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Solutions to the Lost Update Problem
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<p>The <strong>Lost Update Problem</strong> is a common issue in concurrent systems, where two transactions read the same data, modify it, and write it back to the database. The second transaction will overwrite the changes made by the first transaction, causing the first transaction’s changes to be lost.</p>
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<p>This is especially problematic in cases where money in a bank account is involved, as it can lead to inconsistencies in the account balance. A rather dramatic example of this is the <a href="https://www.reuters.com/article/technology/bitcoin-bank-flexcoin-shuts-after-hacking-theft-idUSBREA2329B/">Flexcoin bankruptcy</a>. </p>
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<p>For example, in MySQL the default isolation level is <code>REPEATABLE READ</code>, which means that a transaction will read the same data multiple times and get the same result. However, this does not prevent the Lost Update Problem, as shown in this sequence diagram:</p>
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<img src='data:image/svg+xml;base64,<svg xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink" version="1.1" data-diagram-type="SEQUENCE" style="width:1087px;height:614px;background:#FFFFFF;" width="1087px" height="614px" viewBox="0 0 1087 614" zoomAndPan="magnify" preserveAspectRatio="none" contentStyleType="text/css"><?plantuml 1.2026.8beta1?><defs/><g font-family="sans-serif" lengthAdjust="spacing"><g><title>Alice</title><rect x="54.221" y="41.297" width="8" height="530.922" fill="#000" fill-opacity="0"/><line x1="57.721" y1="41.297" x2="57.721" y2="572.219" style="stroke:#181818;stroke-width:0.5;stroke-dasharray:5,5;"/></g><g><title>DB</title><rect x="434.597" y="41.297" width="8" height="530.922" fill="#000" fill-opacity="0"/><line x1="438.097" y1="41.297" x2="438.097" y2="572.219" style="stroke:#181818;stroke-width:0.5;stroke-dasharray:5,5;"/></g><g><title>Bob</title><rect x="814.974" y="41.297" width="8" height="530.922" fill="#000" 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textLength="33.667">Alice</text><rect x="420.905" y="572.219" width="34.385" height="30.297" fill="#E2E2F0" style="stroke:#181818;stroke-width:0.5;" rx="2.5" ry="2.5"/><text x="427.905" y="592.214" fill="#000" font-size="14" textLength="20.385">DB</text><rect x="797.945" y="572.219" width="41.057" height="30.297" fill="#E2E2F0" style="stroke:#181818;stroke-width:0.5;" rx="2.5" ry="2.5"/><text x="804.945" y="592.214" fill="#000" font-size="14" textLength="27.057">Bob</text><polygon points="426.097,81.563,436.097,85.563,426.097,89.563,430.097,85.563" fill="#181818" style="stroke:#181818;stroke-width:1;stroke-linejoin:miter;stroke-miterlimit:10;"/><line x1="57.721" y1="85.563" x2="432.097" y2="85.563" style="stroke:#181818;stroke-width:1;"/><text x="64.721" y="65.364" fill="#000" font-size="13" textLength="356.376">set session transaction isolation level repeatable read;</text><text x="64.721" y="80.497" fill="#000" font-size="13" textLength="40.733">begin;</text><polygon points="449.097,125.828,439.097,129.828,449.097,133.828,445.097,129.828" fill="#181818" style="stroke:#181818;stroke-width:1;stroke-linejoin:miter;stroke-miterlimit:10;"/><line x1="443.097" y1="129.828" x2="817.474" y2="129.828" style="stroke:#181818;stroke-width:1;"/><text x="455.097" y="109.629" fill="#000" font-size="13" textLength="356.376">set session transaction isolation level repeatable read;</text><text x="455.097" y="124.762" fill="#000" font-size="13" textLength="40.733">begin;</text><polygon points="426.097,154.961,436.097,158.961,426.097,162.961,430.097,158.961" fill="#181818" style="stroke:#181818;stroke-width:1;stroke-linejoin:miter;stroke-miterlimit:10;"/><line x1="57.721" y1="158.961" x2="432.097" y2="158.961" style="stroke:#181818;stroke-width:1;"/><text x="64.721" y="153.895" fill="#000" font-size="13" textLength="214.583">select * from entry where id = 1;</text><path d="M15,171.961 L15,230.961 L100,230.961 L100,181.961 L90,171.961 L15,171.961" style="stroke:#181818;stroke-width:0.5;" fill="#FEFFDD"/><path d="M90,171.961 L90,181.961 L100,181.961 L90,171.961" style="stroke:#181818;stroke-width:0.5;" fill="#FEFFDD"/><text x="21" y="189.028" fill="#000" font-size="13" textLength="45.132">Result:</text><text x="25.132" y="206.161" fill="#000" font-size="13" textLength="11.864">id</text><text x="45.8" y="206.161" fill="#000" font-size="13" textLength="35.509">value</text><text x="29.265" y="221.293" fill="#000" font-size="13">1</text><text x="45.8" y="221.293" fill="#000" font-size="13" textLength="16.542">10</text><line x1="21" y1="194.094" x2="85.441" y2="194.094" style="stroke:#000;stroke-width:0.5;"/><line x1="21" y1="209.227" x2="85.441" y2="209.227" style="stroke:#000;stroke-width:0.5;"/><line x1="21" y1="224.359" x2="85.441" y2="224.359" style="stroke:#000;stroke-width:0.5;"/><line x1="21" y1="194.094" x2="21" y2="224.359" style="stroke:#000;stroke-width:0.5;"/><line x1="41.668" y1="194.094" x2="41.668" y2="224.359" style="stroke:#000;stroke-width:0.5;"/><line x1="85.441" y1="194.094" x2="85.441" y2="224.359" style="stroke:#000;stroke-width:0.5;"/><polygon points="426.097,268.625,436.097,272.625,426.097,276.625,430.097,272.625" fill="#181818" style="stroke:#181818;stroke-width:1;stroke-linejoin:miter;stroke-miterlimit:10;"/><line x1="57.721" y1="272.625" x2="432.097" y2="272.625" style="stroke:#181818;stroke-width:1;"/><text x="64.721" y="252.426" fill="#000" font-size="13" textLength="315.993">update entry set value = value - 5 where id = 1;</text><text x="64.721" y="267.559" fill="#000" font-size="13" textLength="53.517">commit;</text><path d="M15,285.625 L15,344.625 L100,344.625 