATE finished.

    – t.niese
    Nov 19 '18 at 12:25



















If you use the received data in follow-up select, insert or update then you have to use FOR UPDATE or FOR SHARE within the transaction.

– t.niese
Nov 19 '18 at 10:06







If you use the received data in follow-up select, insert or update then you have to use FOR UPDATE or FOR SHARE within the transaction.

– t.niese
Nov 19 '18 at 10:06















Possible duplicate of Locking a row in a MYSQL table during a transaction

– t.niese
Nov 19 '18 at 10:10





Possible duplicate of Locking a row in a MYSQL table during a transaction

– t.niese
Nov 19 '18 at 10:10













How to properly use transactions and locks to ensure database integrity?

– t.niese
Nov 19 '18 at 10:10





How to properly use transactions and locks to ensure database integrity?

– t.niese
Nov 19 '18 at 10:10













@t.niese - the link you shared is something different. Those locking doesn't lock a row for reading. I want to lock read, means the row my one connection is processing should not be read by other connection.

– Irfan DANISH
Nov 19 '18 at 10:43





@t.niese - the link you shared is something different. Those locking doesn't lock a row for reading. I want to lock read, means the row my one connection is processing should not be read by other connection.

– Irfan DANISH
Nov 19 '18 at 10:43













If you use FOR UPDATE then Other transactions are blocked from updating those rows, from doing SELECT ... FOR SHARE, or from reading the data in certain transaction isolation levels.. So if your isolation level is set up correctly then you can't have two transactions having a SELECT .. FOR UPDATE on the same row. So either the second transaction fails, or waits until the first FOR UPDATE finished.

– t.niese
Nov 19 '18 at 12:25







If you use FOR UPDATE then Other transactions are blocked from updating those rows, from doing SELECT ... FOR SHARE, or from reading the data in certain transaction isolation levels.. So if your isolation level is set up correctly then you can't have two transactions having a SELECT .. FOR UPDATE on the same row. So either the second transaction fails, or waits until the first FOR UPDATE finished.

– t.niese
Nov 19 '18 at 12:25














0






active

oldest

votes











Your Answer






StackExchange.ifUsing("editor", function () {
StackExchange.using("externalEditor", function () {
StackExchange.using("snippets", function () {
StackExchange.snippets.init();
});
});
}, "code-snippets");

StackExchange.ready(function() {
var channelOptions = {
tags: "".split(" "),
id: "1"
};
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: true,
noModals: true,
showLowRepImageUploadWarning: true,
reputationToPostImages: 10,
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%2fstackoverflow.com%2fquestions%2f53372245%2fmysql-lock-row-for-reading%23new-answer', 'question_page');
}
);

Post as a guest















Required, but never shown

























0






active

oldest

votes








0






active

oldest

votes









active

oldest

votes






active

oldest

votes
















draft saved

draft discarded




















































Thanks for contributing an answer to Stack Overflow!


  • 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%2fstackoverflow.com%2fquestions%2f53372245%2fmysql-lock-row-for-reading%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







-

這個網誌中的熱門文章

Tangent Lines Diagram Along Smooth Curve

圖片
7 1 I am trying to replicate a diagram and have a minimal example. I don't know how to add additional tangents between the specified points and preserve smoothness. documentclass{article} usepackage{tikz} usetikzlibrary{calc,intersections} begin{document} begin{tikzpicture} % Axes draw [->, name path=x] (-1,0) -- (11,0) node [right] {$x$}; draw [->] (0,-1) -- (0,6) node [above] {$y$}; % Origin node at (0,0) [below left] {$0$}; % Points coordinate (start) at (1,-0.8); coordinate (c1) at (3,3); coordinate (c2) at (5.5,1.5); coordinate (c3) at (8,4); coordinate (end) at (10.5,-0.8); % show the points foreach n in {start,c1,c2,c3,end} fill [black] (n) circle (2pt) node [below] {}; % join the coordinates draw [thick,name path=curve] (start) to[out=70,in=180] (c1) to[out=0,in=180]
閱讀完整內容

Yusuf al-Mu'taman ibn Hud

圖片
Main article: Taifa of Zaragoza Al-Mu'taman Ruler of Zaragoza Reign 1081–1085 Predecessor Ahmad al-Muqtadir Successor Al-Mustain II Born Zaragoza Died 1085 Full name Yusuf ibn Ahmad al-Mu'taman ibn Hūd House Banu Hud Yusuf ibn Ahmad al-Mu'taman ibn Hūd (Arabic: المؤتمن بالله يوسف إبن أحمد إبن هود ‎, al-Mutaman bi l-Lah , died c. 1085) was the third king of the Banu Hud dynasty who ruled over the Taifa of Zaragoza from 1081 to 1085. Yusuf al-Mutaman reigned during the height of power of Muslim Zaragoza , following the thriving period of his father Ahmad al-Muqtadir. He continued his father's efforts and created around him a court of intellectuals, living in the beautiful palace of Aljafería, nicknamed as "the palace of joy". Al-Mu'taman was also a scholarly king and a patron of science, philosophy and arts. As an example of a wise king, he knew astrology, philosophy, and especially mathematics, a discipline in which
閱讀完整內容

Zucchini

圖片
This article is about the vegetable. For other uses, see Zucchini (disambiguation). Zucchini (courgette) A striped and a uniform color zucchini Genus Cucurbita Species Cucurbita pepo Origin 19th century northern Italy The zucchini ( / z uː ˈ k iː n i / , American English) or courgette ( / k ʊər ˈ ʒ ɛ t / , British English) is a summer squash which can reach nearly 1 metre (100 cm; 39 in) in length, but is usually harvested when still immature at about 15 to 25 cm (6 to 10 in). [1] A zucchini is a thin-skinned cultivar of what in Britain and Ireland is referred to as a marrow. [2] [3] In South Africa, a zucchini is known as a baby marrow. Along with certain other squashes and pumpkins, the zucchini belongs to the species Cucurbita pepo . It can be dark or light green. A related hybrid, the golden zucchini, is a deep yellow or orange color. [4] In a culinary context, the zucchini is treated as a vegetable; it is usually cooked and presented as a savory dish o
閱讀完整內容