<!DOCTYPE html>
<html lang="zh-CN">
  <head>
    <meta charset="utf-8">
    <meta name="viewport" content="width=device-width,initial-scale=1">
    <title> </title>
    <meta name="generator" content="VuePress 1.8.2">
    <link rel="icon" href="/favicon.ico">
    <meta name="description" content=" ">
    <meta name="Description" content="Apache IoTDB: Time Series Database for IoT">
    <meta name="Keywords" content="TSDB, time series, time series database, IoTDB, IoT database, IoT data management,时序数据库, 时间序列管理, IoTDB, 物联网数据库, 实时数据库, 物联网数据管理, 物联网数据">
    <meta name="baidu-site-verification" content="wfKETzB3OT">
    <meta name="google-site-verification" content="mZWAoRY0yj_HAr-s47zHCGHzx5Ju-RVm5wDbPnwQYFo">
    
    <link rel="preload" href="/assets/css/0.styles.ccadf850.css" as="style"><link rel="preload" href="/assets/js/app.c6d1c98c.js" as="script"><link rel="preload" href="/assets/js/3.e95317f3.js" as="script"><link rel="preload" href="/assets/js/346.c6b949d6.js" as="script"><link rel="prefetch" href="/assets/js/10.77e7d27b.js"><link rel="prefetch" href="/assets/js/100.d9eb93c0.js"><link rel="prefetch" href="/assets/js/101.5104776d.js"><link rel="prefetch" href="/assets/js/102.0ee52bfe.js"><link rel="prefetch" href="/assets/js/103.d96ffb14.js"><link rel="prefetch" href="/assets/js/104.1e77d4e7.js"><link rel="prefetch" href="/assets/js/105.cccf9779.js"><link rel="prefetch" href="/assets/js/106.f164036b.js"><link rel="prefetch" href="/assets/js/107.13747c18.js"><link rel="prefetch" href="/assets/js/108.b66c9a8f.js"><link rel="prefetch" href="/assets/js/109.4dff92b4.js"><link rel="prefetch" href="/assets/js/11.242ea813.js"><link rel="prefetch" href="/assets/js/110.3bee101b.js"><link rel="prefetch" href="/assets/js/111.03fb1ee4.js"><link rel="prefetch" href="/assets/js/112.f3812269.js"><link rel="prefetch" href="/assets/js/113.0998cab5.js"><link rel="prefetch" href="/assets/js/114.475c17a1.js"><link rel="prefetch" href="/assets/js/115.e5c1d17e.js"><link rel="prefetch" href="/assets/js/116.1cab9f05.js"><link rel="prefetch" href="/assets/js/117.bb744034.js"><link rel="prefetch" href="/assets/js/118.a42ab86c.js"><link rel="prefetch" href="/assets/js/119.2281328b.js"><link rel="prefetch" href="/assets/js/12.4c48405a.js"><link rel="prefetch" href="/assets/js/120.765b0524.js"><link rel="prefetch" href="/assets/js/121.f3678383.js"><link rel="prefetch" href="/assets/js/122.dce24747.js"><link rel="prefetch" href="/assets/js/123.b63b10d4.js"><link rel="prefetch" href="/assets/js/124.9bb27c17.js"><link rel="prefetch" href="/assets/js/125.68a30edd.js"><link rel="prefetch" href="/assets/js/126.21af8edc.js"><link rel="prefetch" href="/assets/js/127.a985d0d8.js"><link rel="prefetch" href="/assets/js/128.8163fa1b.js"><link rel="prefetch" href="/assets/js/129.c080aa6d.js"><link rel="prefetch" href="/assets/js/13.ca90848f.js"><link rel="prefetch" href="/assets/js/130.d515f028.js"><link rel="prefetch" href="/assets/js/131.96da42f5.js"><link rel="prefetch" href="/assets/js/132.f9dd7e91.js"><link rel="prefetch" href="/assets/js/133.49645cc4.js"><link