L100,295.625 L90,285.625 L15,285.625" style="stroke:#181818;stroke-width:0.5;" fill="#FEFFDD"/><path d="M90,285.625 L90,295.625 L100,295.625 L90,285.625" style="stroke:#181818;stroke-width:0.5;" fill="#FEFFDD"/><text x="21" y="302.692" fill="#000" font-size="13" textLength="45.132">Result:</text><text x="25.132" 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style="stroke:#181818;stroke-width:1;stroke-linejoin:miter;stroke-miterlimit:10;"/><line x1="443.097" y1="371.156" x2="817.474" y2="371.156" style="stroke:#181818;stroke-width:1;"/><text x="455.097" y="366.09" fill="#000" font-size="13" textLength="214.583">select * from entry where id = 1;</text><path d="M565.322,384.156 L565.322,443.156 L1071.322,443.156 L1071.322,394.156 L1061.322,384.156 L565.322,384.156" style="stroke:#181818;stroke-width:0.5;" fill="#FEFFDD"/><path d="M1061.322,384.156 L1061.322,394.156 L1071.322,394.156 L1061.322,384.156" style="stroke:#181818;stroke-width:0.5;" fill="#FEFFDD"/><text x="571.322" y="401.223" fill="#000" font-size="13" textLength="485.304">Bob still sees the initial value, since he is isolated from Alice's transaction:</text><text x="575.454" y="418.356" fill="#000" font-size="13" textLength="11.864">id</text><text x="596.122" y="418.356" fill="#000" font-size="13" textLength="35.509">value</text><text x="579.586" y="433.489" fill="#000" font-size="13">1</text><text x="596.122" y="433.489" fill="#000" font-size="13" textLength="16.542">10</text><line x1="571.322" y1="406.289" x2="635.763" y2="406.289" style="stroke:#000;stroke-width:0.5;"/><line x1="571.322" y1="421.422" x2="635.763" y2="421.422" style="stroke:#000;stroke-width:0.5;"/><line x1="571.322" y1="436.555" x2="635.763" y2="436.555" style="stroke:#000;stroke-width:0.5;"/><line x1="571.322" y1="406.289" x2="571.322" y2="436.555" style="stroke:#000;stroke-width:0.5;"/><line x1="591.99" y1="406.289" x2="591.99" y2="436.555" style="stroke:#000;stroke-width:0.5;"/><line x1="635.763" y1="406.289" x2="635.763" y2="436.555" style="stroke:#000;stroke-width:0.5;"/><polygon points="449.097,480.82,439.097,484.82,449.097,488.82,445.097,484.82" fill="#181818" style="stroke:#181818;stroke-width:1;stroke-linejoin:miter;stroke-miterlimit:10;"/><line x1="443.097" y1="484.82" x2="817.474" y2="484.82" style="stroke:#181818;stroke-width:1;"/><text x="455.097" y="464.622" fill="#000" font-size="13" textLength="324.264">update entry set value = value - 10 where id = 1;</text><text x="455.097" y="479.754" fill="#000" font-size="13" textLength="53.517">commit;</text><path d="M705.903,497.82 L705.903,556.82 L930.903,556.82 L930.903,507.82 L920.903,497.82 L705.903,497.82" style="stroke:#181818;stroke-width:0.5;" fill="#FEFFDD"/><path d="M920.903,497.82 L920.903,507.82 L930.903,507.82 L920.903,497.82" style="stroke:#181818;stroke-width:0.5;" fill="#FEFFDD"/><text x="711.903" y="514.887" fill="#000" font-size="13" textLength="204.141">Bob overwrote Alice's changes:</text><text x="716.036" y="532.02" fill="#000" font-size="13" textLength="11.864">id</text><text x="736.704" y="532.02" fill="#000" font-size="13" textLength="35.509">value</text><text x="720.168" y="547.153" fill="#000" font-size="13">1</text><text x="736.704" y="547.153" fill="#000" font-size="13">0</text><line x1="711.903" y1="519.953" x2="776.345" y2="519.953" 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<p>Fortunately, there are several ways to solve the Lost Update Problem:</p>
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<h2 id="Isolation-Level-SERIALIZABLE"><a href="#Isolation-Level-SERIALIZABLE" class="headerlink" title="Isolation Level SERIALIZABLE"></a>Isolation Level <code>SERIALIZABLE</code></h2><p><code>SERIALIZABLE</code> is the strictest isolation level, which prevents the Lost Update Problem by bailing out transactions that would cause conflicts:</p>
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<img src='data:image/svg+xml;base64,<svg xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink" version="1.1" data-diagram-type="SEQUENCE" style="width:1253px;height:427px;background:#FFFFFF;" width="1253px" height="427px" viewBox="0 0 1253 427" zoomAndPan="magnify" preserveAspectRatio="none" contentStyleType="text/css"><?plantuml 1.2026.8beta1?><defs/><g font-family="sans-serif" lengthAdjust="spacing"><g><title>Alice</title><rect x="201.131" y="41.297" width="8" height="343.594" fill="#000" fill-opacity="0"/><line x1="204.631" y1="41.297" x2="204.631" y2="384.891" style="stroke:#181818;stroke-width:0.5;stroke-dasharray:5,5;"/></g><g><title>DB</title><rect x="550.899" y="41.297" width="8" height="343.594" fill="#000" fill-opacity="0"/><line x1="554.399" y1="41.297" x2="554.399" y2="384.891" style="stroke:#181818;stroke-width:0.5;stroke-dasharray:5,5;"/></g><g><title>Bob</title><rect x="900.667" y="41.297" width="8" height="343.594" fill="#000" fill-opacity="0"/><line x1="904.167" y1="41.297" x2="904.167" y2="384.891" style="stroke:#181818;stroke-width:0.5;stroke-dasharray:5,5;"/></g><rect x="180.797" y="10" width="47.667" height="30.297" fill="#E2E2F0" style="stroke:#181818;stroke-width:0.5;" rx="2.5" ry="2.5"/><text x="187.797" y="29.995" fill="#000" font-size="14" textLength="33.667">Alice</text><rect x="537.207" y="10" width="34.385" height="30.297" fill="#E2E2F0" style="stroke:#181818;stroke-width:0.5;" rx="2.5" ry="2.5"/><text x="544.207" y="29.995" fill="#000" font-size="14" textLength="20.385">DB</text><rect x="883.639" y="10" width="41.057" height="30.297" fill="#E2E2F0" style="stroke:#181818;stroke-width:0.5;" rx="2.5" ry="2.5"/><text x="890.639" y="29.995" fill="#000" font-size="14" textLength="27.057">Bob</text><rect x="180.797" y="384.891" width="47.667" height="30.297" fill="#E2E2F0" style="stroke:#181818;stroke-width:0.5;" rx="2.5" ry="2.5"/><text x="187.797" y="404.886" fill="#000" font-size="14" textLength="33.667">Alice</text><rect