结果集不稳定 | TiDB 文档中心

link管理

链接快照平台

输入网页链接，自动生成快照
标签化管理网页链接

相关文章推荐

欢快的咖啡 · sqlite ...· 11 月前 ·

宽容的领带 · Ubuntu18.04 ...· 1 年前 ·

坚韧的充值卡 · 趣书网app下载手机版-趣书网手机TXT下载 ...· 1 年前 ·

坚强的脸盆 · Developer Community· 1 年前 ·

气宇轩昂的蜡烛 · 锂电池级PVDF |聚偏二氟乙烯 | 孚诺林· 1 年前 ·

</noscript><noscript><iframe src="https://www.googletagmanager.com/ns.html?id=GTM-TPX49SBK" height="0" width="0" style="display: none; visibility: hidden" aria-hidden="true"/></noscript><div id="___gatsby"><div style="outline:none" tabindex="-1" id="gatsby-focus-wrapper"><header class="MuiPaper-root MuiPaper-elevation MuiPaper-elevation4 MuiAppBar-root MuiAppBar-colorPrimary MuiAppBar-positionFixed doc-site-header mui-fixed css-r4hqpc"><div class="MuiToolbar-root MuiToolbar-gutters MuiToolbar-regular css-11fgfqk"><button class="MuiButtonBase-root MuiIconButton-root MuiIconButton-sizeMedium css-iuftj9" tabindex="0" type="button" aria-label="menu"><svg class="MuiSvgIcon-root MuiSvgIcon-fontSizeMedium css-vubbuv" focusable="false" aria-hidden="true" viewbox="0 0 24 24" data-testid="MenuIcon"><path d="M3 18h18v-2H3v2zm0-5h18v-2H3v2zm0-7v2h18V6H3z"/></svg></button><div class="MuiBox-root css-13tqxrv"><a style="text-decoration:none" href="/zh"><svg width="152" height="36" viewbox="0 0 152 36" fill="none"><g clip-path="url(#clip0_789_1365)"><path d="M0 26.9605V9.04959C0 9.01208 0.0187549 8.98395 0.0468872 8.96519L15.5478 0.00973267C15.5759 -0.00902222 15.6134 -0.00902222 15.6416 0.00973267L31.1425 8.95581C31.1706 8.97457 31.1894 9.0027 31.1894 9.04021V26.9511C31.1894 26.9886 31.1706 27.0168 31.1425 27.0355L15.6416 35.991C15.6134 36.0097 15.5759 36.0097 15.5478 35.991L0.0468872 27.0355C0.0187549 27.0168 0 26.9886 0 26.9605Z" fill="#DC150B"/><path d="M10.3808 15.0336C10.3714 15.0242 10.3527 15.0149 10.3433 15.0242L5.25136 17.9688H5.2326C5.21384 17.9688 5.20447 17.9594 5.20447 17.9406V12.0047C5.20447 11.9953 5.21384 11.986 5.22322 11.9766L5.22322 11.9766L15.5572 6.01253C15.5665 6.00315 15.5759 6.00315 15.5853 6.01253L20.7241 8.9758L20.7335 8.98518C20.7429 8.99455 20.7335 9.01331 20.7241 9.02268L15.5759 11.9953C15.5665 12.0047 15.5572 12.0141 15.5572 12.0235V29.9625V29.9813C15.5478 29.9906 15.529 30 15.5197 29.9906L10.3902 27.0368C10.3902 27.0274 10.3808 27.018 10.3808 27.0086V15.0524V15.0336Z" fill="white"/><path d="M20.7992 26.9992C20.7804 26.9992 20.7616 26.9805 20.7616 26.9617V15.0336C20.7616 15.0149 20.771 15.0055 20.7804 14.9961L25.9286 12.0235L25.9286 12.0235C25.938 12.0141 25.938 12.0141 25.9474 12.0141C25.9661 12.0141 25.9849 12.0328 25.9849 12.0516V23.9797C25.9849 23.9985 25.9755 24.0078 25.9661 24.0172L20.8179 26.9899C20.8085 26.9992 20.8085 26.9992 20.7992 26.9992Z" fill="white"/></g><path d="M37.1894 12.4971H42.0242V26.9998H45.4248V12.4971H50.2596V9.37683H37.1894V12.4971Z" fill="black"/><path d="M53.6372 9C53.1197 9 52.6672 9.18709 52.2887 9.55826C51.9102 9.92943 51.7151 10.3941 51.7151 10.9373C51.7151 11.4503 51.9073 11.8999 52.2858 12.2802C52.6643 12.6574 53.1167 12.8505 53.6342 12.8505C54.1517 12.8505 54.5775 12.6574 54.9501 12.2802C55.3227 11.903 55.509 11.4503 55.509 10.9373C55.509 10.3941 55.3257 9.93245 54.9619 9.56128C54.5982 9.19011 54.1517 9.00302 53.6372 9.00302V9Z" fill="black"/><path d="M55.2895 14.3592H51.9864V27H55.2895V14.3592Z" fill="black"/><path d="M64.3322 9.37683H58.2613V26.9998H64.3322C66.9492 26.9998 69.028 26.2031 70.5124 24.6309C71.9939 23.0587 72.748 20.8921 72.748 18.1883C72.748 15.4845 71.9969 13.2967 70.5124 11.7336C69.028 10.1705 66.9492 9.37683 64.3322 9.37683ZM61.6619 12.4971H64.2109C65.9024 12.4971 67.1798 12.998 68.0137 13.9847C68.8506 14.9775 69.2734 16.3566 69.2734 18.0857C69.2734 19.8148 68.8476 21.2512 68.0108 22.3013C67.1769 23.3454 65.8994 23.8765 64.208 23.8765H61.659V12.494L61.6619 12.4971Z" fill="black"/><path d="M86.5964 19.1388C86.0346 18.4418 85.3663 17.9409 84.6152 17.6512V17.621C86.1883 16.8424 86.9838 15.566 86.9838 13.8278C86.9838 12.479 86.5461 11.3866 85.6856 10.5839C84.8251 9.78421 83.5566 9.37683 81.9154 9.37683H74.7948V26.9998H81.8681C83.6068 26.9998 84.9907 26.5652 85.9784 25.7082C86.972 24.8482 87.4747 23.6261 87.4747 22.075C87.4747 20.8468 87.179 19.8601 86.5994 19.1388H86.5964ZM78.1185 16.5256V12.1953H81.4718C82.1105 12.1953 82.628 12.3884 83.0095 12.7686C83.388 13.1489 83.5802 13.68 83.5802 14.3499C83.5802 15.0198 83.3909 15.5569 83.0184 15.9432C82.6458 16.3294 82.1105 16.5256 81.4216 16.5256H78.1156H78.1185ZM83.9972 21.8245C83.9972 22.5276 83.7872 23.101 83.3762 23.5295C82.9651 23.958 82.356 24.1753 81.5724 24.1753H78.1215V19.3471H81.5724C82.3235 19.3471 82.9237 19.5794 83.3525 20.0411C83.7813 20.5028 84.0001 21.1033 84.0001 21.8215L83.9972 21.8245Z" fill="black"/><path d="M97.3306 26.5V9.7H102.299C107.771 9.7 111.083 12.868 111.083 18.1C111.083 23.332 107.771 26.5 102.299 26.5H97.3306ZM102.299 24.364C106.331 24.364 108.659 22.06 108.659 18.1C108.659 14.14 106.331 11.836 102.299 11.836H99.7066V24.364H102.299ZM118.968 26.764C115.464 26.764 112.824 24.052 112.824 20.5C112.824 16.948 115.464 14.236 118.968 14.236C122.472 14.236 125.112 16.948 125.112 20.5C125.112 24.052 122.472 26.764 118.968 26.764ZM118.968 24.628C121.152 24.628 122.736 22.876 122.736 20.5C122.736 18.124 121.152 16.372 118.968 16.372C116.784 16.372 115.2 18.124 115.2 20.5C115.2 22.876 116.784 24.628 118.968 24.628ZM132.772 26.764C129.22 26.764 126.7 24.124 126.7 20.5C126.7 16.876 129.22 14.236 132.772 14.236C135.652 14.236 137.884 15.964 138.244 18.532H135.844C135.532 17.236 134.332 16.372 132.772 16.372C130.588 16.372 129.076 18.076 129.076 20.5C129.076 22.9 130.588 24.628 132.772 24.628C134.332 24.628 135.532 23.764 135.844 22.468H138.244C137.884 25.036 135.652 26.764 132.772 26.764ZM144.557 26.764C141.677 26.764 139.781 25.108 139.709 22.732H142.085C142.229 23.956 142.973 24.724 144.581 24.724C145.733 24.724 146.765 24.34 146.765 23.332C146.765 22.588 146.333 22.06 145.157 21.7L143.333 21.172C141.173 20.548 140.093 19.3 140.093 17.716C140.093 15.604 141.965 14.236 144.413 14.236C146.885 14.236 148.685 15.7 148.829 17.74H146.453C146.285 16.828 145.445 16.204 144.341 16.204C143.261 16.204 142.469 16.804 142.469 17.716C142.469 18.412 142.925 18.868 144.245 19.228L146.069 19.732C148.109 20.308 149.141 21.556 149.141 23.188C149.141 25.396 147.197 26.764 144.557 26.764Z" fill="black"/><defs><clippath id="clip0_789_1365"><rect width="31.1894" height="36" fill="white"/></clippath></defs></svg></a></div><div class="css-2iqpys"><div class="MuiBox-root css-irbys9"><a style="text-decoration:none" hreflang="zh" href="/zh/tidb/stable"><div class="MuiTypography-root MuiTypography-body1 css-jhf72c">TiDB</div></a></div><div class="MuiBox-root css-kiou0g"><a class="MuiTypography-root MuiTypography-body1 css-z7v9yr" target="_blank" href="https://asktug.com/" style="text-decoration:none"><div class="MuiTypography-root MuiTypography-body1 css-jhf72c">社区</div></a></div><div class="MuiBox-root css-kiou0g"><a class="MuiTypography-root MuiTypography-body1 css-z7v9yr" target="_blank" href="https://cn.pingcap.com/contact/" style="text-decoration:none"><div class="MuiTypography-root MuiTypography-body1 css-jhf72c">联系我们</div></a></div><div class="MuiBox-root css-kiou0g"><a class="MuiTypography-root MuiTypography-body1 css-z7v9yr" target="_blank" href="https://cn.pingcap.com/product/#SelectProduct" style="text-decoration:none"><div class="MuiTypography-root MuiTypography-body1 css-jhf72c"><svg class="MuiSvgIcon-root MuiSvgIcon-fontSizeInherit css-1cw4hi4" focusable="false" aria-hidden="true" viewbox="0 0 24 24" data-testid="DownloadIcon"><path d="M5 20h14v-2H5v2zM19 9h-4V3H9v6H5l7 7 7-7z"/></svg></div></a></div></div><div class="MuiBox-root css-1vn3uc0"><button class="MuiButtonBase-root MuiButton-root MuiButton-text MuiButton-textInherit MuiButton-sizeMedium MuiButton-textSizeMedium MuiButton-colorInherit MuiButton-disableElevation css-tjg32r" tabindex="0" type="button" id="header-nav-items" aria-haspopup="true"><span class="MuiButton-startIcon MuiButton-iconSizeMedium css-1l6c7y9"><svg width="152" height="36" viewbox="0 0 152 36" fill="none"><g clip-path="url(#clip0_789_1365)"><path d="M0 26.9605V9.04959C0 9.01208 0.0187549 8.98395 0.0468872 8.96519L15.5478 0.00973267C15.5759 -0.00902222 15.6134 -0.00902222 15.6416 0.00973267L31.1425 8.95581C31.1706 8.97457 31.1894 9.0027 31.1894 9.04021V26.9511C31.1894 26.9886 31.1706 27.0168 31.1425 27.0355L15.6416 35.991C15.6134 36.0097 15.5759 36.0097 15.5478 35.991L0.0468872 27.0355C0.0187549 27.0168 0 26.9886 0 26.9605Z" fill="#DC150B"/><path d="M10.3808 15.0336C10.3714 15.0242 10.3527 15.0149 10.3433 15.0242L5.25136 17.9688H5.2326C5.21384 17.9688 5.20447 17.9594 5.20447 17.9406V12.0047C5.20447 11.9953 5.21384 11.986 5.22322 11.9766L5.22322 11.9766L15.5572 6.01253C15.5665 6.00315 15.5759 6.00315 15.5853 6.01253L20.7241 8.9758L20.7335 8.98518C20.7429 8.99455 20.7335 9.01331 20.7241 9.02268L15.5759 11.9953C15.5665 12.0047 15.5572 12.0141 15.5572 12.0235V29.9625V29.9813C15.5478 29.9906 15.529 30 15.5197 29.9906L10.3902 27.0368C10.3902 27.0274 10.3808 27.018 10.3808 27.0086V15.0524V15.0336Z" fill="white"/><path d="M20.7992 26.9992C20.7804 26.9992 20.7616 26.9805 20.7616 26.9617V15.0336C20.7616 15.0149 20.771 15.0055 20.7804 14.9961L25.9286 12.0235L25.9286 12.0235C25.938 12.0141 25.938 12.0141 25.9474 12.0141C25.9661 12.0141 25.9849 12.0328 25.9849 12.0516V23.9797C25.9849 23.9985 25.9755 24.0078 25.9661 24.0172L20.8179 26.9899C20.8085 26.9992 20.8085 26.9992 20.7992 26.9992Z" fill="white"/></g><path d="M37.1894 12.4971H42.0242V26.9998H45.4248V12.4971H50.2596V9.37683H37.1894V12.4971Z" fill="black"/><path d="M53.6372 9C53.1197 9 52.6672 9.18709 52.2887 9.55826C51.9102 9.92943 51.7151 10.3941 51.7151 10.9373C51.7151 11.4503 51.9073 11.8999 52.2858 12.2802C52.6643 12.6574 53.1167 