rel="prefetch" href="/assets/js/134.d1975511.js"><link rel="prefetch" href="/assets/js/135.6c06e2db.js"><link rel="prefetch" href="/assets/js/136.761d8fa8.js"><link rel="prefetch" href="/assets/js/137.b78b5079.js"><link rel="prefetch" href="/assets/js/138.c7087713.js"><link rel="prefetch" href="/assets/js/139.9eb29936.js"><link rel="prefetch" href="/assets/js/14.66eebc6d.js"><link rel="prefetch" href="/assets/js/140.e227972e.js"><link rel="prefetch" href="/assets/js/141.f4cd2178.js"><link rel="prefetch" href="/assets/js/142.0c7fb726.js"><link rel="prefetch" href="/assets/js/143.9527be83.js"><link rel="prefetch" href="/assets/js/144.1f503a67.js"><link rel="prefetch" href="/assets/js/145.9db35ef4.js"><link rel="prefetch" href="/assets/js/146.89510138.js"><link rel="prefetch" href="/assets/js/147.969b5194.js"><link rel="prefetch" href="/assets/js/148.542d0570.js"><link rel="prefetch" href="/assets/js/149.40c4a556.js"><link rel="prefetch" href="/assets/js/15.43bf9dc7.js"><link rel="prefetch" href="/assets/js/150.47f1d515.js"><link rel="prefetch" href="/assets/js/151.f251c79f.js"><link rel="prefetch" href="/assets/js/152.198d6efb.js"><link rel="prefetch" href="/assets/js/153.5f4e036b.js"><link rel="prefetch" href="/assets/js/154.add790a9.js"><link rel="prefetch" href="/assets/js/155.d4c854aa.js"><link rel="prefetch" href="/assets/js/156.0bf09079.js"><link rel="prefetch" href="/assets/js/157.fe6fbc9c.js"><link rel="prefetch" href="/assets/js/158.b6155892.js"><link rel="prefetch" href="/assets/js/159.969149d7.js"><link rel="prefetch" href="/assets/js/16.d2fb5036.js"><link rel="prefetch" href="/assets/js/160.e29992d4.js"><link rel="prefetch" href="/assets/js/161.1cd134b5.js"><link rel="prefetch" href="/assets/js/162.53924849.js"><link rel="prefetch" href="/assets/js/163.9f7017a0.js"><link rel="prefetch" href="/assets/js/164.62e12d30.js"><link rel="prefetch" href="/assets/js/165.fcaac3f9.js"><link rel="prefetch" href="/assets/js/166.06a8de0d.js"><link rel="prefetch" href="/assets/js/167.09275c11.js"><link rel="prefetch" href="/assets/js/168.e3979906.js"><link rel="prefetch" href="/assets/js/169.8557aa7c.js"><link rel="prefetch" href="/assets/js/17.0dc295c9.js"><link rel="prefetch" href="/assets/js/170.6c329603.js"><link rel="prefetch" href="/assets/js/171.f8914769.js"><link rel="prefetch" href="/assets/js/172.63e446c1.js"><link rel="prefetch" href="/assets/js/173.290ef6a3.js"><link rel="prefetch" href="/assets/js/174.d86897c8.js"><link rel="prefetch" href="/assets/js/175.52d930f3.js"><link rel="prefetch" href="/assets/js/176.483d45ae.js"><link rel="prefetch" href="/assets/js/177.4e40876a.js"><link rel="prefetch" href="/assets/js/178.73f8f77f.js"><link rel="prefetch" href="/assets/js/179.9b132ea4.js"><link rel="prefetch" href="/assets/js/18.40cc5fb0.js"><link rel="prefetch" href="/assets/js/180.88ff7121.js"><link rel="prefetch" href="/assets/js/181.7b6deef5.js"><link rel="prefetch" href="/assets/js/182.b157bcef.js"><link rel="prefetch" href="/assets/js/183.fc45ef1f.js"><link