x="537.207" y="384.891" width="34.385" height="30.297" fill="#E2E2F0" style="stroke:#181818;stroke-width:0.5;" rx="2.5" ry="2.5"/><text x="544.207" y="404.886" fill="#000" font-size="14" textLength="20.385">DB</text><rect x="883.639" y="384.891" width="41.057" height="30.297" fill="#E2E2F0" style="stroke:#181818;stroke-width:0.5;" rx="2.5" ry="2.5"/><text x="890.639" y="404.886" fill="#000" font-size="14" textLength="27.057">Bob</text><polygon points="542.399,81.563,552.399,85.563,542.399,89.563,546.399,85.563" fill="#181818" style="stroke:#181818;stroke-width:1;stroke-linejoin:miter;stroke-miterlimit:10;"/><line x1="204.631" y1="85.563" x2="548.399" y2="85.563" style="stroke:#181818;stroke-width:1;"/><text x="211.631" y="65.364" fill="#000" font-size="13" textLength="325.768">set session transaction isolation level serializable;</text><text x="211.631" y="80.497" fill="#000" font-size="13" textLength="40.733">begin;</text><polygon points="565.399,125.828,555.399,129.828,565.399,133.828,561.399,129.828" fill="#181818" style="stroke:#181818;stroke-width:1;stroke-linejoin:miter;stroke-miterlimit:10;"/><line x1="559.399" y1="129.828" x2="903.167" y2="129.828" style="stroke:#181818;stroke-width:1;"/><text x="571.399" y="109.629" fill="#000" font-size="13" textLength="325.768">set session transaction isolation level serializable;</text><text x="571.399" y="124.762" fill="#000" font-size="13" textLength="40.733">begin;</text><polygon points="542.399,154.961,552.399,158.961,542.399,162.961,546.399,158.961" fill="#181818" style="stroke:#181818;stroke-width:1;stroke-linejoin:miter;stroke-miterlimit:10;"/><line x1="204.631" y1="158.961" x2="548.399" y2="158.961" style="stroke:#181818;stroke-width:1;"/><text x="211.631" y="153.895" fill="#000" font-size="13" textLength="214.583">select * from entry where id = 1;</text><path d="M15,171.961 L15,211.961 L394,211.961 L394,181.961 L384,171.961 L15,171.961" style="stroke:#181818;stroke-width:0.5;" fill="#FEFFDD"/><path d="M384,171.961 L384,181.961 L394,181.961 L384,171.961" style="stroke:#181818;stroke-width:0.5;" fill="#FEFFDD"/><text x="21" y="189.028" fill="#000" font-size="13" textLength="358.262">Alice's transaction now holds a shared lock on the row.</text><text x="21" y="204.161" fill="#000" font-size="13" textLength="269.058">It's the same as `SELECT ... FOR SHARE`.</text><polygon points="565.399,234.359,555.399,238.359,565.399,242.359,561.399,238.359" fill="#181818" style="stroke:#181818;stroke-width:1;stroke-linejoin:miter;stroke-miterlimit:10;"/><line x1="559.399" y1="238.359" x2="903.167" y2="238.359" style="stroke:#181818;stroke-width:1;"/><text x="571.399" y="233.293" fill="#000" font-size="13" textLength="214.583">select * from entry where id = 1;</text><path d="M821.685,251.359 L821.685,276.359 L985.685,276.359 L985.685,261.359 L975.685,251.359 L821.685,251.359" style="stroke:#181818;stroke-width:0.5;" fill="#FEFFDD"/><path d="M975.685,251.359 L975.685,261.359 L985.685,261.359 L975.685,251.359" style="stroke:#181818;stroke-width:0.5;" fill="#FEFFDD"/><text x="827.685" y="268.426" fill="#000" font-size="13" textLength="143.965">Bob can read the row.</text><polygon points="542.399,298.625,552.399,302.625,542.399,306.625,546.399,302.625" fill="#181818" style="stroke:#181818;stroke-width:1;stroke-linejoin:miter;stroke-miterlimit:10;"/><line x1="204.631" y1="302.625" x2="548.399" y2="302.625" style="stroke:#181818;stroke-width:1;"/><text x="211.631" y="297.559" fill="#000" font-size="13" textLength="282.617">update entry set value = 'T1' where id = 1;</text><polygon points="565.399,327.758,555.399,331.758,565.399,335.758,561.399,331.758" fill="#181818" style="stroke:#181818;stroke-width:1;stroke-linejoin:miter;stroke-miterlimit:10;"/><line x1="559.399" y1="331.758" x2="903.167" y2="331.758" style="stroke:#181818;stroke-width:1;"/><text x="571.399" y="326.692" fill="#000" font-size="13" textLength="282.617">update entry set value = 'T2' where id = 1;</text><path d="M570.375,344.758 L570.375,369.758 L1237.375,369.758 L1237.375,354.758 L1227.375,344.758 L570.375,344.758" style="stroke:#181818;stroke-width:0.5;" fill="#FEFFDD"/><path d="M1227.375,344.758 L1227.375,354.758 L1237.375,354.758 L1227.375,344.758" style="stroke:#181818;stroke-width:0.5;" fill="#FEFFDD"/><text x="576.375" y="361.825" fill="#000" font-size="13" textLength="646.585">Bob get' an error: [40001][1213] Deadlock found when trying to get lock; try restarting transaction</text><?plantuml-src hP5FQm8n4CNl-odURQ7GnRKzkRIWrT92eQ3UhE2uExgXCIb9NB6VlfCLQlKWBVGGCldptlncfgzLoRY-nt207Zm7MTuhQn0S6KzbYB7oLbCRQMvOon-dIAjFMcektioIryeKoS0k_ycfVqQbkGoumihP3TW4jyUkPiTG5UwG5qbYR63OXXrQQOB3dlgJvCRkK5jTUH1yJOuhQ5k-8pBM36TtcIYVGvJ9sTE6GHwBoUXbz315bcLuV1rZyjGVZnPPmgP2J9oSLVu7MX5AnYWloS0nLKUIe_rfExOV5Od-u1pxt93UibYdqpmzJ_MJx8Amc_w6SSqXXN2oSzRrCBljT3hvV9PtyvivXWBVTdDbjq8kTd7oUsNM23PAsruNyKuAzO5SQD-Ey_ck-0i0?></g></svg>'>
|
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<p>In MySQL, <code>SERIALIZABLE</code> is the same as <code>SELECT ... FOR SHARE</code>, which means reads are not blocked, but writes are. This can lead to deadlocks, as shown in the sequence diagram above.</p>
|
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<h2 id="SELECT-…-FOR-UPDATE"><a href="#SELECT-…-FOR-UPDATE" class="headerlink" title="SELECT … FOR UPDATE"></a>SELECT … FOR UPDATE</h2><p><code>SELECT ... FOR UPDATE</code> is a way to lock rows for writing, which prevents other transactions from reading or writing the same rows. This is useful when you want to prevent the Lost Update Problem, but do not want to use the <code>SERIALIZABLE</code> isolation level:</p>
|