12.8505 53.6342 12.8505C54.1517 12.8505 54.5775 12.6574 54.9501 12.2802C55.3227 11.903 55.509 11.4503 55.509 10.9373C55.509 10.3941 55.3257 9.93245 54.9619 9.56128C54.5982 9.19011 54.1517 9.00302 53.6372 9.00302V9Z" fill="black"/><path d="M55.2895 14.3592H51.9864V27H55.2895V14.3592Z" fill="black"/><path d="M64.3322 9.37683H58.2613V26.9998H64.3322C66.9492 26.9998 69.028 26.2031 70.5124 24.6309C71.9939 23.0587 72.748 20.8921 72.748 18.1883C72.748 15.4845 71.9969 13.2967 70.5124 11.7336C69.028 10.1705 66.9492 9.37683 64.3322 9.37683ZM61.6619 12.4971H64.2109C65.9024 12.4971 67.1798 12.998 68.0137 13.9847C68.8506 14.9775 69.2734 16.3566 69.2734 18.0857C69.2734 19.8148 68.8476 21.2512 68.0108 22.3013C67.1769 23.3454 65.8994 23.8765 64.208 23.8765H61.659V12.494L61.6619 12.4971Z" fill="black"/><path d="M86.5964 19.1388C86.0346 18.4418 85.3663 17.9409 84.6152 17.6512V17.621C86.1883 16.8424 86.9838 15.566 86.9838 13.8278C86.9838 12.479 86.5461 11.3866 85.6856 10.5839C84.8251 9.78421 83.5566 9.37683 81.9154 9.37683H74.7948V26.9998H81.8681C83.6068 26.9998 84.9907 26.5652 85.9784 25.7082C86.972 24.8482 87.4747 23.6261 87.4747 22.075C87.4747 20.8468 87.179 19.8601 86.5994 19.1388H86.5964ZM78.1185 16.5256V12.1953H81.4718C82.1105 12.1953 82.628 12.3884 83.0095 12.7686C83.388 13.1489 83.5802 13.68 83.5802 14.3499C83.5802 15.0198 83.3909 15.5569 83.0184 15.9432C82.6458 16.3294 82.1105 16.5256 81.4216 16.5256H78.1156H78.1185ZM83.9972 21.8245C83.9972 22.5276 83.7872 23.101 83.3762 23.5295C82.9651 23.958 82.356 24.1753 81.5724 24.1753H78.1215V19.3471H81.5724C82.3235 19.3471 82.9237 19.5794 83.3525 20.0411C83.7813 20.5028 84.0001 21.1033 84.0001 21.8215L83.9972 21.8245Z" fill="black"/><path d="M97.3306 26.5V9.7H102.299C107.771 9.7 111.083 12.868 111.083 18.1C111.083 23.332 107.771 26.5 102.299 26.5H97.3306ZM102.299 24.364C106.331 24.364 108.659 22.06 108.659 18.1C108.659 14.14 106.331 11.836 102.299 11.836H99.7066V24.364H102.299ZM118.968 26.764C115.464 26.764 112.824 24.052 112.824 20.5C112.824 16.948 115.464 14.236 118.968 14.236C122.472 14.236 125.112 16.948 125.112 20.5C125.112 24.052 122.472 26.764 118.968 26.764ZM118.968 24.628C121.152 24.628 122.736 22.876 122.736 20.5C122.736 18.124 121.152 16.372 118.968 16.372C116.784 16.372 115.2 18.124 115.2 20.5C115.2 22.876 116.784 24.628 118.968 24.628ZM132.772 26.764C129.22 26.764 126.7 24.124 126.7 20.5C126.7 16.876 129.22 14.236 132.772 14.236C135.652 14.236 137.884 15.964 138.244 18.532H135.844C135.532 17.236 134.332 16.372 132.772 16.372C130.588 16.372 129.076 18.076 129.076 20.5C129.076 22.9 130.588 24.628 132.772 24.628C134.332 24.628 135.532 23.764 135.844 22.468H138.244C137.884 25.036 135.652 26.764 132.772 26.764ZM144.557 26.764C141.677 26.764 139.781 25.108 139.709 22.732H142.085C142.229 23.956 142.973 24.724 144.581 24.724C145.733 24.724 146.765 24.34 146.765 23.332C146.765 22.588 146.333 22.06 145.157 21.7L143.333 21.172C141.173 20.548 140.093 19.3 140.093 17.716C140.093 15.604 141.965 14.236 144.413 14.236C146.885 14.236 148.685 15.7 148.829 17.74H146.453C146.285 16.828 145.445 16.204 144.341 16.204C143.261 16.204 142.469 16.804 142.469 17.716C142.469 18.412 142.925 18.868 144.245 19.228L146.069 19.732C148.109 20.308 149.141 21.556 149.141 23.188C149.141 25.396 147.197 26.764 144.557 26.764Z" fill="black"/><defs><clippath id="clip0_789_1365"><rect width="31.1894" height="36" fill="white"/></clippath></defs></svg></span><span class="MuiButton-endIcon MuiButton-iconSizeMedium css-pt151d"><svg class="MuiSvgIcon-root MuiSvgIcon-fontSizeMedium css-vubbuv" focusable="false" aria-hidden="true" viewbox="0 0 24 24" data-testid="KeyboardArrowDownIcon"><path d="M7.41 8.59 12 13.17l4.59-4.58L18 10l-6 6-6-6 1.41-1.41z"/></svg></span></button></div><div class="css-1w2hxsf"><div class="MuiBox-root css-19itmc6"><button class="MuiButtonBase-root MuiIconButton-root MuiIconButton-sizeMedium css-jwr93t" tabindex="0" type="button"><svg class="MuiSvgIcon-root MuiSvgIcon-fontSizeMedium css-vubbuv" focusable="false" aria-hidden="true" viewbox="0 0 24 24" data-testid="TranslateIcon"><path d="m12.87 15.07-2.54-2.51.03-.03c1.74-1.94 2.98-4.17 3.71-6.53H17V4h-7V2H8v2H1v1.99h11.17C11.5 7.92 10.44 9.75 9 11.35 8.07 10.32 7.3 9.19 6.69 8h-2c.73 1.63 1.73 3.17 2.98 4.56l-5.09 5.02L4 19l5-5 3.11 3.11.76-2.04zM18.5 10h-2L12 22h2l1.12-3h4.75L21 22h2l-4.5-12zm-2.62 7 1.62-4.33L19.12 17h-3.24z"/></svg></button><button class="MuiButtonBase-root MuiButton-root MuiButton-text MuiButton-textInherit MuiButton-sizeMedium MuiButton-textSizeMedium MuiButton-colorInherit MuiButton-disableElevation css-1r5wmim" tabindex="0" type="button" id="header-lang-switch" aria-haspopup="true"><span class="MuiButton-startIcon MuiButton-iconSizeMedium css-1l6c7y9"><svg class="MuiSvgIcon-root MuiSvgIcon-fontSizeMedium css-1msahp5" focusable="false" aria-hidden="true" viewbox="0 0 24 24" data-testid="TranslateIcon"><path d="m12.87 15.07-2.54-2.51.03-.03c1.74-1.94 2.98-4.17 3.71-6.53H17V4h-7V2H8v2H1v1.99h11.17C11.5 7.92 10.44 9.75 9 11.35 8.07 10.32 7.3 9.19 6.69 8h-2c.73 1.63 1.73 3.17 2.98 4.56l-5.09 5.02L4 19l5-5 3.11 3.11.76-2.04zM18.5 10h-2L12 22h2l1.12-3h4.75L21 22h2l-4.5-12zm-2.62 7 1.62-4.33L19.12 17h-3.24z"/></svg></span><span class="MuiButton-endIcon MuiButton-iconSizeMedium css-pt151d"><svg class="MuiSvgIcon-root MuiSvgIcon-fontSizeMedium css-1msahp5" focusable="false" aria-hidden="true" viewbox="0 0 24 24" data-testid="KeyboardArrowDownIcon"><path d="M7.41 8.59 12 13.17l4.59-4.58L18 10l-6 6-6-6 1.41-1.41z"/></svg></span></button></div><div class="css-1iegyem"><div class="MuiBox-root css-0"><button class="MuiButtonBase-root MuiIconButton-root MuiIconButton-sizeMedium css-iuftj9" tabindex="0" type="button"><svg class="MuiSvgIcon-root MuiSvgIcon-fontSizeMedium css-vubbuv" focusable="false" aria-hidden="true" viewbox="0 0 24 24" data-testid="SearchIcon"><path d="M15.5 14h-.79l-.28-.27C15.41 12.59 16 11.11 16 9.5 16 5.91 13.09 3 9.5 3S3 5.91 3 9.5 5.91 16 9.5 16c1.61 0 3.09-.59 4.23-1.57l.27.28v.79l5 4.99L20.49 19l-4.99-5zm-6 0C7.01 14 5 11.99 5 9.5S7.01 5 9.5 5 14 7.01 14 9.5 11.99 14 9.5 14z"/></svg></button><form class="MuiBox-root css-1dl8tgy" novalidate="" autocomplete="off"><div class="MuiFormControl-root MuiFormControl-fullWidth MuiTextField-root css-7omol5"><div class="MuiInputBase-root MuiOutlinedInput-root MuiInputBase-colorPrimary MuiInputBase-fullWidth MuiInputBase-formControl MuiInputBase-sizeSmall MuiInputBase-adornedStart css-10r6rap"><div class="MuiInputAdornment-root MuiInputAdornment-positionStart MuiInputAdornment-outlined MuiInputAdornment-sizeSmall css-1a6giau"><span class="notranslate"></span><svg class="MuiSvgIcon-root MuiSvgIcon-fontSizeSmall css-1k33q06" focusable="false" aria-hidden="true" viewbox="0 0 24 24" data-testid="SearchIcon"><path d="M15.5 14h-.79l-.28-.27C15.41 12.59 16 11.11 16 9.5 16 5.91 13.09 3 9.5 3S3 5.91 3 9.5 5.91 16 9.5 16c1.61 0 3.09-.59 4.23-1.57l.27.28v.79l5 4.99L20.49 19l-4.99-5zm-6 0C7.01 14 5 11.99 5 9.5S7.01 5 9.5 5 14 7.01 14 9.5 11.99 14 9.5 14z"/></svg></div><input type="search" aria-invalid="false" id="doc-search" placeholder="搜索文档" value="" class="MuiInputBase-input MuiOutlinedInput-input MuiInputBase-inputTypeSearch MuiInputBase-inputSizeSmall MuiInputBase-inputAdornedStart css-1a7iucg"/><fieldset aria-hidden="true" class="MuiOutlinedInput-notchedOutline css-igs3ac"><legend class="css-hdw1oc"><span class="notranslate"></span></legend></fieldset></div></div></form></div></div></div></div></header><div class="PingCAP-Doc MuiBox-root css-s1brf2"><div class="MuiBox-root css-hboir5"><aside class="MuiBox-root css-2tzg8"><div class="MuiBox-root css-ysaqso"><button class="MuiButtonBase-root MuiButton-root MuiButton-text MuiButton-textPrimary MuiButton-sizeMedium MuiButton-textSizeMedium MuiButton-disableElevation css-1q0sqyi" tabindex="0" type="button" id="version-select-button" aria-haspopup="true"><div class="MuiTypography-root MuiTypography-body1 css-hg1lfe">dev</div><span class="MuiButton-endIcon MuiButton-iconSizeMedium css-pt151d"><svg class="MuiSvgIcon-root MuiSvgIcon-fontSizeMedium css-1rrdqpg" focusable="false" aria-hidden="true" viewbox="0 0 24 24" data-testid="ChevronRightIcon"><path d="M10 6 8.59 7.41 13.17 12l-4.58 4.59L10 18l6-6z"/></svg></span></button><ul role="tree" id="left-nav-treeview" aria-multiselectable="false" class="MuiTreeView-root css-12mehxg" tabindex="0" aria-label="left navigation"><a class="MuiTypography-root MuiTypography-body1 css-z7v9yr" target="_blank" href="https://docs.pingcap.com/zh" style="text-decoration:none;width:100%;color:inherit"><li class="MuiTreeItem-root css-14t19hb" role="treeitem" id="left-nav-treeview-0-0" tabindex="-1" style="margin-top:0.1875rem;margin-bottom:0.1875rem"><div class="css-zfdk9c MuiTreeItem-content" style="width:inherit"><div class="MuiTreeItem-iconContainer"/><div class="MuiTreeItem-label"><div class="css-w8t2sr"><div class="MuiBox-root css-3o0h5k"/><div class="MuiBox-root css-8atqhb"><div class="MuiTypography-root MuiTypography-body1 css-1rc6ywa">文档中心</div></div></div></div></div></li></a><li class="MuiTreeItem-root css-14t19hb" role="treeitem" aria-expanded="false" id="left-nav-treeview-0-1" tabindex="-1" style="margin-top:0.1875rem;margin-bottom:0.1875rem"><div class="css-zfdk9c MuiTreeItem-content" style="width:inherit"><div class="MuiTreeItem-iconContainer"/><div class="MuiTreeItem-label"><div class="css-w8t2sr"><svg class="MuiSvgIcon-root MuiSvgIcon-fontSizeMedium MuiTreeItem-ChevronRightIcon css-hkir54" focusable="false" aria-hidden="true" viewbox="0 0 24 24" data-testid="ChevronRightIcon"><path d="M10 6 8.59 7.41 13.17 12l-4.58 4.59L10 18l6-6z"/></svg><div class="MuiBox-root css-8atqhb"><div class="MuiTypography-root MuiTypography-body1 css-1rc6ywa">关于 