rel="prefetch" href="/assets/js/184.0126b316.js"><link rel="prefetch" href="/assets/js/185.36a5be8f.js"><link rel="prefetch" href="/assets/js/186.5dd1869c.js"><link rel="prefetch" href="/assets/js/187.6ff8df1b.js"><link rel="prefetch" href="/assets/js/188.42ca4824.js"><link rel="prefetch" href="/assets/js/189.a1554dd6.js"><link rel="prefetch" href="/assets/js/19.e46591ce.js"><link rel="prefetch" href="/assets/js/190.da803251.js"><link rel="prefetch" href="/assets/js/191.79abb79d.js"><link rel="prefetch" href="/assets/js/192.61f4df5d.js"><link rel="prefetch" href="/assets/js/193.cddd3be4.js"><link rel="prefetch" href="/assets/js/194.23904d01.js"><link rel="prefetch" href="/assets/js/195.c36d563a.js"><link rel="prefetch" href="/assets/js/196.2ea34f68.js"><link rel="prefetch" href="/assets/js/197.c7972a72.js"><link rel="prefetch" href="/assets/js/198.e6fa95de.js"><link rel="prefetch" href="/assets/js/199.654c8bed.js"><link rel="prefetch" href="/assets/js/20.cf088c3b.js"><link rel="prefetch" href="/assets/js/200.9fbabfd8.js"><link rel="prefetch" href="/assets/js/201.402958d6.js"><link rel="prefetch" href="/assets/js/202.6e175e32.js"><link rel="prefetch" href="/assets/js/203.c86bd61f.js"><link rel="prefetch" href="/assets/js/204.0b204ddf.js"><link rel="prefetch" href="/assets/js/205.ddac5d79.js"><link rel="prefetch" href="/assets/js/206.b30410f3.js"><link rel="prefetch" href="/assets/js/207.b5fc1fb0.js"><link rel="prefetch" href="/assets/js/208.a4c49e12.js"><link rel="prefetch" href="/assets/js/209.795a9e38.js"><link rel="prefetch" href="/assets/js/21.7c4456b0.js"><link rel="prefetch" href="/assets/js/210.30776796.js"><link rel="prefetch" href="/assets/js/211.19d16e44.js"><link rel="prefetch" href="/assets/js/212.364029ca.js"><link rel="prefetch" href="/assets/js/213.2f4abd10.js"><link rel="prefetch" href="/assets/js/214.b6a1982e.js"><link rel="prefetch" href="/assets/js/215.3cb6bd9b.js"><link rel="prefetch" href="/assets/js/216.21ddd4ec.js"><link rel="prefetch" href="/assets/js/217.f4596bba.js"><link rel="prefetch" href="/assets/js/218.14568854.js"><link rel="prefetch" href="/assets/js/219.529907d2.js"><link rel="prefetch" href="/assets/js/22.0d791f94.js"><link rel="prefetch" href="/assets/js/220.3f8a3df4.js"><link rel="prefetch" href="/assets/js/221.9a070120.js"><link rel="prefetch" href="/assets/js/222.3a6efd1b.js"><link rel="prefetch" href="/assets/js/223.53dc5a1d.js"><link rel="prefetch" href="/assets/js/224.74cd1292.js"><link rel="prefetch" href="/assets/js/225.2c88cca0.js"><link rel="prefetch" href="/assets/js/226.67d7cfb6.js"><link rel="prefetch" href="/assets/js/227.b0be672f.js"><link rel="prefetch" href="/assets/js/228.9be8bd64.js"><link rel="prefetch" href="/assets/js/229.d6715c70.js"><link rel="prefetch" href="/assets/js/23.02b0d4f9.js"><link rel="prefetch" href="/assets/js/230.5fc59bdb.js"><link rel="prefetch" href="/assets/js/231.80c7d83c.js"><link rel="prefetch" href="/assets/js/232.5f009b92.js"><link rel="prefetch" href="/assets/js/233.0c3e3d9a.js"><link rel="prefetch" href="/assets/js/234.7448f8c2.js"><link