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<img src='data:image/svg+xml;base64,<svg xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink" version="1.1" data-diagram-type="SEQUENCE" style="width:1207px;height:639px;background:#FFFFFF;" width="1207px" height="639px" viewBox="0 0 1207 639" zoomAndPan="magnify" preserveAspectRatio="none" contentStyleType="text/css"><?plantuml 1.2026.8beta1?><defs/><g font-family="sans-serif" lengthAdjust="spacing"><g><title>Alice</title><rect x="234.685" y="41.297" width="8" height="556.055" fill="#000" fill-opacity="0"/><line x1="238.185" y1="41.297" x2="238.185" y2="597.352" style="stroke:#181818;stroke-width:0.5;stroke-dasharray:5,5;"/></g><g><title>DB</title><rect x="574.677" y="41.297" width="8" height="556.055" fill="#000" fill-opacity="0"/><line x1="578.177" y1="41.297" x2="578.177" y2="597.352" style="stroke:#181818;stroke-width:0.5;stroke-dasharray:5,5;"/></g><g><title>Bob</title><rect x="914.67" y="41.297" width="8" height="556.055" fill="#000" fill-opacity="0"/><line x1="918.17" y1="41.297" x2="918.17" y2="597.352" style="stroke:#181818;stroke-width:0.5;stroke-dasharray:5,5;"/></g><rect x="214.351" y="10" width="47.667" height="30.297" fill="#E2E2F0" style="stroke:#181818;stroke-width:0.5;" rx="2.5" ry="2.5"/><text x="221.351" y="29.995" fill="#000" font-size="14" textLength="33.667">Alice</text><rect x="560.985" y="10" width="34.385" height="30.297" fill="#E2E2F0" style="stroke:#181818;stroke-width:0.5;" rx="2.5" ry="2.5"/><text x="567.985" y="29.995" fill="#000" font-size="14" textLength="20.385">DB</text><rect x="897.642" y="10" width="41.057" height="30.297" fill="#E2E2F0" style="stroke:#181818;stroke-width:0.5;" rx="2.5" ry="2.5"/><text x="904.642" y="29.995" fill="#000" font-size="14" textLength="27.057">Bob</text><rect x="214.351" y="597.352" width="47.667" height="30.297" fill="#E2E2F0" style="stroke:#181818;stroke-width:0.5;" rx="2.5" ry="2.5"/><text x="221.351" y="617.347" fill="#000" font-size="14" textLength="33.667">Alice</text><rect x="560.985" y="597.352" width="34.385" height="30.297" fill="#E2E2F0" style="stroke:#181818;stroke-width:0.5;" rx="2.5" ry="2.5"/><text x="567.985" y="617.347" fill="#000" font-size="14" textLength="20.385">DB</text><rect x="897.642" y="597.352" width="41.057" height="30.297" fill="#E2E2F0" style="stroke:#181818;stroke-width:0.5;" rx="2.5" ry="2.5"/><text x="904.642" y="617.347" fill="#000" font-size="14" textLength="27.057">Bob</text><polygon points="566.177,81.563,576.177,85.563,566.177,89.563,570.177,85.563" fill="#181818" style="stroke:#181818;stroke-width:1;stroke-linejoin:miter;stroke-miterlimit:10;"/><line x1="238.185" y1="85.563" x2="572.177" y2="85.563" style="stroke:#181818;stroke-width:1;"/><text x="245.185" y="65.364" fill="#000" font-size="13"> </text><text x="245.185" y="80.497" fill="#000" font-size="13" textLength="40.733">begin;</text><polygon points="589.177,110.695,579.177,114.695,589.177,118.695,585.177,114.695" fill="#181818" style="stroke:#181818;stroke-width:1;stroke-linejoin:miter;stroke-miterlimit:10;"/><line x1="583.177" y1="114.695" x2="917.17" y2="114.695" style="stroke:#181818;stroke-width:1;"/><text x="595.177" y="109.629" fill="#000" font-size="13" textLength="64.733">set begin;</text><polygon points="566.177,139.828,576.177,143.828,566.177,147.828,570.177,143.828" fill="#181818" style="stroke:#181818;stroke-width:1;stroke-linejoin:miter;stroke-miterlimit:10;"/><line x1="238.185" y1="143.828" x2="572.177" y2="143.828" style="stroke:#181818;stroke-width:1;"/><text x="245.185" y="138.762" fill="#000" font-size="13" textLength="286.527">select * from entry where id = 1 for update;</text><path d="M195.464,156.828 L195.464,215.828 L280.464,215.828 L280.464,166.828 L270.464,156.828 L195.464,156.828" style="stroke:#181818;stroke-width:0.5;" fill="#FEFFDD"/><path d="M270.464,156.828 L270.464,166.828 L280.464,166.828 L270.464,156.828" style="stroke:#181818;stroke-width:0.5;" fill="#FEFFDD"/><text x="201.464" y="173.895" fill="#000" font-size="13" textLength="45.132">Result:</text><text x="205.596" y="191.028" fill="#000" font-size="13" textLength="11.864">id</text><text x="226.264" y="191.028" fill="#000" font-size="13" textLength="35.509">value</text><text x="209.729" y="206.161" fill="#000" font-size="13">1</text><text x="226.264" y="206.161" fill="#000" font-size="13" textLength="16.542">10</text><line x1="201.464" y1="178.961" x2="265.905" y2="178.961" style="stroke:#000;stroke-width:0.5;"/><line x1="201.464" y1="194.094" x2="265.905" y2="194.094" style="stroke:#000;stroke-width:0.5;"/><line x1="201.464" y1="209.227" x2="265.905" y2="209.227" style="stroke:#000;stroke-width:0.5;"/><line x1="201.464" y1="178.961" x2="201.464" y2="209.227" style="stroke:#000;stroke-width:0.5;"/><line x1="222.132" y1="178.961" x2="222.132" y2="209.227" style="stroke:#000;stroke-width:0.5;"/><line x1="265.905" y1="178.961" x2="265.905" y2="209.227" style="stroke:#000;stroke-width:0.5;"/><polygon points="589.177,238.359,579.177,242.359,589.177,246.359,585.177,242.359" fill="#181818" style="stroke:#181818;stroke-width:1;stroke-linejoin:miter;stroke-miterlimit:10;"/><line x1="583.177" y1="242.359" x2="917.17" y2="242.359" style="stroke:#181818;stroke-width:1;"/><text x="595.177" y="237.293" fill="#000" font-size="13" textLength="286.527">select * from entry where id = 1 for update;</text><path d="M645.02,255.359 L645.02,280.359 L1191.02,280.359 L1191.02,265.359 L1181.02,255.359 L645.02,255.359" style="stroke:#181818;stroke-width:0.5;" fill="#FEFFDD"/><path d="M1181.02,255.359 L1181.02,265.359 L1191.02,265.359 L1181.02,255.359" style="stroke:#181818;stroke-width:0.5;" fill="#FEFFDD"/><text x="651.02" y="272.426" fill="#000" font-size="13" textLength="525.3">Bob's transaction is blocked until Alice's transaction is committed or rolled back.