TiDB</div></div></div></div></div></li><li class="MuiTreeItem-root css-14t19hb" role="treeitem" aria-expanded="false" id="left-nav-treeview-0-2" tabindex="-1" style="margin-top:0.1875rem;margin-bottom:0.1875rem"><div class="css-zfdk9c MuiTreeItem-content" style="width:inherit"><div class="MuiTreeItem-iconContainer"/><div class="MuiTreeItem-label"><div class="css-w8t2sr"><svg class="MuiSvgIcon-root MuiSvgIcon-fontSizeMedium MuiTreeItem-ChevronRightIcon css-hkir54" focusable="false" aria-hidden="true" viewbox="0 0 24 24" data-testid="ChevronRightIcon"><path d="M10 6 8.59 7.41 13.17 12l-4.58 4.59L10 18l6-6z"/></svg><div class="MuiBox-root css-8atqhb"><div class="MuiTypography-root MuiTypography-body1 css-1rc6ywa">快速上手</div></div></div></div></div></li><li class="MuiTreeItem-root css-14t19hb" role="treeitem" aria-expanded="true" id="left-nav-treeview-0-3" tabindex="-1" style="margin-top:0.1875rem;margin-bottom:0.1875rem"><div class="css-zfdk9c MuiTreeItem-content Mui-expanded" style="width:inherit"><div class="MuiTreeItem-iconContainer"/><div class="MuiTreeItem-label"><div class="css-w8t2sr"><svg class="MuiSvgIcon-root MuiSvgIcon-fontSizeMedium MuiTreeItem-ChevronRightIcon css-13dmm4z" focusable="false" aria-hidden="true" viewbox="0 0 24 24" data-testid="ChevronRightIcon"><path d="M10 6 8.59 7.41 13.17 12l-4.58 4.59L10 18l6-6z"/></svg><div class="MuiBox-root css-8atqhb"><div class="MuiTypography-root MuiTypography-body1 css-1rc6ywa">应用开发</div></div></div></div></div><ul class="MuiCollapse-root MuiCollapse-vertical MuiTreeItem-group MuiCollapse-entered css-1xxsnna" style="min-height:0px" role="group"><div class="MuiCollapse-wrapper MuiCollapse-vertical css-hboir5"><div class="MuiCollapse-wrapperInner MuiCollapse-vertical css-8atqhb"><a style="text-decoration:none;width:100%;color:inherit" href="/zh/tidb/dev/dev-guide-overview"><li class="MuiTreeItem-root css-14t19hb" role="treeitem" id="left-nav-treeview-0-3-0" tabindex="-1" style="margin-top:0.1875rem;margin-bottom:0.1875rem"><div class="css-zfdk9c MuiTreeItem-content" style="width:inherit"><div class="MuiTreeItem-iconContainer"/><div class="MuiTreeItem-label"><div class="css-2jyri7"><div class="MuiBox-root css-3o0h5k"/><div class="MuiBox-root css-8atqhb"><div class="MuiTypography-root MuiTypography-body1 css-1rc6ywa">概览</div></div></div></div></div></li></a><li class="MuiTreeItem-root css-14t19hb" role="treeitem" aria-expanded="false" id="left-nav-treeview-0-3-1" tabindex="-1" style="margin-top:0.1875rem;margin-bottom:0.1875rem"><div class="css-zfdk9c MuiTreeItem-content" style="width:inherit"><div class="MuiTreeItem-iconContainer"/><div class="MuiTreeItem-label"><div class="css-2jyri7"><svg class="MuiSvgIcon-root MuiSvgIcon-fontSizeMedium MuiTreeItem-ChevronRightIcon css-hkir54" focusable="false" aria-hidden="true" viewbox="0 0 24 24" data-testid="ChevronRightIcon"><path d="M10 6 8.59 7.41 13.17 12l-4.58 4.59L10 18l6-6z"/></svg><div class="MuiBox-root css-8atqhb"><div class="MuiTypography-root MuiTypography-body1 css-1rc6ywa">快速开始</div></div></div></div></div></li><li class="MuiTreeItem-root css-14t19hb" role="treeitem" aria-expanded="false" id="left-nav-treeview-0-3-2" tabindex="-1" style="margin-top:0.1875rem;margin-bottom:0.1875rem"><div class="css-zfdk9c MuiTreeItem-content" style="width:inherit"><div class="MuiTreeItem-iconContainer"/><div class="MuiTreeItem-label"><div class="css-2jyri7"><svg class="MuiSvgIcon-root MuiSvgIcon-fontSizeMedium MuiTreeItem-ChevronRightIcon css-hkir54" focusable="false" aria-hidden="true" viewbox="0 0 24 24" data-testid="ChevronRightIcon"><path d="M10 6 8.59 7.41 13.17 12l-4.58 4.59L10 18l6-6z"/></svg><div class="MuiBox-root css-8atqhb"><div class="MuiTypography-root MuiTypography-body1 css-1rc6ywa">示例程序</div></div></div></div></div></li><li class="MuiTreeItem-root css-14t19hb" role="treeitem" aria-expanded="false" id="left-nav-treeview-0-3-3" tabindex="-1" style="margin-top:0.1875rem;margin-bottom:0.1875rem"><div class="css-zfdk9c MuiTreeItem-content" style="width:inherit"><div class="MuiTreeItem-iconContainer"/><div class="MuiTreeItem-label"><div class="css-2jyri7"><svg class="MuiSvgIcon-root MuiSvgIcon-fontSizeMedium MuiTreeItem-ChevronRightIcon css-hkir54" focusable="false" aria-hidden="true" viewbox="0 0 24 24" data-testid="ChevronRightIcon"><path d="M10 6 8.59 7.41 13.17 12l-4.58 4.59L10 18l6-6z"/></svg><div class="MuiBox-root css-8atqhb"><div class="MuiTypography-root MuiTypography-body1 css-1rc6ywa">连接到 TiDB</div></div></div></div></div></li><li class="MuiTreeItem-root css-14t19hb" role="treeitem" aria-expanded="false" id="left-nav-treeview-0-3-4" tabindex="-1" style="margin-top:0.1875rem;margin-bottom:0.1875rem"><div class="css-zfdk9c MuiTreeItem-content" style="width:inherit"><div class="MuiTreeItem-iconContainer"/><div class="MuiTreeItem-label"><div class="css-2jyri7"><svg class="MuiSvgIcon-root MuiSvgIcon-fontSizeMedium MuiTreeItem-ChevronRightIcon css-hkir54" focusable="false" aria-hidden="true" viewbox="0 0 24 24" data-testid="ChevronRightIcon"><path d="M10 6 8.59 7.41 13.17 12l-4.58 4.59L10 18l6-6z"/></svg><div class="MuiBox-root css-8atqhb"><div class="MuiTypography-root MuiTypography-body1 css-1rc6ywa">数据库模式设计</div></div></div></div></div></li><li class="MuiTreeItem-root css-14t19hb" role="treeitem" aria-expanded="false" id="left-nav-treeview-0-3-5" tabindex="-1" style="margin-top:0.1875rem;margin-bottom:0.1875rem"><div class="css-zfdk9c MuiTreeItem-content" style="width:inherit"><div class="MuiTreeItem-iconContainer"/><div class="MuiTreeItem-label"><div class="css-2jyri7"><svg class="MuiSvgIcon-root MuiSvgIcon-fontSizeMedium MuiTreeItem-ChevronRightIcon css-hkir54" focusable="false" aria-hidden="true" viewbox="0 0 24 24" data-testid="ChevronRightIcon"><path d="M10 6 8.59 7.41 13.17 12l-4.58 4.59L10 18l6-6z"/></svg><div class="MuiBox-root css-8atqhb"><div class="MuiTypography-root MuiTypography-body1 css-1rc6ywa">数据写入</div></div></div></div></div></li><li class="MuiTreeItem-root css-14t19hb" role="treeitem" aria-expanded="false" id="left-nav-treeview-0-3-6" tabindex="-1" style="margin-top:0.1875rem;margin-bottom:0.1875rem"><div class="css-zfdk9c MuiTreeItem-content" style="width:inherit"><div class="MuiTreeItem-iconContainer"/><div class="MuiTreeItem-label"><div class="css-2jyri7"><svg class="MuiSvgIcon-root MuiSvgIcon-fontSizeMedium MuiTreeItem-ChevronRightIcon css-hkir54" focusable="false" aria-hidden="true" viewbox="0 0 24 24" data-testid="ChevronRightIcon"><path d="M10 6 8.59 7.41 13.17 12l-4.58 4.59L10 18l6-6z"/></svg><div class="MuiBox-root css-8atqhb"><div class="MuiTypography-root MuiTypography-body1 css-1rc6ywa">数据读取</div></div></div></div></div></li><li class="MuiTreeItem-root css-14t19hb" role="treeitem" aria-expanded="false" id="left-nav-treeview-0-3-7" tabindex="-1" style="margin-top:0.1875rem;margin-bottom:0.1875rem"><div class="css-zfdk9c MuiTreeItem-content" style="width:inherit"><div class="MuiTreeItem-iconContainer"/><div class="MuiTreeItem-label"><div class="css-2jyri7"><svg class="MuiSvgIcon-root MuiSvgIcon-fontSizeMedium MuiTreeItem-ChevronRightIcon css-hkir54" focusable="false" aria-hidden="true" viewbox="0 0 24 24" data-testid="ChevronRightIcon"><path d="M10 6 8.59 7.41 13.17 12l-4.58 4.59L10 18l6-6z"/></svg><div class="MuiBox-root css-8atqhb"><div class="MuiTypography-root MuiTypography-body1 css-1rc6ywa">事务</div></div></div></div></div></li><li class="MuiTreeItem-root css-14t19hb" role="treeitem" aria-expanded="false" id="left-nav-treeview-0-3-8" tabindex="-1" style="margin-top:0.1875rem;margin-bottom:0.1875rem"><div class="css-zfdk9c MuiTreeItem-content" style="width:inherit"><div class="MuiTreeItem-iconContainer"/><div class="MuiTreeItem-label"><div class="css-2jyri7"><svg class="MuiSvgIcon-root MuiSvgIcon-fontSizeMedium MuiTreeItem-ChevronRightIcon css-hkir54" focusable="false" aria-hidden="true" viewbox="0 0 24 24" data-testid="ChevronRightIcon"><path d="M10 6 8.59 7.41 13.17 12l-4.58 4.59L10 18l6-6z"/></svg><div class="MuiBox-root css-8atqhb"><div class="MuiTypography-root MuiTypography-body1 css-1rc6ywa">优化 SQL 性能</div></div></div></div></div></li><li class="MuiTreeItem-root css-14t19hb" role="treeitem" aria-expanded="true" id="left-nav-treeview-0-3-9" tabindex="-1" style="margin-top:0.1875rem;margin-bottom:0.1875rem"><div class="css-zfdk9c MuiTreeItem-content Mui-expanded" style="width:inherit"><div class="MuiTreeItem-iconContainer"/><div class="MuiTreeItem-label"><div class="css-2jyri7"><svg class="MuiSvgIcon-root MuiSvgIcon-fontSizeMedium MuiTreeItem-ChevronRightIcon css-13dmm4z" focusable="false" aria-hidden="true" viewbox="0 0 24 24" data-testid="ChevronRightIcon"><path d="M10 6 8.59 7.41 13.17 12l-4.58 4.59L10 18l6-6z"/></svg><div class="MuiBox-root css-8atqhb"><div class="MuiTypography-root MuiTypography-body1 css-1rc6ywa">故障诊断</div></div></div></div></div><ul class="MuiCollapse-root MuiCollapse-vertical MuiTreeItem-group MuiCollapse-entered css-1xxsnna" style="min-height:0px" role="group"><div class="MuiCollapse-wrapper MuiCollapse-vertical css-hboir5"><div class="MuiCollapse-wrapperInner MuiCollapse-vertical css-8atqhb"><a style="text-decoration:none;width:100%;color:inherit" href="/zh/tidb/dev/dev-guide-troubleshoot-overview"><li class="MuiTreeItem-root css-14t19hb" role="treeitem" id="left-nav-treeview-0-3-9-0" tabindex="-1" style="margin-top:0.1875rem;margin-bottom:0.1875rem"><div class="css-zfdk9c MuiTreeItem-content" style="width:inherit"><div class="MuiTreeItem-iconContainer"/><div class="MuiTreeItem-label"><div class="css-xeut16"><div class="MuiBox-root css-3o0h5k"/><div class="MuiBox-root css-8atqhb"><div class="MuiTypography-root MuiTypography-body1 css-1rc6ywa">SQL 或事务问题</div></div></div></div></div></li></a><a