rel="prefetch" href="/assets/js/235.e0326db2.js"><link rel="prefetch" href="/assets/js/236.c314e5cb.js"><link rel="prefetch" href="/assets/js/237.ae436b0b.js"><link rel="prefetch" href="/assets/js/238.a2e09970.js"><link rel="prefetch" href="/assets/js/239.01b0f9e4.js"><link rel="prefetch" href="/assets/js/24.cc9cb1b0.js"><link rel="prefetch" href="/assets/js/240.3dddd9a8.js"><link rel="prefetch" href="/assets/js/241.a407e6b5.js"><link rel="prefetch" href="/assets/js/242.bb22f612.js"><link rel="prefetch" href="/assets/js/243.9e2d1d28.js"><link rel="prefetch" href="/assets/js/244.6388081c.js"><link rel="prefetch" href="/assets/js/245.0a2dc511.js"><link rel="prefetch" href="/assets/js/246.c50fb555.js"><link rel="prefetch" href="/assets/js/247.03779e96.js"><link rel="prefetch" href="/assets/js/248.3e2679e1.js"><link rel="prefetch" href="/assets/js/249.d482b65c.js"><link rel="prefetch" href="/assets/js/25.77e4633a.js"><link rel="prefetch" href="/assets/js/250.252cd1e4.js"><link rel="prefetch" href="/assets/js/251.dfedae2f.js"><link rel="prefetch" href="/assets/js/252.f52fdf79.js"><link rel="prefetch" href="/assets/js/253.0db69c70.js"><link rel="prefetch" href="/assets/js/254.3cbc02f2.js"><link rel="prefetch" href="/assets/js/255.4b037714.js"><link rel="prefetch" href="/assets/js/256.1dd96142.js"><link rel="prefetch" href="/assets/js/257.4ae76c50.js"><link rel="prefetch" href="/assets/js/258.7d0a6f76.js"><link rel="prefetch" href="/assets/js/259.3e59c25b.js"><link rel="prefetch" href="/assets/js/26.0057d37b.js"><link rel="prefetch" href="/assets/js/260.d42456a7.js"><link rel="prefetch" href="/assets/js/261.3a7da063.js"><link rel="prefetch" href="/assets/js/262.29e7a46e.js"><link rel="prefetch" href="/assets/js/263.b9f4e89c.js"><link rel="prefetch" href="/assets/js/264.76ed2bf4.js"><link rel="prefetch" href="/assets/js/265.c0be4a69.js"><link rel="prefetch" href="/assets/js/266.3964ecfd.js"><link rel="prefetch" href="/assets/js/267.e0fbb1dd.js"><link rel="prefetch" href="/assets/js/268.f666665e.js"><link rel="prefetch" href="/assets/js/269.c56d2663.js"><link rel="prefetch" href="/assets/js/27.9e25f953.js"><link rel="prefetch" href="/assets/js/270.7baa3442.js"><link rel="prefetch" href="/assets/js/271.dff1303b.js"><link rel="prefetch" href="/assets/js/272.fdfad01a.js"><link rel="prefetch" href="/assets/js/273.25ed55ad.js"><link rel="prefetch" href="/assets/js/274.7793f462.js"><link rel="prefetch" href="/assets/js/275.31cba1fb.js"><link rel="prefetch" href="/assets/js/276.71f0995d.js"><link rel="prefetch" href="/assets/js/277.f0930c44.js"><link rel="prefetch" href="/assets/js/278.0b80b0ad.js"><link rel="prefetch" href="/assets/js/279.231c462f.js"><link rel="prefetch" href="/assets/js/28.de5fbffd.js"><link rel="prefetch" href="/assets/js/280.78ed8912.js"><link rel="prefetch" href="/assets/js/281.ccc88986.js"><link rel="prefetch" href="/assets/js/282.71f81ecb.js"><link rel="prefetch" href="/assets/js/283.1c8061bb.js"><link rel="prefetch" href="/assets/js/284.1882163b.js"><link rel="prefetch" href="/assets/js/285.2b844926.js"><link