</text><polygon points="566.177,302.625,576.177,306.625,566.177,310.625,570.177,306.625" fill="#181818" style="stroke:#181818;stroke-width:1;stroke-linejoin:miter;stroke-miterlimit:10;"/><line x1="238.185" y1="306.625" x2="572.177" y2="306.625" style="stroke:#181818;stroke-width:1;"/><text x="245.185" y="301.559" fill="#000" font-size="13" textLength="315.993">update entry set value = value - 5 where id = 1;</text><polygon points="566.177,331.758,576.177,335.758,566.177,339.758,570.177,335.758" fill="#181818" style="stroke:#181818;stroke-width:1;stroke-linejoin:miter;stroke-miterlimit:10;"/><line x1="238.185" y1="335.758" x2="572.177" y2="335.758" style="stroke:#181818;stroke-width:1;"/><text x="245.185" y="330.692" fill="#000" font-size="13" textLength="53.517">commit;</text><path d="M15,348.758 L15,452.758 L461,452.758 L461,358.758 L451,348.758 L15,348.758" style="stroke:#181818;stroke-width:0.5;" fill="#FEFFDD"/><path d="M451,348.758 L451,358.758 L461,358.758 L451,348.758" style="stroke:#181818;stroke-width:0.5;" fill="#FEFFDD"/><text x="21" y="365.825" fill="#000" font-size="13" textLength="45.132">Result:</text><text x="25.132" y="382.958" fill="#000" font-size="13" textLength="11.864">id</text><text x="45.8" y="382.958" fill="#000" font-size="13" textLength="35.509">value</text><text x="29.265" y="398.09" fill="#000" font-size="13">1</text><text x="45.8" y="398.09" fill="#000" font-size="13">5</text><line x1="21" y1="370.891" x2="85.441" y2="370.891" style="stroke:#000;stroke-width:0.5;"/><line x1="21" y1="386.023" x2="85.441" y2="386.023" style="stroke:#000;stroke-width:0.5;"/><line x1="21" y1="401.156" x2="85.441" y2="401.156" style="stroke:#000;stroke-width:0.5;"/><line x1="21" y1="370.891" x2="21" y2="401.156" style="stroke:#000;stroke-width:0.5;"/><line x1="41.668" y1="370.891" x2="41.668" y2="401.156" style="stroke:#000;stroke-width:0.5;"/><line x1="85.441" y1="370.891" x2="85.441" y2="401.156" style="stroke:#000;stroke-width:0.5;"/><text x="21" y="415.223" fill="#000" font-size="13"> </text><text x="21" y="430.356" fill="#000" font-size="13" textLength="425.369">Bob's transaction is unblocked. He get's the same result as Alice.</text><text x="21" y="445.489" fill="#000" font-size="13"> </text><polygon points="589.177,475.688,579.177,479.688,589.177,483.688,585.177,479.688" fill="#181818" style="stroke:#181818;stroke-width:1;stroke-linejoin:miter;stroke-miterlimit:10;"/><line x1="583.177" y1="479.688" x2="917.17" y2="479.688" style="stroke:#181818;stroke-width:1;"/><text x="595.177" y="474.622" fill="#000" font-size="13" textLength="315.993">update entry set value = value - 5 where id = 1;</text><path d="M809.132,492.688 L809.132,581.688 L1027.132,581.688 L1027.132,502.688 L1017.132,492.688 L809.132,492.688" style="stroke:#181818;stroke-width:0.5;" fill="#FEFFDD"/><path d="M1017.132,492.688 L1017.132,502.688 L1027.132,502.688 L1017.132,492.688" style="stroke:#181818;stroke-width:0.5;" fill="#FEFFDD"/><text x="815.132" y="509.754" fill="#000" font-size="13" textLength="197.076">Bob's transaction is commited</text><text x="815.132" y="524.887" fill="#000" font-size="13"> </text><text x="815.132" y="540.02" fill="#000" font-size="13" textLength="45.132">Result:</text><text x="819.264" y="557.153" fill="#000" font-size="13" textLength="11.864">id</text><text x="839.932" y="557.153" fill="#000" font-size="13" textLength="35.509">value</text><text x="823.397" y="572.286" fill="#000" font-size="13">1</text><text x="839.932" y="572.286" fill="#000" font-size="13">0</text><line x1="815.132" y1="545.086" x2="879.573" y2="545.086" style="stroke:#000;stroke-width:0.5;"/><line x1="815.132" y1="560.219" x2="879.573" y2="560.219" style="stroke:#000;stroke-width:0.5;"/><line x1="815.132" y1="575.352" x2="879.573" y2="575.352" style="stroke:#000;stroke-width:0.5;"/><line x1="815.132" y1="545.086" x2="815.132" y2="575.352" style="stroke:#000;stroke-width:0.5;"/><line x1="835.8" y1="545.086" x2="835.8" y2="575.352" style="stroke:#000;stroke-width:0.5;"/><line x1="879.573" y1="545.086" x2="879.573" y2="575.352" style="stroke:#000;stroke-width:0.5;"/><?plantuml-src dL8zQyCm4DtrAzvM2CGaGvQO518wTEwSHPOlYOWi5UcKKl2FhsIvfKuRIAj17yUxk_VUQMkq8imVyRJ36dlRq57RMknSynKCn1Z3smawa275cE7WNGUoxD_nTY9Fq2qsMEBWFE9hAvbg8QnZWhkGnr15l528XjUYp-WU5saYeK_FbDXZkK1UlI3R8gUAAqx_Qvrg2EJz8O2zj44griv21pJ6gJErY9QrAHn_WfJhEisSOAc-TyQaMoFLkVh6SsfI8J5Ip5OMePlnd6Cr8LvVvvUEl_W7V3gOR9fwc0E3YwlYuIt9qOwYApmJZiGPSY84sH7yK1qob7wLk36AlmkyQnn5DxNYBg6BwMVv0000?></g></svg>'>
|
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<h2 id="Optimistic-Locking"><a href="#Optimistic-Locking" class="headerlink" title="Optimistic Locking"></a>Optimistic Locking</h2><p>This approach involves adding a version column to the table, which is incremented every time a row is updated. When a transaction updates a row, it checks whether the version has changed since it was read. If the version has changed, the transaction will fail and the changes will not be applied. This approach is useful when conflicts are rare, as it avoids the overhead of locking and blocking transactions:</p>
|
||
<img src='data:image/svg+xml;base64,<svg xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink" version="1.1" data-diagram-type="SEQUENCE" style="width:1434px;height:421px;background:#FFFFFF;" width="1434px" height="421px" viewBox="0 0 1434 421" zoomAndPan="magnify" preserveAspectRatio="none" contentStyleType="text/css"><?plantuml 1.2026.8beta1?