aria-current="page" style="text-decoration:none;width:100%;color:inherit" class="" href="/zh/tidb/dev/dev-guide-unstable-result-set"><li class="MuiTreeItem-root css-14t19hb" role="treeitem" aria-selected="true" id="left-nav-treeview-0-3-9-1" tabindex="-1" style="margin-top:0.1875rem;margin-bottom:0.1875rem"><div class="css-zfdk9c MuiTreeItem-content Mui-expanded Mui-selected" style="width:inherit"><div class="MuiTreeItem-iconContainer"/><div class="MuiTreeItem-label"><div class="css-xeut16"><div class="MuiBox-root css-3o0h5k"/><div class="MuiBox-root css-8atqhb"><div class="MuiTypography-root MuiTypography-body1 css-1rc6ywa">结果集不稳定</div></div></div></div></div></li></a><a style="text-decoration:none;width:100%;color:inherit" href="/zh/tidb/dev/dev-guide-timeouts-in-tidb"><li class="MuiTreeItem-root css-14t19hb" role="treeitem" id="left-nav-treeview-0-3-9-2" tabindex="-1" style="margin-top:0.1875rem;margin-bottom:0.1875rem"><div class="css-zfdk9c MuiTreeItem-content" style="width:inherit"><div class="MuiTreeItem-iconContainer"/><div class="MuiTreeItem-label"><div class="css-xeut16"><div class="MuiBox-root css-3o0h5k"/><div class="MuiBox-root css-8atqhb"><div class="MuiTypography-root MuiTypography-body1 css-1rc6ywa">超时</div></div></div></div></div></li></a></div></div></ul></li><li class="MuiTreeItem-root css-14t19hb" role="treeitem" aria-expanded="false" id="left-nav-treeview-0-3-10" tabindex="-1" style="margin-top:0.1875rem;margin-bottom:0.1875rem"><div class="css-zfdk9c MuiTreeItem-content" style="width:inherit"><div class="MuiTreeItem-iconContainer"/><div class="MuiTreeItem-label"><div class="css-2jyri7"><svg class="MuiSvgIcon-root MuiSvgIcon-fontSizeMedium MuiTreeItem-ChevronRightIcon css-hkir54" focusable="false" aria-hidden="true" viewbox="0 0 24 24" data-testid="ChevronRightIcon"><path d="M10 6 8.59 7.41 13.17 12l-4.58 4.59L10 18l6-6z"/></svg><div class="MuiBox-root css-8atqhb"><div class="MuiTypography-root MuiTypography-body1 css-1rc6ywa">引用文档</div></div></div></div></div></li><li class="MuiTreeItem-root css-14t19hb" role="treeitem" aria-expanded="false" id="left-nav-treeview-0-3-11" tabindex="-1" style="margin-top:0.1875rem;margin-bottom:0.1875rem"><div class="css-zfdk9c MuiTreeItem-content" style="width:inherit"><div class="MuiTreeItem-iconContainer"/><div class="MuiTreeItem-label"><div class="css-2jyri7"><svg class="MuiSvgIcon-root MuiSvgIcon-fontSizeMedium MuiTreeItem-ChevronRightIcon css-hkir54" focusable="false" aria-hidden="true" viewbox="0 0 24 24" data-testid="ChevronRightIcon"><path d="M10 6 8.59 7.41 13.17 12l-4.58 4.59L10 18l6-6z"/></svg><div class="MuiBox-root css-8atqhb"><div class="MuiTypography-root MuiTypography-body1 css-1rc6ywa">云原生开发环境</div></div></div></div></div></li><li class="MuiTreeItem-root css-14t19hb" role="treeitem" aria-expanded="false" id="left-nav-treeview-0-3-12" tabindex="-1" style="margin-top:0.1875rem;margin-bottom:0.1875rem"><div class="css-zfdk9c MuiTreeItem-content" style="width:inherit"><div class="MuiTreeItem-iconContainer"/><div class="MuiTreeItem-label"><div class="css-2jyri7"><svg class="MuiSvgIcon-root MuiSvgIcon-fontSizeMedium MuiTreeItem-ChevronRightIcon css-hkir54" focusable="false" aria-hidden="true" viewbox="0 0 24 24" data-testid="ChevronRightIcon"><path d="M10 6 8.59 7.41 13.17 12l-4.58 4.59L10 18l6-6z"/></svg><div class="MuiBox-root css-8atqhb"><div class="MuiTypography-root MuiTypography-body1 css-1rc6ywa">第三方工具支持</div></div></div></div></div></li></div></div></ul></li><li class="MuiTreeItem-root css-14t19hb" role="treeitem" aria-expanded="false" id="left-nav-treeview-0-4" tabindex="-1" style="margin-top:0.1875rem;margin-bottom:0.1875rem"><div class="css-zfdk9c MuiTreeItem-content" style="width:inherit"><div class="MuiTreeItem-iconContainer"/><div class="MuiTreeItem-label"><div class="css-w8t2sr"><svg class="MuiSvgIcon-root MuiSvgIcon-fontSizeMedium MuiTreeItem-ChevronRightIcon css-hkir54" focusable="false" aria-hidden="true" viewbox="0 0 24 24" data-testid="ChevronRightIcon"><path d="M10 6 8.59 7.41 13.17 12l-4.58 4.59L10 18l6-6z"/></svg><div class="MuiBox-root css-8atqhb"><div class="MuiTypography-root MuiTypography-body1 css-1rc6ywa">部署标准集群</div></div></div></div></div></li><li class="MuiTreeItem-root css-14t19hb" role="treeitem" aria-expanded="false" id="left-nav-treeview-0-5" tabindex="-1" style="margin-top:0.1875rem;margin-bottom:0.1875rem"><div class="css-zfdk9c MuiTreeItem-content" style="width:inherit"><div class="MuiTreeItem-iconContainer"/><div class="MuiTreeItem-label"><div class="css-w8t2sr"><svg class="MuiSvgIcon-root MuiSvgIcon-fontSizeMedium MuiTreeItem-ChevronRightIcon css-hkir54" focusable="false" aria-hidden="true" viewbox="0 0 24 24" data-testid="ChevronRightIcon"><path d="M10 6 8.59 7.41 13.17 12l-4.58 4.59L10 18l6-6z"/></svg><div class="MuiBox-root css-8atqhb"><div class="MuiTypography-root MuiTypography-body1 css-1rc6ywa">数据迁移</div></div></div></div></div></li><li class="MuiTreeItem-root css-14t19hb" role="treeitem" aria-expanded="false" id="left-nav-treeview-0-6" tabindex="-1" style="margin-top:0.1875rem;margin-bottom:0.1875rem"><div class="css-zfdk9c MuiTreeItem-content" style="width:inherit"><div class="MuiTreeItem-iconContainer"/><div class="MuiTreeItem-label"><div class="css-w8t2sr"><svg class="MuiSvgIcon-root MuiSvgIcon-fontSizeMedium MuiTreeItem-ChevronRightIcon css-hkir54" focusable="false" aria-hidden="true" viewbox="0 0 24 24" data-testid="ChevronRightIcon"><path d="M10 6 8.59 7.41 13.17 12l-4.58 4.59L10 18l6-6z"/></svg><div class="MuiBox-root css-8atqhb"><div class="MuiTypography-root MuiTypography-body1 css-1rc6ywa">数据集成</div></div></div></div></div></li><li class="MuiTreeItem-root css-14t19hb" role="treeitem" aria-expanded="false" id="left-nav-treeview-0-7" tabindex="-1" style="margin-top:0.1875rem;margin-bottom:0.1875rem"><div class="css-zfdk9c MuiTreeItem-content" style="width:inherit"><div class="MuiTreeItem-iconContainer"/><div class="MuiTreeItem-label"><div class="css-w8t2sr"><svg class="MuiSvgIcon-root MuiSvgIcon-fontSizeMedium MuiTreeItem-ChevronRightIcon css-hkir54" focusable="false" aria-hidden="true" viewbox="0 0 24 24" data-testid="ChevronRightIcon"><path d="M10 6 8.59 7.41 13.17 12l-4.58 4.59L10 18l6-6z"/></svg><div class="MuiBox-root css-8atqhb"><div class="MuiTypography-root MuiTypography-body1 css-1rc6ywa">运维操作</div></div></div></div></div></li><li class="MuiTreeItem-root css-14t19hb" role="treeitem" aria-expanded="false" id="left-nav-treeview-0-8" tabindex="-1" style="margin-top:0.1875rem;margin-bottom:0.1875rem"><div class="css-zfdk9c MuiTreeItem-content" style="width:inherit"><div class="MuiTreeItem-iconContainer"/><div class="MuiTreeItem-label"><div class="css-w8t2sr"><svg class="MuiSvgIcon-root MuiSvgIcon-fontSizeMedium MuiTreeItem-ChevronRightIcon css-hkir54" focusable="false" aria-hidden="true" viewbox="0 0 24 24" data-testid="ChevronRightIcon"><path d="M10 6 8.59 7.41 13.17 12l-4.58 4.59L10 18l6-6z"/></svg><div class="MuiBox-root css-8atqhb"><div class="MuiTypography-root MuiTypography-body1 css-1rc6ywa">监控与告警</div></div></div></div></div></li><li class="MuiTreeItem-root css-14t19hb" role="treeitem" aria-expanded="false" id="left-nav-treeview-0-9" tabindex="-1" style="margin-top:0.1875rem;margin-bottom:0.1875rem"><div class="css-zfdk9c MuiTreeItem-content" style="width:inherit"><div class="MuiTreeItem-iconContainer"/><div class="MuiTreeItem-label"><div class="css-w8t2sr"><svg class="MuiSvgIcon-root MuiSvgIcon-fontSizeMedium MuiTreeItem-ChevronRightIcon css-hkir54" focusable="false" aria-hidden="true" viewbox="0 0 24 24" data-testid="ChevronRightIcon"><path d="M10 6 8.59 7.41 13.17 12l-4.58 4.59L10 18l6-6z"/></svg><div class="MuiBox-root css-8atqhb"><div class="MuiTypography-root MuiTypography-body1 css-1rc6ywa">故障诊断</div></div></div></div></div></li><li class="MuiTreeItem-root css-14t19hb" role="treeitem" aria-expanded="false" id="left-nav-treeview-0-10" tabindex="-1" style="margin-top:0.1875rem;margin-bottom:0.1875rem"><div class="css-zfdk9c MuiTreeItem-content" style="width:inherit"><div class="MuiTreeItem-iconContainer"/><div class="MuiTreeItem-label"><div class="css-w8t2sr"><svg class="MuiSvgIcon-root MuiSvgIcon-fontSizeMedium MuiTreeItem-ChevronRightIcon css-hkir54" focusable="false" aria-hidden="true" viewbox="0 0 24 24" data-testid="ChevronRightIcon"><path d="M10 6 8.59 7.41 13.17 12l-4.58 4.59L10 18l6-6z"/></svg><div class="MuiBox-root css-8atqhb"><div class="MuiTypography-root MuiTypography-body1 css-1rc6ywa">性能调优</div></div></div></div></div></li><li class="MuiTreeItem-root css-14t19hb" role="treeitem" aria-expanded="false" id="left-nav-treeview-0-11" tabindex="-1" style="margin-top:0.1875rem;margin-bottom:0.1875rem"><div class="css-zfdk9c MuiTreeItem-content" style="width:inherit"><div class="MuiTreeItem-iconContainer"/><div class="MuiTreeItem-label"><div class="css-w8t2sr"><svg class="MuiSvgIcon-root MuiSvgIcon-fontSizeMedium MuiTreeItem-ChevronRightIcon css-hkir54" focusable="false" aria-hidden="true" viewbox="0 0 24 24" data-testid="ChevronRightIcon"><path d="M10 6 8.59 7.41 13.17 12l-4.58 4.59L10 18l6-6z"/></svg><div class="MuiBox-root css-8atqhb"><div class="MuiTypography-root MuiTypography-body1 css-1rc6ywa">教程</div></div></div></div></div></li><li class="MuiTreeItem-root css-14t19hb" role="treeitem" aria-expanded="false" id="left-nav-treeview-0-12" tabindex="-1" style="margin-top:0.1875rem;margin-bottom:0.1875rem"><div class="css-zfdk9c MuiTreeItem-content" style="width:inherit"><div class="MuiTreeItem-iconContainer"/><div class="MuiTreeItem-label"><div class="css-w8t2sr"><svg class="MuiSvgIcon-root MuiSvgIcon-fontSizeMedium MuiTreeItem-ChevronRightIcon css-hkir54" focusable="false" aria-hidden="true" viewbox="0 0 24 24" data-testid="ChevronRightIcon"><path d="M10 6 8.59 7.41 13.17 12l-4.58 4.59L10 18l6-6z"/></svg><div class="MuiBox-root css-8atqhb"><div class="MuiTypography-root MuiTypography-body1 css-1rc6ywa">TiDB 工具</div></div></div></div></div></li><li class="MuiTreeItem-root css-14t19hb" role="treeitem" aria-expanded="false" id="left-nav-treeview-0-13" tabindex="-1" style="margin-top:0.1875rem;margin-bottom:0.1875rem"><div class="css-zfdk9c MuiTreeItem-content" style="width:inherit"><div class="MuiTreeItem-iconContainer"/><div class="MuiTreeItem-label"><div class="css-w8t2sr"><svg class="MuiSvgIcon-root MuiSvgIcon-fontSizeMedium MuiTreeItem-ChevronRightIcon css-hkir54" focusable="false" aria-hidden="true" viewbox="0 0 24 24" data-testid="ChevronRightIcon"><path d="M10 6 8.59 7.41 13.17 12l-4.58 4.59L10 18l6-6z"/></svg><div class="MuiBox-root css-8atqhb"><div class="MuiTypography-root MuiTypography-body1 css-1rc6ywa">参考指南</div></div></div></div></div></li><li class="MuiTreeItem-root css-14t19hb" role="treeitem" aria-expanded="false" id="left-nav-treeview-0-14" tabindex="-1" style="margin-top:0.1875rem;margin-bottom:0.1875rem"><div class="css-zfdk9c MuiTreeItem-content" style="width:inherit"><div class="MuiTreeItem-iconContainer"/><div class="MuiTreeItem-label"><div class="css-w8t2sr"><svg class="MuiSvgIcon-root MuiSvgIcon-fontSizeMedium MuiTreeItem-ChevronRightIcon css-hkir54" focusable="false" aria-hidden="true" viewbox="0 0 24 24" data-testid="ChevronRightIcon"><path d="M10 6 8.59 7.41 13.17 12l-4.58 4.59L10 18l6-6z"/></svg><div class="MuiBox-root css-8atqhb"><div class="MuiTypography-root MuiTypography-body1 css-1rc6ywa">常见问题解答 (FAQ)</div></div></div></div></div></li><li class="MuiTreeItem-root css-14t19hb" role="treeitem" aria-expanded="false" id="left-nav-treeview-0-15" tabindex="-1" style="margin-top:0.1875rem;margin-bottom:0.1875rem"><div class="css-zfdk9c MuiTreeItem-content" style="width:inherit"><div class="MuiTreeItem-iconContainer"/><div class="MuiTreeItem-label"><div class="css-w8t2sr"><svg class="MuiSvgIcon-root MuiSvgIcon-fontSizeMedium MuiTreeItem-ChevronRightIcon css-hkir54" focusable="false" aria-hidden="true" viewbox="0 0 24 24" data-testid="ChevronRightIcon"><path d="M10 6 8.59 7.41 13.17 12l-4.58 4.59L10 18l6-6z"/></svg><div class="MuiBox-root css-8atqhb"><div class="MuiTypography-root MuiTypography-body1 css-1rc6ywa">版本发布历史</div></div></div></div></div></li><a style="text-decoration:none;width:100%;color:inherit" href="/zh/tidb/dev/glossary"><li class="MuiTreeItem-root css-14t19hb" role="treeitem" id="left-nav-treeview-0-16" tabindex="-1" style="margin-top:0.1875rem;margin-bottom:0.1875rem"><div class="css-zfdk9c MuiTreeItem-content" style="width:inherit"><div class="MuiTreeItem-iconContainer"/><div class="MuiTreeItem-label"><div class="css-w8t2sr"><div class="MuiBox-root css-3o0h5k"/><div class="MuiBox-root css-8atqhb"><div class="MuiTypography-root MuiTypography-body1 css-1rc6ywa">术语表</div></div></div></div></div></li></a></ul></div></aside><main class="MuiBox-root css-sb2sd0"><div class="MuiBox-root css-w0vdto"><div class="css-1q5cbag"><div class="MuiBox-root css-was4pq"><div class="MuiContainer-root MuiContainer-maxWidthLg MuiContainer-disableGutters doc-content css-5csqms"><div class="markdown-body MuiBox-root css-0"><h1 id="结果集不稳定" style="position:relative">结果集不稳定<a href="#%E7%BB%93%E6%9E%9C%E9%9B%86%E4%B8%8D%E7%A8%B3%E5%AE%9A" aria-label="结果集不稳定 permalink" class="anchor after"><svg aria-hidden="true" focusable="false" height="16" version="1.1" viewbox="0 0 16 16" width="16"><path fill-rule="evenodd" d="M4 9h1v1H4c-1.5 0-3-1.69-3-3.5S2.55 3 4 3h4c1.45 0 3 1.69 3 3.5 0 1.41-.91 2.72-2 3.25V8.59c.58-.45 1-1.27 1-2.09C10 5.22 8.98 4 8 4H4c-.98 0-2 1.22-2 2.5S3 9 4 9zm9-3h-1v1h1c1 0 2 1.22 2 2.5S13.98 12 13 12H9c-.98 0-2-1.22-2-2.5 0-.83.42-1.64 1-2.09V6.25c-1.09.53-2 1.84-2 3.25C6 11.31 7.55 13 9 13h4c1.45 0 3-1.69 3-3.5S14.5 6 13 6z"/></svg></a></h1><p>本章将叙述结果集不稳定错误的处理办法。</p><h2 id="group-by" style="position:relative">group by<a href="#group-by" aria-label="group by permalink" class="anchor after"><svg aria-hidden="true" focusable="false" height="16" version="1.1" viewbox="0 0 16 16" width="16"><path fill-rule="evenodd" d="M4 9h1v1H4c-1.5 0-3-1.69-3-3.5S2.55 3 4 3h4c1.45 0 3 1.69 3 3.5 0 1.41-.91 2.72-2 3.25V8.59c.58-.45 1-1.27 1-2.09C10 5.22 8.98 4 8 4H4c-.98 0-2 1.22-2 2.5S3 9 4 9zm9-3h-1v1h1c1 0 2 1.22 2 2.5S13.98 12 13 12H9c-.98 0-2-1.22-2-2.5 0-.83.42-1.64 1-2.09V6.25c-1.09.53-2 1.84-2 3.25C6 11.31 7.55 13 9 13h4c1.45 0 3-1.69 3-3.5S14.5 6 13 6z"/></svg></a></h2><p>出于便捷的考量，MySQL “扩展” 了 group by 语法，使 select 子句可以引用未在 group by 子句中声明的非聚集字段，也就是 non-full group by 语法。在其他数据库中，这被认为是一种语法错误，因为这会导致结果集不稳定。</p><p>在下例的 3 条 SQL 语句中，第一条 SQL 使用了 full group by 语法，所有在 select 子句中引用的字段，都在 group by 子句中有所声明，所以它的结果集是稳定的，可以看到 class 与 stuname 的全部组合共有三种；第二条与第三条是同一个 SQL，但它在两次执行时得到了不同的结果，这条 SQL 的 group by 子句中仅声明了一个 class 字段，因此结果集只会针对 class 进行聚集，class 的唯一值有两个，也就是说结果集中只会包含两行数据，而 class 与 stuname 的全部组合共有三种，班级 2018_CS_03 有两位同学，每次执行时返回哪位同学是没有语义上的限制的，都是符合语义的结果。</p><pre><code class="hljs language-sql"><div class="MuiBox-root css-1qhimia">mysql<span class="hljs-operator">&gt;</span> <span class="hljs-keyword">SELECT</span> a.class, a.stuname, <span class="hljs-built_in">max</span>(b.courscore) <span class="hljs-keyword">from</span> stu_info a <span class="hljs-keyword">join</span> stu_score b <span class="hljs-keyword">on</span> a.stuno<span class="hljs-operator">=</span>b.stuno <span class="hljs-keyword">group</span> <span class="hljs-keyword">by</span> a.class, a.stuname <span class="hljs-keyword">order</span> <span class="hljs-keyword">by</span> a.class, a.stuname; <span class="hljs-operator">+</span><span class="hljs-comment">------------+--------------+------------------+</span> <span class="hljs-operator">|</span> class <span class="hljs-operator">|</span> stuname <span class="hljs-operator">|</span> <span class="hljs-built_in">max</span>(b.courscore) <span class="hljs-operator">|</span> <span class="hljs-operator">+</span><span class="hljs-comment">------------+--------------+------------------+</span> <span class="hljs-operator">|</span> <span class="hljs-number">2018</span>_CS_01 <span class="hljs-operator">|</span> MonkeyDLuffy <span class="hljs-operator">|</span> <span class="hljs-number">95.5</span> <span class="hljs-operator">|</span> <span class="hljs-operator">|</span> <span class="hljs-number">2018</span>_CS_03 <span class="hljs-operator">|</span> PatrickStar <span class="hljs-operator">|</span> <span class="hljs-number">99.0</span> <span class="hljs-operator">|</span> <span class="hljs-operator">|</span> <span class="hljs-number">2018</span>_CS_03 <span class="hljs-operator">|</span> SpongeBob <span class="hljs-operator">|</span> <span class="hljs-number">95.0</span> <span class="hljs-operator">|</span> <span class="hljs-operator">+</span><span class="hljs-comment">------------+--------------+------------------+</span> <span class="hljs-number">3</span> <span class="hljs-keyword">rows</span> <span class="hljs-keyword">in</span> <span class="hljs-keyword">set</span> (<span class="hljs-number">0.00</span> sec) mysql<span class="hljs-operator">&gt;</span> <span class="hljs-keyword">select</span> a.class, a.stuname, <span class="hljs-built_in">max</span>(b.courscore) <span class="hljs-keyword">from</span> stu_info a <span class="hljs-keyword">join</span> stu_score b <span class="hljs-keyword">on</span> a.stuno<span class="hljs-operator">=</span>b.stuno <span class="hljs-keyword">group</span> <span class="hljs-keyword">by</span> a.class <span class="hljs-keyword">order</span> <span class="hljs-keyword">by</span> a.class, a.stuname; <span class="hljs-operator">+</span><span class="hljs-comment">------------+--------------+------------------+</span> <span class="hljs-operator">|</span> class <span class="hljs-operator">|</span> stuname <span class="hljs-operator">|</span> <span class="hljs-built_in">max</span>(b.courscore) <span class="hljs-operator">|</span> <span class="hljs-operator">+</span><span class="hljs-comment">------------+--------------+------------------+</span> <span class="hljs-operator">|</span> <span class="hljs-number">2018</span>_CS_01 <span class="hljs-operator">|</span> MonkeyDLuffy <span class="hljs-operator">|</span> <span class="hljs-number">95.5</span> <span class="hljs-operator">|</span> <span class="hljs-operator">|</span> <span class="hljs-number">2018</span>_CS_03 <span class="hljs-operator">|</span> SpongeBob <span class="hljs-operator">|</span> <span class="hljs-number">99.0</span> <span class="hljs-operator">|</span> <span class="hljs-operator">+</span><span class="hljs-comment">------------+--------------+------------------+</span> <span class="hljs-number">2</span> <span class="hljs-keyword">rows</span> <span class="hljs-keyword">in</span> <span class="hljs-keyword">set</span> (<span class="hljs-number">0.01</span> sec) mysql<span class="hljs-operator">&gt;</span> <span class="hljs-keyword">select</span> a.class, a.stuname, <span class="hljs-built_in">max</span>(b.courscore) <span class="hljs-keyword">from</span> stu_info a <span class="hljs-keyword">join</span> stu_score b <span class="hljs-keyword">on</span> a.stuno<span class="hljs-operator">=</span>b.stuno <span class="hljs-keyword">group</span> <span class="hljs-keyword">by</span> a.class <span class="hljs-keyword">order</span> <span class="hljs-keyword">by</span> a.class, a.stuname; <span class="hljs-operator">+</span><span class="hljs-comment">------------+--------------+------------------+</span> <span class="hljs-operator">|</span> class <span class="hljs-operator">|</span> stuname <span class="hljs-operator">|</span> <span class="hljs-built_in">max</span>(b.courscore) <span