><defs/><g font-family="sans-serif" lengthAdjust="spacing"><g><title>Alice</title><rect x="82.16" y="41.297" width="8" height="337.594" fill="#000" fill-opacity="0"/><line x1="85.66" y1="41.297" x2="85.66" y2="378.891" style="stroke:#181818;stroke-width:0.5;stroke-dasharray:5,5;"/></g><g><title>DB</title><rect x="613.223" y="41.297" width="8" height="337.594" fill="#000" fill-opacity="0"/><line x1="616.723" y1="41.297" x2="616.723" y2="378.891" style="stroke:#181818;stroke-width:0.5;stroke-dasharray:5,5;"/></g><g><title>Bob</title><rect x="1152.558" y="41.297" width="8" height="337.594" fill="#000" fill-opacity="0"/><line x1="1156.058" y1="41.297" x2="1156.058" y2="378.891" style="stroke:#181818;stroke-width:0.5;stroke-dasharray:5,5;"/></g><rect x="61.826" y="10" width="47.667" height="30.297" fill="#E2E2F0" style="stroke:#181818;stroke-width:0.5;" rx="2.5" ry="2.5"/><text x="68.826" y="29.995" fill="#000" font-size="14" textLength="33.667">Alice</text><rect x="599.531" y="10" width="34.385" height="30.297" fill="#E2E2F0" style="stroke:#181818;stroke-width:0.5;" rx="2.5" ry="2.5"/><text x="606.531" y="29.995" fill="#000" font-size="14" textLength="20.385">DB</text><rect x="1135.53" y="10" width="41.057" height="30.297" fill="#E2E2F0" style="stroke:#181818;stroke-width:0.5;" rx="2.5" ry="2.5"/><text x="1142.53" y="29.995" fill="#000" font-size="14" textLength="27.057">Bob</text><rect x="61.826" y="378.891" width="47.667" height="30.297" fill="#E2E2F0" style="stroke:#181818;stroke-width:0.5;" rx="2.5" ry="2.5"/><text x="68.826" y="398.886" fill="#000" font-size="14" textLength="33.667">Alice</text><rect x="599.531" y="378.891" width="34.385" height="30.297" fill="#E2E2F0" style="stroke:#181818;stroke-width:0.5;" rx="2.5" ry="2.5"/><text x="606.531" y="398.886" fill="#000" font-size="14" textLength="20.385">DB</text><rect x="1135.53" y="378.891" width="41.057" height="30.297" fill="#E2E2F0" style="stroke:#181818;stroke-width:0.5;" rx="2.5" ry="2.5"/><text x="1142.53" y="398.886" fill="#000" font-size="14" textLength="27.057">Bob</text><polygon points="604.723,66.43,614.723,70.43,604.723,74.43,608.723,70.43" fill="#181818" style="stroke:#181818;stroke-width:1;stroke-linejoin:miter;stroke-miterlimit:10;"/><line x1="85.66" y1="70.43" x2="610.723" y2="70.43" style="stroke:#181818;stroke-width:1;"/><text x="92.66" y="65.364" fill="#000" font-size="13" textLength="322.347">select * from entry where id = 1 and version = 1;</text><polygon points="627.723,95.563,617.723,99.563,627.723,103.563,623.723,99.563" fill="#181818" style="stroke:#181818;stroke-width:1;stroke-linejoin:miter;stroke-miterlimit:10;"/><line x1="621.723" y1="99.563" x2="1155.058" y2="99.563" style="stroke:#181818;stroke-width:1;"/><text x="633.723" y="94.497" fill="#000" font-size="13" textLength="322.347">select * from entry where id = 1 and version = 1;</text><polygon points="604.723,124.695,614.723,128.695,604.723,132.695,608.723,128.695" fill="#181818" style="stroke:#181818;stroke-width:1;stroke-linejoin:miter;stroke-miterlimit:10;"/><line x1="85.66" y1="128.695" x2="610.723" y2="128.695" style="stroke:#181818;stroke-width:1;"/><text x="92.66" y="123.629" fill="#000" font-size="13" textLength="507.063">update entry set value = value - 5, version = 2 where id = 1 and version = 1;</text><path d="M15,141.695 L15,200.695 L156,200.695 L156,151.695 L146,141.695 L15,141.695" style="stroke:#181818;stroke-width:0.5;" fill="#FEFFDD"/><path d="M146,141.695 L146,151.695 L156,151.695 L146,141.695" style="stroke:#181818;stroke-width:0.5;" fill="#FEFFDD"/><text x="21" y="158.762" fill="#000" font-size="13" textLength="45.132">Result:</text><text x="25.132" y="175.895" fill="#000" font-size="13" textLength="11.864">id</text><text x="45.8" y="175.895" fill="#000" font-size="13" textLength="35.509">value</text><text x="89.574" y="175.895" fill="#000" font-size="13" textLength="47.614">version</text><text x="29.265" y="191.028" fill="#000" font-size="13">1</text><text x="45.8" y="191.028" fill="#000" font-size="13">5</text><text x="89.574" y="191.028" fill="#000" font-size="13">2</text><line x1="21" y1="163.828" x2="141.32" y2="163.828" style="stroke:#000;stroke-width:0.5;"/><line x1="21" y1="178.961" x2="141.32" y2="178.961" style="stroke:#000;stroke-width:0.5;"/><line x1="21" y1="194.094" x2="141.32" y2="194.094" style="stroke:#000;stroke-width:0.5;"/><line x1="21" y1="163.828" x2="21" y2="194.094" style="stroke:#000;stroke-width:0.5;"/><line x1="41.668" y1="163.828" x2="41.668" y2="194.094" style="stroke:#000;stroke-width:0.5;"/><line x1="85.441" y1="163.828" x2="85.441" y2="194.094" style="stroke:#000;stroke-width:0.5;"/><line x1="141.32" y1="163.828" x2="141.32" y2="194.094" style="stroke:#000;stroke-width:0.5;"/><polygon points="627.723,223.227,617.723,227.227,627.723,231.227,623.723,227.227" fill="#181818" style="stroke:#181818;stroke-width:1;stroke-linejoin:miter;stroke-miterlimit:10;"/><line x1="621.723" y1="227.227" x2="1155.058" y2="227.227" style="stroke:#181818;stroke-width:1;"/><text x="633.723" y="222.161" fill="#000" font-size="13" textLength="515.334">update entry set value = value - 10, version = 2 where id = 1 and version = 1;</text><path d="M893.683,240.227 L893.683,299.227 L1417.683,299.227 L1417.683,250.227 L1407.683,240.227 L893.683,240.227" style="stroke:#181818;stroke-width:0.5;" fill="#FEFFDD"/><path d="M1407.683,240.227 L1407.683,250.227 L1417.683,250.227 L1407.683,240.227" style="stroke:#181818;stroke-width:0.5;" fill="#FEFFDD"/><text x="899.683" y="257.293" fill="#000" font-size="13" textLength="503.75">Bob's transaction does not affected anything, since the version has changed:</text><text x="903.815" y="274.426" fill="#000" font-size="13" textLength="11.864">id</text><text x="924.483" y="274.426" fill="#000" font-size="13" textLength="35.509">value</text><text x="968.257" y="274.426" fill="#000" font-size="13" textLength="47.614">version</text><text x="907.948" y="289.559" fill="#000" font-size="13">1</text><text x="924.483" y="289.559" fill="#000" font-size="13">5</text><text x="968.257" y="289.559" fill="#000" font-size="13">2</text><line x1="899.683" y1="262.359" x2="1020.003" y2="262.359" style="stroke:#000;stroke-width:0.5;"/><line x1="899.683" y1="277.492" x2="1020.003" y2="277.492" style="stroke:#000;stroke-width:0.5;"/><line x1="899.683" y1="292.625" x2="1020.003" y2="292.625" style="stroke:#000;stroke-width:0.5;"/><line x1="899.683" y1="262.359" x2="899.683" y2="292.625" style="stroke:#000;stroke-width:0.5;"/><line