class="hljs-operator">|</span> <span class="hljs-operator">+</span><span class="hljs-comment">------------+--------------+------------------+</span> <span class="hljs-operator">|</span> <span class="hljs-number">2018</span>_CS_01 <span class="hljs-operator">|</span> MonkeyDLuffy <span class="hljs-operator">|</span> <span class="hljs-number">95.5</span> <span class="hljs-operator">|</span> <span class="hljs-operator">|</span> <span class="hljs-number">2018</span>_CS_03 <span class="hljs-operator">|</span> PatrickStar <span class="hljs-operator">|</span> <span class="hljs-number">99.0</span> <span class="hljs-operator">|</span> <span class="hljs-operator">+</span><span class="hljs-comment">------------+--------------+------------------+</span> <span class="hljs-number">2</span> <span class="hljs-keyword">rows</span> <span class="hljs-keyword">in</span> <span class="hljs-keyword">set</span> (<span class="hljs-number">0.01</span> sec) </div><button class="MuiButtonBase-root MuiIconButton-root MuiIconButton-sizeSmall css-1rmx1rm" tabindex="0" type="button" aria-label="Toggle code wrap"><svg class="MuiSvgIcon-root MuiSvgIcon-fontSizeInherit css-1cw4hi4" focusable="false" aria-hidden="true" viewbox="0 0 24 24" data-testid="WrapTextIcon"><path d="M4 19h6v-2H4v2zM20 5H4v2h16V5zm-3 6H4v2h13.25c1.1 0 2 .9 2 2s-.9 2-2 2H15v-2l-3 3 3 3v-2h2c2.21 0 4-1.79 4-4s-1.79-4-4-4z"/></svg></button><button class="MuiButtonBase-root MuiIconButton-root MuiIconButton-sizeSmall css-fxo539" tabindex="0" type="button" aria-label="copy"><svg class="MuiSvgIcon-root MuiSvgIcon-fontSizeInherit css-1cw4hi4" focusable="false" aria-hidden="true" viewbox="0 0 24 24" data-testid="ContentCopyIcon"><path d="M16 1H4c-1.1 0-2 .9-2 2v14h2V3h12V1zm3 4H8c-1.1 0-2 .9-2 2v14c0 1.1.9 2 2 2h11c1.1 0 2-.9 2-2V7c0-1.1-.9-2-2-2zm0 16H8V7h11v14z"/></svg></button></code></pre><p>因此，想保障 group by 语句结果集的稳定，请使用 full group by 语法。</p><p>MySQL 提供了一个 SQL_MODE 开关 ONLY_FULL_GROUP_BY 来控制是否进行 full group by 语法的检查，TiDB 也兼容了这个 SQL_MODE 开关：</p><pre><code class="hljs language-sql"><div class="MuiBox-root css-1qhimia">mysql<span class="hljs-operator">&gt;</span> <span class="hljs-keyword">select</span> a.class, a.stuname, <span class="hljs-built_in">max</span>(b.courscore) <span class="hljs-keyword">from</span> stu_info a <span class="hljs-keyword">join</span> stu_score b <span class="hljs-keyword">on</span> a.stuno<span class="hljs-operator">=</span>b.stuno <span class="hljs-keyword">group</span> <span class="hljs-keyword">by</span> a.class <span class="hljs-keyword">order</span> <span class="hljs-keyword">by</span> a.class, a.stuname; <span class="hljs-operator">+</span><span class="hljs-comment">------------+--------------+------------------+</span> <span class="hljs-operator">|</span> class <span class="hljs-operator">|</span> stuname <span class="hljs-operator">|</span> <span class="hljs-built_in">max</span>(b.courscore) <span class="hljs-operator">|</span> <span class="hljs-operator">+</span><span class="hljs-comment">------------+--------------+------------------+</span> <span class="hljs-operator">|</span> <span class="hljs-number">2018</span>_CS_01 <span class="hljs-operator">|</span> MonkeyDLuffy <span class="hljs-operator">|</span> <span class="hljs-number">95.5</span> <span class="hljs-operator">|</span> <span class="hljs-operator">|</span> <span class="hljs-number">2018</span>_CS_03 <span class="hljs-operator">|</span> PatrickStar <span class="hljs-operator">|</span> <span class="hljs-number">99.0</span> <span class="hljs-operator">|</span> <span class="hljs-operator">+</span><span class="hljs-comment">------------+--------------+------------------+</span> <span class="hljs-number">2</span> <span class="hljs-keyword">rows</span> <span class="hljs-keyword">in</span> <span class="hljs-keyword">set</span> (<span class="hljs-number">0.01</span> sec) mysql<span class="hljs-operator">&gt;</span> <span class="hljs-keyword">set</span> @<span class="hljs-variable">@sql</span>_mode<span class="hljs-operator">=</span><span class="hljs-string">'STRICT_TRANS_TABLES,NO_ENGINE_SUBSTITUTION,ONLY_FULL_GROUP_BY'</span>; Query OK, <span class="hljs-number">0</span> <span class="hljs-keyword">rows</span> affected (<span class="hljs-number">0.01</span> sec) mysql<span class="hljs-operator">&gt;</span> <span class="hljs-keyword">select</span> a.class, a.stuname, <span class="hljs-built_in">max</span>(b.courscore) <span class="hljs-keyword">from</span> stu_info a <span class="hljs-keyword">join</span> stu_score b <span class="hljs-keyword">on</span> a.stuno<span class="hljs-operator">=</span>b.stuno <span class="hljs-keyword">group</span> <span class="hljs-keyword">by</span> a.class <span class="hljs-keyword">order</span> <span class="hljs-keyword">by</span> a.class, a.stuname; ERROR <span class="hljs-number">1055</span> (<span class="hljs-number">42000</span>): Expression #<span class="hljs-number">2</span> <span class="hljs-keyword">of</span> <span class="hljs-keyword">ORDER</span> <span class="hljs-keyword">BY</span> <span class="hljs-keyword">is</span> <span class="hljs-keyword">not</span> <span class="hljs-keyword">in</span> <span class="hljs-keyword">GROUP</span> <span class="hljs-keyword">BY</span> clause <span class="hljs-keyword">and</span> <span class="hljs-keyword">contains</span> nonaggregated <span class="hljs-keyword">column</span> <span class="hljs-string">''</span> which <span class="hljs-keyword">is</span> <span class="hljs-keyword">not</span> functionally dependent <span class="hljs-keyword">on</span> columns <span class="hljs-keyword">in</span> <span class="hljs-keyword">GROUP</span> <span class="hljs-keyword">BY</span> clause; this <span class="hljs-keyword">is</span> incompatible <span class="hljs-keyword">with</span> sql_mode<span class="hljs-operator">=</span>only_full_group_by </div><button class="MuiButtonBase-root MuiIconButton-root MuiIconButton-sizeSmall css-1rmx1rm" tabindex="0" type="button" aria-label="Toggle code wrap"><svg class="MuiSvgIcon-root MuiSvgIcon-fontSizeInherit css-1cw4hi4" focusable="false" aria-hidden="true" viewbox="0 0 24 24" data-testid="WrapTextIcon"><path d="M4 19h6v-2H4v2zM20 5H4v2h16V5zm-3 6H4v2h13.25c1.1 0 2 .9 2 2s-.9 2-2 2H15v-2l-3 3 3 3v-2h2c2.21 0 4-1.79 4-4s-1.79-4-4-4z"/></svg></button><button class="MuiButtonBase-root MuiIconButton-root MuiIconButton-sizeSmall css-fxo539" tabindex="0" type="button" aria-label="copy"><svg class="MuiSvgIcon-root MuiSvgIcon-fontSizeInherit css-1cw4hi4" focusable="false" aria-hidden="true" viewbox="0 0 24 24" data-testid="ContentCopyIcon"><path d="M16 1H4c-1.1 0-2 .9-2 2v14h2V3h12V1zm3 4H8c-1.1 0-2 .9-2 2v14c0 1.1.9 2 2 2h11c1.1 0 2-.9 2-2V7c0-1.1-.9-2-2-2zm0 16H8V7h11v14z"/></svg></button></code></pre><p><strong>运行结果简述</strong>：上例为 sql_mode 设置了 ONLY_FULL_GROUP_BY 的效果。</p><h2 id="order-by" style="position:relative">order by<a href="#order-by" aria-label="order by permalink" class="anchor after"><svg aria-hidden="true" focusable="false" height="16" version="1.1" viewbox="0 0 16 16" width="16"><path fill-rule="evenodd" d="M4 9h1v1H4c-1.5 0-3-1.69-3-3.5S2.55 3 4 3h4c1.45 0 3 1.69 3 3.5 0 1.41-.91 2.72-2 3.25V8.59c.58-.45 1-1.27 1-2.09C10 5.22 8.98 4 8 4H4c-.98 0-2 1.22-2 2.5S3 9 4 9zm9-3h-1v1h1c1 0 2 1.22 2 2.5S13.98 12 13 12H9c-.98 0-2-1.22-2-2.5 0-.83.42-1.64 1-2.09V6.25c-1.09.53-2 1.84-2 3.25C6 11.31 7.55 13 9 13h4c1.45 0 3-1.69 3-3.5S14.5 6 13 6z"/></svg></a></h2><p>在 SQL 的语义中，只有使用了 order by 语法才会保障结果集的顺序输出。而单机数据库由于数据都存储在一台服务器上，在不进行数据重组时，多次执行的结果往往是稳定的，有些数据库(尤其是 MySQL InnoDB 存储引擎)还会按照主键或索引的顺序进行结果集的输出。TiDB 是分布式数据库，数据被存储在多台服务器上，另外 TiDB 层不缓存数据页，因此不含 order by 的 SQL 语句的结果集展现顺序容易被感知到不稳定。想要按顺序输出的结果集，需明确地把要排序的字段添加到 order by 子句中，这符合 SQL 的语义。</p><p>在下面的案例中，用户只在 order by 子句中添加了一个字段，TiDB 只会按照这一个字段进行排序。</p><pre><code class="hljs language-sql"><div class="MuiBox-root css-1qhimia">mysql<span class="hljs-operator">&gt;</span> <span class="hljs-keyword">select</span> a.class, a.stuname, b.course, b.courscore <span class="hljs-keyword">from</span> stu_info a <span class="hljs-keyword">join</span> stu_score b <span class="hljs-keyword">on</span> a.stuno<span class="hljs-operator">=</span>b.stuno <span class="hljs-keyword">order</span> <span class="hljs-keyword">by</span> a.class; <span class="hljs-operator">+</span><span class="hljs-comment">------------+--------------+-------------------------+-----------+</span> <span class="hljs-operator">|</span> class <span class="hljs-operator">|</span> stuname <span class="hljs-operator">|</span> course <span class="hljs-operator">|</span> courscore <span class="hljs-operator">|</span> <span class="hljs-operator">+</span><span class="hljs-comment">------------+--------------+-------------------------+-----------+</span> <span class="hljs-operator">|</span> <span class="hljs-number">2018</span>_CS_01 <span class="hljs-operator">|</span> MonkeyDLuffy <span class="hljs-operator">|</span> PrinciplesofDatabase <span class="hljs-operator">|</span> <span class="hljs-number">60.5</span> <span class="hljs-operator">|</span> <span class="hljs-operator">|</span> <span class="hljs-number">2018</span>_CS_01 <span class="hljs-operator">|</span> MonkeyDLuffy <span class="hljs-operator">|</span> English <span class="hljs-operator">|</span> <span class="hljs-number">43.0</span> <span class="hljs-operator">|</span> <span class="hljs-operator">|</span> <span class="hljs-number">2018</span>_CS_01 <span class="hljs-operator">|</span> MonkeyDLuffy <span class="hljs-operator">|</span> OpSwimming <span class="hljs-operator">|</span> <span class="hljs-number">67.0</span> <span class="hljs-operator">|</span> <span class="hljs-operator">|</span> <span class="hljs-number">2018</span>_CS_01 <span class="hljs-operator">|</span> MonkeyDLuffy <span