x1="920.351" y1="262.359" x2="920.351" y2="292.625" style="stroke:#000;stroke-width:0.5;"/><line x1="964.124" y1="262.359" x2="964.124" y2="292.625" style="stroke:#000;stroke-width:0.5;"/><line x1="1020.003" y1="262.359" x2="1020.003" y2="292.625" style="stroke:#000;stroke-width:0.5;"/><polygon points="627.723,321.758,617.723,325.758,627.723,329.758,623.723,325.758" fill="#181818" style="stroke:#181818;stroke-width:1;stroke-linejoin:miter;stroke-miterlimit:10;"/><line x1="621.723" y1="325.758" x2="1155.058" y2="325.758" style="stroke:#181818;stroke-width:1;"/><text x="633.723" y="320.692" fill="#000" font-size="13" textLength="142.391">select ROW_COUNT();</text><path d="M928.344,338.758 L928.344,363.758 L1383.344,363.758 L1383.344,348.758 L1373.344,338.758 L928.344,338.758" style="stroke:#181818;stroke-width:0.5;" fill="#FEFFDD"/><path d="M1373.344,338.758 L1373.344,348.758 L1383.344,348.758 L1373.344,338.758" style="stroke:#181818;stroke-width:0.5;" fill="#FEFFDD"/><text x="934.344" y="355.825" fill="#000" font-size="13" textLength="434.427">ROW_COUNT() returns 0, since the update did not affect any rows.</text><?plantuml-src hL5BImCn4BxdLtmt7xJI2hrK55ezMoYAHucRsIQm9fB9jXJouvsqox85eQ3E8Q-Pxp6JHUCgmlW1JqlCmTHGbN2DEePFa4znZvsbI706zvX2UuCjHNR1b_kTMeQFFw3LuaI-_J8wKOTaIjZgfYKfFUvZp4O3_EqvSX-4BCWR3Z8AM1EtJPhBAHTOxeXp3yo7bB1bp50YYymniY9HA9pgfEkpfgUJNxeM5R4ZwmKZHUrPLwdKcK1SZ43NjGoSZB3iatL-Cm8xBmDDbdfMgncLrNv3vdyRxxvxlNfxVrozFhzSNltWVf15fDH6pvWCRNRZCyuCMYeD8OOTt_JQtm00?></g></svg>'>
|
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|
||
<p>As an alternative, you can use a <code>WHERE</code> clause with the old value, instead of a version column. This is useful when the table does not have a version column:</p>
|
||
<img src='data:image/svg+xml;base64,<svg xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink" version="1.1" data-diagram-type="SEQUENCE" style="width:1279px;height:520px;background:#FFFFFF;" width="1279px" height="520px" viewBox="0 0 1279 520" zoomAndPan="magnify" preserveAspectRatio="none" contentStyleType="text/css"><?plantuml 1.2026.8beta1?><defs/><g font-family="sans-serif" lengthAdjust="spacing"><g><title>Alice</title><rect x="120.747" y="41.297" width="8" height="437.258" fill="#000" fill-opacity="0"/><line x1="124.247" y1="41.297" x2="124.247" y2="478.555" style="stroke:#181818;stroke-width:0.5;stroke-dasharray:5,5;"/></g><g><title>DB</title><rect x="564.67" y="41.297" width="8" height="437.258" fill="#000" fill-opacity="0"/><line x1="568.17" y1="41.297" x2="568.17" y2="478.555" style="stroke:#181818;stroke-width:0.5;stroke-dasharray:5,5;"/></g><g><title>Bob</title><rect x="1016.864" y="41.297" width="8" height="437.258" fill="#000" fill-opacity="0"/><line x1="1020.364" y1="41.297" x2="1020.364" y2="478.555" style="stroke:#181818;stroke-width:0.5;stroke-dasharray:5,5;"/></g><rect x="100.414" y="10" width="47.667" height="30.297" fill="#E2E2F0" style="stroke:#181818;stroke-width:0.5;" rx="2.5" ry="2.5"/><text x="107.414" y="29.995" fill="#000" font-size="14" textLength="33.667">Alice</text><rect x="550.978" y="10" width="34.385" height="30.297" fill="#E2E2F0" style="stroke:#181818;stroke-width:0.5;" rx="2.5" ry="2.5"/><text x="557.978" y="29.995" fill="#000" font-size="14" textLength="20.385">DB</text><rect x="999.836" y="10" width="41.057" height="30.297" fill="#E2E2F0" style="stroke:#181818;stroke-width:0.5;" rx="2.5" ry="2.5"/><text x="1006.836" y="29.995" fill="#000" font-size="14" textLength="27.057">Bob</text><rect x="100.414" y="478.555" width="47.667" height="30.297" fill="#E2E2F0" style="stroke:#181818;stroke-width:0.5;" rx="2.5" ry="2.5"/><text x="107.414" y="498.55" fill="#000" font-size="14" textLength="33.667">Alice</text><rect x="550.978" y="478.555" width="34.385" height="30.297" fill="#E2E2F0" style="stroke:#181818;stroke-width:0.5;" rx="2.5" ry="2.5"/><text x="557.978" y="498.55" fill="#000" font-size="14" textLength="20.385">DB</text><rect x="999.836" y="478.555" width="41.057" height="30.297" fill="#E2E2F0" style="stroke:#181818;stroke-width:0.5;" rx="2.5" ry="2.5"/><text x="1006.836" y="498.55" fill="#000" font-size="14" textLength="27.057">Bob</text><polygon points="556.17,66.43,566.17,70.43,556.17,74.43,560.17,70.43" fill="#181818" style="stroke:#181818;stroke-width:1;stroke-linejoin:miter;stroke-miterlimit:10;"/><line x1="124.247" y1="70.43" x2="562.17" y2="70.43" style="stroke:#181818;stroke-width:1;"/><text x="131.247" y="65.364" fill="#000" font-size="13" textLength="214.583">select * from entry where id = 1;</text><polygon points="579.17,95.563,569.17,99.563,579.17,103.563,575.17,99.563" fill="#181818" style="stroke:#181818;stroke-width:1;stroke-linejoin:miter;stroke-miterlimit:10;"/><line x1="573.17" y1="99.563" x2="1019.364" y2="99.563" style="stroke:#181818;stroke-width:1;"/><text x="585.17" y="94.497" fill="#000" font-size="13" textLength="214.583">select * from entry where id = 1;</text><path d="M926.799,112.563 L926.799,171.563 L1113.799,171.563 L1113.799,122.563 L1103.799,112.563 L926.799,112.563" style="stroke:#181818;stroke-width:0.5;" fill="#FEFFDD"/><path d="M1103.799,112.563 L1103.799,122.563 L1113.799,122.563 L1103.799,112.563" style="stroke:#181818;stroke-width:0.5;" fill="#FEFFDD"/><text x="932.799" y="129.629" fill="#000" font-size="13" textLength="166.131">Both see the same value:</text><text x="936.931" y="146.762" fill="#000" font-size="13" textLength="11.864">id</text><text x="957.599" y="146.762" fill="#000" font-size="13" textLength="35.509">value</text><text x="941.063" y="161.895" fill="#000" font-size="13">1</text><text x="957.599" y="161.895" fill="#000" font-size="13" textLength="16.542">10</text><line x1="932.799" y1="134.695" x2="997.24" y2="134.695" style="stroke:#000;stroke-width:0.5;"/><line x1="932.799" y1="149.828" x2="997.24" y2="149.828" style="stroke:#000;stroke-width:0.5;"/><line