class="hljs-operator">|</span> OpFencing <span class="hljs-operator">|</span> <span class="hljs-number">76.0</span> <span class="hljs-operator">|</span> <span class="hljs-operator">|</span> <span class="hljs-number">2018</span>_CS_01 <span class="hljs-operator">|</span> MonkeyDLuffy <span class="hljs-operator">|</span> FundamentalsofCompiling <span class="hljs-operator">|</span> <span class="hljs-number">88.0</span> <span class="hljs-operator">|</span> <span class="hljs-operator">|</span> <span class="hljs-number">2018</span>_CS_01 <span class="hljs-operator">|</span> MonkeyDLuffy <span class="hljs-operator">|</span> OperatingSystem <span class="hljs-operator">|</span> <span class="hljs-number">90.5</span> <span class="hljs-operator">|</span> <span class="hljs-operator">|</span> <span class="hljs-number">2018</span>_CS_01 <span class="hljs-operator">|</span> MonkeyDLuffy <span class="hljs-operator">|</span> PrincipleofStatistics <span class="hljs-operator">|</span> <span class="hljs-number">69.0</span> <span class="hljs-operator">|</span> <span class="hljs-operator">|</span> <span class="hljs-number">2018</span>_CS_01 <span class="hljs-operator">|</span> MonkeyDLuffy <span class="hljs-operator">|</span> ProbabilityTheory <span class="hljs-operator">|</span> <span class="hljs-number">76.0</span> <span class="hljs-operator">|</span> <span class="hljs-operator">|</span> <span class="hljs-number">2018</span>_CS_01 <span class="hljs-operator">|</span> MonkeyDLuffy <span class="hljs-operator">|</span> Physics <span class="hljs-operator">|</span> <span class="hljs-number">63.5</span> <span class="hljs-operator">|</span> <span class="hljs-operator">|</span> <span class="hljs-number">2018</span>_CS_01 <span class="hljs-operator">|</span> MonkeyDLuffy <span class="hljs-operator">|</span> AdvancedMathematics <span class="hljs-operator">|</span> <span class="hljs-number">95.5</span> <span class="hljs-operator">|</span> <span class="hljs-operator">|</span> <span class="hljs-number">2018</span>_CS_01 <span class="hljs-operator">|</span> MonkeyDLuffy <span class="hljs-operator">|</span> LinearAlgebra <span class="hljs-operator">|</span> <span class="hljs-number">92.5</span> <span class="hljs-operator">|</span> <span class="hljs-operator">|</span> <span class="hljs-number">2018</span>_CS_01 <span class="hljs-operator">|</span> MonkeyDLuffy <span class="hljs-operator">|</span> DiscreteMathematics <span class="hljs-operator">|</span> <span class="hljs-number">89.0</span> <span class="hljs-operator">|</span> <span class="hljs-operator">|</span> <span class="hljs-number">2018</span>_CS_03 <span class="hljs-operator">|</span> SpongeBob <span class="hljs-operator">|</span> PrinciplesofDatabase <span class="hljs-operator">|</span> <span class="hljs-number">88.0</span> <span class="hljs-operator">|</span> <span class="hljs-operator">|</span> <span class="hljs-number">2018</span>_CS_03 <span class="hljs-operator">|</span> SpongeBob <span class="hljs-operator">|</span> English <span class="hljs-operator">|</span> <span class="hljs-number">79.0</span> <span class="hljs-operator">|</span> <span class="hljs-operator">|</span> <span class="hljs-number">2018</span>_CS_03 <span class="hljs-operator">|</span> SpongeBob <span class="hljs-operator">|</span> OpBasketball <span class="hljs-operator">|</span> <span class="hljs-number">92.0</span> <span class="hljs-operator">|</span> <span class="hljs-operator">|</span> <span class="hljs-number">2018</span>_CS_03 <span class="hljs-operator">|</span> SpongeBob <span class="hljs-operator">|</span> OpTennis <span class="hljs-operator">|</span> <span class="hljs-number">94.0</span> <span class="hljs-operator">|</span> <span class="hljs-operator">|</span> <span class="hljs-number">2018</span>_CS_03 <span class="hljs-operator">|</span> PatrickStar <span class="hljs-operator">|</span> LinearAlgebra <span class="hljs-operator">|</span> <span class="hljs-number">6.5</span> <span class="hljs-operator">|</span> <span class="hljs-operator">|</span> <span class="hljs-number">2018</span>_CS_03 <span class="hljs-operator">|</span> PatrickStar <span class="hljs-operator">|</span> AdvancedMathematics <span class="hljs-operator">|</span> <span class="hljs-number">5.0</span> <span class="hljs-operator">|</span> <span class="hljs-operator">|</span> <span class="hljs-number">2018</span>_CS_03 <span class="hljs-operator">|</span> SpongeBob <span class="hljs-operator">|</span> DiscreteMathematics <span class="hljs-operator">|</span> <span class="hljs-number">72.0</span> <span class="hljs-operator">|</span> <span class="hljs-operator">|</span> <span class="hljs-number">2018</span>_CS_03 <span class="hljs-operator">|</span> PatrickStar <span class="hljs-operator">|</span> ProbabilityTheory <span class="hljs-operator">|</span> <span class="hljs-number">12.0</span> <span class="hljs-operator">|</span> <span class="hljs-operator">|</span> <span class="hljs-number">2018</span>_CS_03 <span class="hljs-operator">|</span> PatrickStar <span class="hljs-operator">|</span> PrincipleofStatistics <span class="hljs-operator">|</span> <span class="hljs-number">20.0</span> <span class="hljs-operator">|</span> <span class="hljs-operator">|</span> <span class="hljs-number">2018</span>_CS_03 <span class="hljs-operator">|</span> PatrickStar <span class="hljs-operator">|</span> OperatingSystem <span class="hljs-operator">|</span> <span class="hljs-number">36.0</span> <span class="hljs-operator">|</span> <span class="hljs-operator">|</span> <span class="hljs-number">2018</span>_CS_03 <span class="hljs-operator">|</span> PatrickStar <span class="hljs-operator">|</span> FundamentalsofCompiling <span class="hljs-operator">|</span> <span class="hljs-number">2.0</span> <span class="hljs-operator">|</span> <span class="hljs-operator">|</span> <span class="hljs-number">2018</span>_CS_03 <span class="hljs-operator">|</span> PatrickStar <span class="hljs-operator">|</span> DiscreteMathematics <span class="hljs-operator">|</span> <span class="hljs-number">14.0</span> <span class="hljs-operator">|</span> <span class="hljs-operator">|</span> <span class="hljs-number">2018</span>_CS_03 <span class="hljs-operator">|</span> PatrickStar <span class="hljs-operator">|</span> PrinciplesofDatabase <span class="hljs-operator">|</span> <span class="hljs-number">9.0</span> <span class="hljs-operator">|</span> <span class="hljs-operator">|</span> <span class="hljs-number">2018</span>_CS_03 <span class="hljs-operator">|</span> PatrickStar <span class="hljs-operator">|</span> English <span class="hljs-operator">|</span> <span class="hljs-number">60.0</span> <span class="hljs-operator">|</span> <span class="hljs-operator">|</span> <span class="hljs-number">2018</span>_CS_03 <span class="hljs-operator">|</span> PatrickStar <span class="hljs-operator">|</span> OpTableTennis <span class="hljs-operator">|</span> <span class="hljs-number">12.0</span> <span class="hljs-operator">|</span> <span class="hljs-operator">|</span> <span class="hljs-number">2018</span>_CS_03 <span class="hljs-operator">|</span> PatrickStar <span class="hljs-operator">|</span> OpPiano <span class="hljs-operator">|</span> <span class="hljs-number">99.0</span> <span class="hljs-operator">|</span> <span class="hljs-operator">|</span> <span class="hljs-number">2018</span>_CS_03 <span class="hljs-operator">|</span> SpongeBob <span class="hljs-operator">|</span> FundamentalsofCompiling <span class="hljs-operator">|</span> <span class="hljs-number">43.0</span> <span class="hljs-operator">|</span> <span class="hljs-operator">|</span> <span class="hljs-number">2018</span>_CS_03 <span class="hljs-operator">|</span> SpongeBob <span class="hljs-operator">|</span> OperatingSystem <span class="hljs-operator">|</span> <span class="hljs-number">95.0</span> <span class="hljs-operator">|</span> <span class="hljs-operator">|</span> <span class="hljs-number">2018</span>_CS_03 <span class="hljs-operator">|</span> SpongeBob <span class="hljs-operator">|</span> PrincipleofStatistics <span class="hljs-operator">|</span> <span class="hljs-number">90.0</span> <span class="hljs-operator">|</span> <span class="hljs-operator">|</span> <span class="hljs-number">2018</span>_CS_03 <span class="hljs-operator">|</span> SpongeBob <span class="hljs-operator">|</span> ProbabilityTheory <span class="hljs-operator">|</span> <span class="hljs-number">87.0</span> <span class="hljs-operator">|</span> <span class="hljs-operator">|</span> <span class="hljs-number">2018</span>_CS_03 <span class="hljs-operator">|</span> SpongeBob <span class="hljs-operator">|</span> Physics <span class="hljs-operator">|</span> <span class="hljs-number">65.0</span> <span class="hljs-operator">|</span> <span class="hljs-operator">|</span> <span class="hljs-number">2018</span>_CS_03 <span class="hljs-operator">|</span> SpongeBob <span class="hljs-operator">|</span> AdvancedMathematics <span class="hljs-operator">|</span> <span class="hljs-number">55.0</span> <span class="hljs-operator">|</span> <span class="hljs-operator">|</span> <span class="hljs-number">2018</span>_CS_03 <span class="hljs-operator">|</span> SpongeBob <span class="hljs-operator">|</span> LinearAlgebra <span class="hljs-operator">|</span> <span class="hljs-number">60.5</span> <span class="hljs-operator">|</span> <span class="hljs-operator">|</span> <span class="hljs-number">2018</span>_CS_03 <span class="hljs-operator">|</span> PatrickStar <span class="hljs-operator">|</span> Physics <span class="hljs-operator">|</span> <span class="hljs-number">6.0</span> <span class="hljs-operator">|</span> <span class="hljs-operator">+</span><span class="hljs-comment">------------+--------------+-------------------------+-----------+</span> <span class="hljs-number">36</span> <span class="hljs-keyword">rows</span> <span class="hljs-keyword">in</span> <span class="hljs-keyword">set</span> (<span class="hljs-number">0.01</span> sec) </div><button class="MuiButtonBase-root MuiIconButton-root MuiIconButton-sizeSmall css-1rmx1rm" tabindex="0" type="button" aria-label="Toggle code wrap"><svg class="MuiSvgIcon-root MuiSvgIcon-fontSizeInherit css-1cw4hi4" focusable="false" aria-hidden="true" viewbox="0 0 24 24" data-testid="WrapTextIcon"><path d="M4 19h6v-2H4v2zM20 5H4v2h16V5zm-3 6H4v2h13.25c1.1 0 2 .9 2 2s-.9 2-2 2H15v-2l-3 3 3 3v-2h2c2.21 0 4-1.79 4-4s-1.79-4-4-4z"/></svg></button><button class="MuiButtonBase-root MuiIconButton-root MuiIconButton-sizeSmall css-fxo539" tabindex="0" type="button" aria-label="copy"><svg class="MuiSvgIcon-root MuiSvgIcon-fontSizeInherit css-1cw4hi4" focusable="false" aria-hidden="true" viewbox="0 0 24 24" data-testid="ContentCopyIcon"><path d="M16 1H4c-1.1 0-2 .9-2 2v14h2V3h12V1zm3 4H8c-1.1 0-2 .9-2 2v14c0 1.1.9 2 2 2h11c1.1 0 2-.9 2-2V7c0-1.1-.9-2-2-2zm0 16H8V7h11v14z"/></svg></button></code></pre><p>当遇到相同的 order by 值时，排序结果不稳定。为减少随机性，应当尽可能保持 order by 值的唯一性。不能保证唯一的继续加，保证 order by 的字段组合是唯一时，结果才能唯一。</p><h2 id="由于-group_concat-中没有使用-order-by-导致结果集不稳定" style="position:relative">由于 group_concat() 中没有使用 order by 导致结果集不稳定<a href="#%E7%94%B1%E4%BA%8E-group_concat-%E4%B8%AD%E6%B2%A1%E6%9C%89%E4%BD%BF%E7%94%A8-order-by-%E5%AF%BC%E8%87%B4%E7%BB%93%E6%9E%9C%E9%9B%86%E4%B8%8D%E7%A8%B3%E5%AE%9A" aria-label="由于 group_concat 中没有使用 order by 导致结果集不稳定 permalink" class="anchor after"><svg aria-hidden="true" focusable="false" height="16" version="1.1" viewbox="0 0 16 16" width="16"><path fill-rule="evenodd" d="M4 9h1v1H4c-1.5 0-3-1.69-3-3.5S2.55 3 4 3h4c1.45 0 3 1.69 3 3.5 0 1.41-.91 2.72-2 3.25V8.59c.58-.45 1-1.27 1-2.09C10 5.22 8.98 4 8 4H4c-.98 0-2 1.22-2 2.5S3 9 4 9zm9-3h-1v1h1c1 0 2 1.22 2 2.5S13.98 12 13 12H9c-.98 0-2-1.22-2-2.5 0-.83.42-1.64 1-2.09V6.25c-1.09.53-2 1.84-2 3.25C6 11.31 7.55 13 9 13h4c1.45 0 3-1.69 3-3.5S14.5 6 13 6z"/></svg></a></h2><p>结果集不稳定是因为 TiDB 是并行地从存储层读取数据，所以 <code>group_concat()</code> 在不加 order by 的情况下得到的结果集展现顺序容易被感知到不稳定。</p><p><code>group_concat()</code> 要获取到按顺序输出的结果集，需要把用于排序的字段添加到 order by 子句中，这样才符合 SQL 的语义。在下面的案例中，使用 <code>group_concat()</code> 不加 order by 的情况下拼接 customer_id，造成结果集不稳定：</p><ol><li><p>不加 order by</p><p>第一次查询：</p><pre><code class="hljs language-sql"><div class="MuiBox-root css-1qhimia">mysql<span class="hljs-operator">&gt;</span> <span class="hljs-keyword">select</span> GROUP_CONCAT( customer_id SEPARATOR <span class="hljs-string">','</span> ) <span class="hljs-keyword">FROM</span> customer <span class="hljs-keyword">where</span> customer_id <span class="hljs-keyword">like</span> <span class="hljs-string">'200002%'</span>; <span class="hljs-operator">+</span><span class="hljs-comment">-------------------------------------------------------------------------+</span> <span class="hljs-operator">|</span> GROUP_CONCAT(customer_id SEPARATOR <span class="hljs-string">','</span>) <span class="hljs-operator">|</span> <span class="hljs-operator">+</span><span class="hljs-comment">-------------------------------------------------------------------------+</span> <span class="hljs-operator">|</span> <span class="hljs-number">20000200992</span>,<span class="hljs-number">20000200993</span>,<span class="hljs-number">20000200994</span>,<span class="hljs-number">20000200995</span>,<span class="hljs-number">20000200996</span>,<span class="hljs-number">20000200.</span>.. <span class="hljs-operator">|</span> <span class="hljs-operator">+</span><span class="hljs-comment">-------------------------------------------------------------------------+</span> </div><button class="MuiButtonBase-root MuiIconButton-root MuiIconButton-sizeSmall css-1rmx1rm" tabindex="0" type="button" aria-label="Toggle code wrap"><svg class="MuiSvgIcon-root MuiSvgIcon-fontSizeInherit css-1cw4hi4" focusable="false" aria-hidden="true" viewbox="0 0 24 24" data-testid="WrapTextIcon"><path d="M4 19h6v-2H4v2zM20 5H4v2h16V5zm-3 6H4v2h13.25c1.1 0 2 .9 2 2s-.9 2-2 2H15v-2l-3 3 3 3v-2h2c2.21 0 4-1.79 4-4s-1.79-4-4-4z"/></svg></button><button class="MuiButtonBase-root MuiIconButton-root MuiIconButton-sizeSmall css-fxo539" tabindex="0" type="button" aria-label="copy"><svg class="MuiSvgIcon-root MuiSvgIcon-fontSizeInherit css-1cw4hi4" focusable="false" aria-hidden="true" viewbox="0 0 24 24" data-testid="ContentCopyIcon"><path d="M16 1H4c-1.1 0-2 .9-2 2v14h2V3h12V1zm3 4H8c-1.1 0-2 .9-2 2v14c0 1.1.9 2 2 2h11c1.1 0 2-.9 2-2V7c0-1.1-.9-2-2-2zm0 16H8V7h11v14z"/></svg></button></code></pre><p>第二次查询：</p><pre><code class="hljs language-sql"><div class="MuiBox-root css-1qhimia">mysql<span class="hljs-operator">&gt;</span> <span class="hljs-keyword">select</span> GROUP_CONCAT( customer_id SEPARATOR <span class="hljs-string">','</span> ) <span class="hljs-keyword">FROM</span> customer <span class="hljs-keyword">where</span> customer_id <span class="hljs-keyword">like</span> <span class="hljs-string">'200002%'</span>; <span class="hljs-operator">+</span><span class="hljs-comment">-------------------------------------------------------------------------+</span> <span class="hljs-operator">|</span> GROUP_CONCAT(customer_id SEPARATOR <span class="hljs-string">','</span>) <span class="hljs-operator">|</span> <span class="hljs-operator">+</span><span class="hljs-comment">-------------------------------------------------------------------------+</span> <span class="hljs-operator">|</span> <span class="hljs-number">20000203040</span>,<span class="hljs-number">20000203041</span>,<span class="hljs-number">20000203042</span>,<span class="hljs-number">20000203043</span>,<span class="hljs-number">20000203044</span>,<span class="hljs-number">20000203.</span>.. <span class="hljs-operator">|</span> <span class="hljs-operator">+</span><span class="hljs-comment">-------------------------------------------------------------------------+</span> </div><button class="MuiButtonBase-root MuiIconButton-root MuiIconButton-sizeSmall css-1rmx1rm" tabindex="0" type="button" aria-label="Toggle code wrap"><svg class="MuiSvgIcon-root MuiSvgIcon-fontSizeInherit css-1cw4hi4" focusable="false" aria-hidden="true" viewbox="0 0 24 24" data-testid="WrapTextIcon"><path d="M4 19h6v-2H4v2zM20 5H4v2h16V5zm-3 6H4v2h13.25c1.1 0 2 .9 2 2s-.9 2-2 2H15v-2l-3 3 3 3v-2h2c2.21 0 4-1.79 4-4s-1.79-4-4-4z"/></svg></button><button class="MuiButtonBase-root MuiIconButton-root MuiIconButton-sizeSmall css-fxo539" tabindex="0" type="button" aria-label="copy"><svg class="MuiSvgIcon-root MuiSvgIcon-fontSizeInherit css-1cw4hi4" focusable="false" aria-hidden="true" viewbox="0 0 24 24" data-testid="ContentCopyIcon"><path d="M16 1H4c-1.1 0-2 .9-2 2v14h2V3h12V1zm3 4H8c-1.1 0-2 .9-2 2v14c0 1.1.9 2 2 2h11c1.1 0 2-.9 2-2V7c0-1.1-.9-2-2-2zm0 16H8V7h11v14z"/></svg></button></code></pre></li><li><p>加 order by</p><p>第一次查询：</p><pre><code class="hljs language-sql"><div class="MuiBox-root css-1qhimia">mysql<span class="hljs-operator">&gt;</span> <span class="hljs-keyword">select</span> GROUP_CONCAT( customer_id <span class="hljs-keyword">order</span> <span class="hljs-keyword">by</span> customer_id SEPARATOR <span class="hljs-string">','</span> ) <span class="hljs-keyword">FROM</span> customer <span class="hljs-keyword">where</span> customer_id <span class="hljs-keyword">like</span> <span class="hljs-string">'200002%'</span>; <span class="hljs-operator">+</span><span class="hljs-comment">-------------------------------------------------------------------------+</span> <span class="hljs-operator">|</span> GROUP_CONCAT(customer_id SEPARATOR <span class="hljs-string">','</span>) <span class="hljs-operator">|</span> <span class="hljs-operator">+</span><span class="hljs-comment">-------------------------------------------------------------------------+</span> <span class="hljs-operator">|</span> <span class="hljs-number">20000200000</span>,<span class="hljs-number">20000200001</span>,<span class="hljs-number">20000200002</span>,<span class="hljs-number">20000200003</span>,<span class="hljs-number">20000200004</span>,<span class="hljs-number">20000200.</span>.. <span class="hljs-operator">|</span> <span class="hljs-operator">+</span><span class="hljs-comment">-------------------------------------------------------------------------+</span> </div><button class="MuiButtonBase-root MuiIconButton-root MuiIconButton-sizeSmall css-1rmx1rm" tabindex="0" type="button" aria-label="Toggle code wrap"><svg class="MuiSvgIcon-root MuiSvgIcon-fontSizeInherit css-1cw4hi4" focusable="false" aria-hidden="true" viewbox="0 0 24 24" data-testid="WrapTextIcon"><path d="M4 19h6v-2H4v2zM20 5H4v2h16V5zm-3 6H4v2h13.25c1.1 0 2 .9 2 2s-.9 2-2 2H15v-2l-3 3 3 3v-2h2c2.21 0 4-1.79 4-4s-1.79-4-4-4z"/></svg></button><button class="MuiButtonBase-root MuiIconButton-root MuiIconButton-sizeSmall css-fxo539" tabindex="0" type="button" aria-label="copy"><svg class="MuiSvgIcon-root MuiSvgIcon-fontSizeInherit css-1cw4hi4" focusable="false" aria-hidden="true" viewbox="0 0 24 24" data-testid="ContentCopyIcon"><path d="M16 1H4c-1.1 0-2 .9-2 2v14h2V3h12V1zm3 4H8c-1.1 0-2 .9-2 2v14c0 1.1.9 2 2 2h11c1.1 0 2-.9 2-2V7c0-1.1-.9-2-2-2zm0 16H8V7h11v14z"/></svg></button></code></pre><p>第二次查询：</p><pre><code class="hljs language-sql"><div class="MuiBox-root css-1qhimia">mysql<span class="hljs-operator">&gt;</span> <span class="hljs-keyword">select</span> GROUP_CONCAT( customer_id <span class="hljs-keyword">order</span> <span class="hljs-keyword">by</span> customer_id SEPARATOR <span class="hljs-string">','</span> ) <span class="hljs-keyword">FROM</span> customer <span class="hljs-keyword">where</span> customer_id <span class="hljs-keyword">like</span> <span class="hljs-string">'200002%'</span>;