x1="932.799" y1="164.961" x2="997.24" y2="164.961" style="stroke:#000;stroke-width:0.5;"/><line x1="932.799" y1="134.695" x2="932.799" y2="164.961" style="stroke:#000;stroke-width:0.5;"/><line x1="953.467" y1="134.695" x2="953.467" y2="164.961" style="stroke:#000;stroke-width:0.5;"/><line x1="997.24" y1="134.695" x2="997.24" y2="164.961" style="stroke:#000;stroke-width:0.5;"/><polygon points="556.17,209.227,566.17,213.227,556.17,217.227,560.17,213.227" fill="#181818" style="stroke:#181818;stroke-width:1;stroke-linejoin:miter;stroke-miterlimit:10;"/><line x1="124.247" y1="213.227" x2="562.17" y2="213.227" style="stroke:#181818;stroke-width:1;"/><text x="131.247" y="193.028" fill="#000" font-size="13" textLength="419.923">update entry set value = value - 5 where id = 1 and value = 10;</text><text x="131.247" y="208.161" fill="#000" font-size="13"> </text><path d="M15,226.227 L15,285.227 L233,285.227 L233,236.227 L223,226.227 L15,226.227" style="stroke:#181818;stroke-width:0.5;" fill="#FEFFDD"/><path d="M223,226.227 L223,236.227 L233,236.227 L223,226.227" style="stroke:#181818;stroke-width:0.5;" fill="#FEFFDD"/><text x="21" y="243.293" fill="#000" font-size="13" textLength="197.495">Alice's transaction succeeded:</text><text x="25.132" y="260.426" fill="#000" font-size="13" textLength="11.864">id</text><text x="45.8" y="260.426" fill="#000" font-size="13" textLength="35.509">value</text><text x="29.265" y="275.559" fill="#000" font-size="13">1</text><text x="45.8" y="275.559" fill="#000" font-size="13">5</text><line x1="21" y1="248.359" x2="85.441" y2="248.359" style="stroke:#000;stroke-width:0.5;"/><line x1="21" y1="263.492" x2="85.441" y2="263.492" style="stroke:#000;stroke-width:0.5;"/><line x1="21" y1="278.625" x2="85.441" y2="278.625" style="stroke:#000;stroke-width:0.5;"/><line x1="21" y1="248.359" x2="21" y2="278.625" style="stroke:#000;stroke-width:0.5;"/><line x1="41.668" y1="248.359" x2="41.668" y2="278.625" style="stroke:#000;stroke-width:0.5;"/><line x1="85.441" y1="248.359" x2="85.441" y2="278.625" style="stroke:#000;stroke-width:0.5;"/><polygon points="579.17,322.891,569.17,326.891,579.17,330.891,575.17,326.891" fill="#181818" style="stroke:#181818;stroke-width:1;stroke-linejoin:miter;stroke-miterlimit:10;"/><line x1="573.17" y1="326.891" x2="1019.364" y2="326.891" style="stroke:#181818;stroke-width:1;"/><text x="585.17" y="306.692" fill="#000" font-size="13" textLength="428.194">update entry set value = value - 10 where id = 1 and value = 10;</text><text x="585.17" y="321.825" fill="#000" font-size="13"> </text><path d="M776.899,339.891 L776.899,398.891 L1262.899,398.891 L1262.899,349.891 L1252.899,339.891 L776.899,339.891" style="stroke:#181818;stroke-width:0.5;" fill="#FEFFDD"/><path d="M1252.899,339.891 L1252.899,349.891 L1262.899,349.891 L1252.899,339.891" style="stroke:#181818;stroke-width:0.5;" fill="#FEFFDD"/><text x="782.899" y="356.958" fill="#000" font-size="13" textLength="465.931">Bob's transaction did not affect any rows, since the value has changed:</text><text x="787.031" y="374.09" fill="#000" font-size="13" textLength="11.864">id</text><text x="807.699" y="374.09" fill="#000" font-size="13" textLength="35.509">value</text><text x="791.163" y="389.223" fill="#000" font-size="13">1</text><text x="807.699" y="389.223" fill="#000" font-size="13">5</text><line x1="782.899" y1="362.023" x2="847.34" y2="362.023" style="stroke:#000;stroke-width:0.5;"/><line x1="782.899" y1="377.156" x2="847.34" y2="377.156" style="stroke:#000;stroke-width:0.5;"/><line x1="782.899" y1="392.289" x2="847.34" y2="392.289" style="stroke:#000;stroke-width:0.5;"/><line x1="782.899" y1="362.023" x2="782.899" y2="392.289" style="stroke:#000;stroke-width:0.5;"/><line x1="803.567" y1="362.023" x2="803.567" y2="392.289" style="stroke:#000;stroke-width:0.5;"/><line x1="847.34" y1="362.023" x2="847.34" y2="392.289" style="stroke:#000;stroke-width:0.5;"/><polygon points="579.17,421.422,569.17,425.422,579.17,429.422,575.17,425.422" fill="#181818" style="stroke:#181818;stroke-width:1;stroke-linejoin:miter;stroke-miterlimit:10;"/><line x1="573.17" y1="425.422" x2="1019.364" y2="425.422" style="stroke:#181818;stroke-width:1;"/><text x="585.17" y="420.356" fill="#000" font-size="13" textLength="142.391">select ROW_COUNT();</text><path d="M792.65,438.422 L792.65,463.422 L1247.65,463.422 L1247.65,448.422 L1237.65,438.422 L792.65,438.422" style="stroke:#181818;stroke-width:0.5;" fill="#FEFFDD"/><path d="M1237.65,438.422 L1237.65,448.422 L1247.65,448.422 L1237.65,438.422" style="stroke:#181818;stroke-width:0.5;" fill="#FEFFDD"/><text x="798.65" y="455.489" fill="#000" font-size="13" textLength="434.427">ROW_COUNT() returns 0, since the update did not affect any rows.</text><?plantuml-src dP9DImCn48Rl-HNlpIgsx1vwQQdGrRC5KRm8aYQp9h1D9Ccs5FR7cyskkYsLgZdaS-QTPsQohBGWZ6zmLs06JnM9W2kKpcv09hWzTeeSGKiiaCzPOTT_i6R61eBTaaDqP8YZi455Jq9G1CytX2slQfgbnwRrRBeRDFqLyZZbMJemCXAjA6FB0_BwNV8OgeFm57gDHR-ECJr00uywdoPvDdynGzOadQAdtOL7SDnuBeAs1huMWaYIFCSynJ7pi7fdYMFAlqV-Bk_w25Vg51syBDjkSRE7ipj_3Q-DwDhGgIhk8HGtR__83AS-niFg-VLszNJ_EBeyyHK6ht0KQcSyiY5LNw0V-2TVmJy0?></g></svg>'>
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<h2 id="Roll-your-own-locking"><a href="#Roll-your-own-locking" class="headerlink" title="Roll your own locking"></a>Roll your own locking</h2><p>If locking via the database is not enough for your use case, you can implement your own locking mechanism, e.g. with Redis or Memcached. </p>
|
||
<h2 id="References"><a href="#References" class="headerlink" title="References"></a>References</h2><ul>
|
||
<li><a href="https://vladmihalcea.com/a-beginners-guide-to-database-locking-and-the-lost-update-phenomena/">A beginner’s guide to database locking and the lost update phenomena</a></li>
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