rel="prefetch" href="/assets/js/286.c949ae22.js"><link rel="prefetch" href="/assets/js/287.8f1dbd21.js"><link rel="prefetch" href="/assets/js/288.fad9fd97.js"><link rel="prefetch" href="/assets/js/289.31291ff5.js"><link rel="prefetch" href="/assets/js/29.a31435b1.js"><link rel="prefetch" href="/assets/js/290.bb612810.js"><link rel="prefetch" href="/assets/js/291.a5982298.js"><link rel="prefetch" href="/assets/js/292.328081a0.js"><link rel="prefetch" href="/assets/js/293.7c4d5929.js"><link rel="prefetch" href="/assets/js/294.728fa22d.js"><link rel="prefetch" href="/assets/js/295.18bbb892.js"><link rel="prefetch" href="/assets/js/296.0802f31b.js"><link rel="prefetch" href="/assets/js/297.d498b99b.js"><link rel="prefetch" href="/assets/js/298.744f87bc.js"><link rel="prefetch" href="/assets/js/299.356c785f.js"><link rel="prefetch" href="/assets/js/30.60649b66.js"><link rel="prefetch" href="/assets/js/300.1d815de6.js"><link rel="prefetch" href="/assets/js/301.ad2aa425.js"><link rel="prefetch" href="/assets/js/302.91d8ea1d.js"><link rel="prefetch" href="/assets/js/303.7973d48b.js"><link rel="prefetch" href="/assets/js/304.7bc233da.js"><link rel="prefetch" href="/assets/js/305.c6037dae.js"><link rel="prefetch" href="/assets/js/306.c15c56a9.js"><link rel="prefetch" href="/assets/js/307.fe1ddc60.js"><link rel="prefetch" href="/assets/js/308.6a14ee97.js"><link rel="prefetch" href="/assets/js/309.c25c222d.js"><link rel="prefetch" href="/assets/js/31.fab44020.js"><link rel="prefetch" href="/assets/js/310.c9c0dfc0.js"><link rel="prefetch" href="/assets/js/311.d8834753.js"><link rel="prefetch" href="/assets/js/312.dd2cbfbc.js"><link rel="prefetch" href="/assets/js/313.8dc5ff37.js"><link rel="prefetch" href="/assets/js/314.27fee31b.js"><link rel="prefetch" href="/assets/js/315.a9cc87e8.js"><link rel="prefetch" href="/assets/js/316.8b773539.js"><link rel="prefetch" href="/assets/js/317.199246e8.js"><link rel="prefetch" href="/assets/js/318.176dca9f.js"><link rel="prefetch" href="/assets/js/319.638c76ac.js"><link rel="prefetch" href="/assets/js/32.e5e702b0.js"><link rel="prefetch" href="/assets/js/320.8970f678.js"><link rel="prefetch" href="/assets/js/321.33c135ca.js"><link rel="prefetch" href="/assets/js/322.c8f1b963.js"><link rel="prefetch" href="/assets/js/323.aa60992f.js"><link rel="prefetch" href="/assets/js/324.b469c78d.js"><link rel="prefetch" href="/assets/js/325.e0a46e04.js"><link rel="prefetch" href="/assets/js/326.3316fa8a.js"><link rel="prefetch" href="/assets/js/327.68096f5a.js"><link rel="prefetch" href="/assets/js/328.0f65a370.js"><link rel="prefetch" href="/assets/js/329.bc3e4d5e.js"><link rel="prefetch" href="/assets/js/33.b678d537.js"><link rel="prefetch" href="/assets/js/330.d33b58f5.js"><link rel="prefetch" href="/assets/js/331.d4aaa867.js"><link rel="prefetch" href="/assets/js/332.7b718a24.js"><link rel="prefetch" href="/assets/js/333.4c8f3f48.js"><link rel="prefetch" href="/assets/js/334.77f627b0.js"><link rel="prefetch" href="/assets/js/335.6301fcec.js"><link rel="prefetch" href="/assets/js/336.d0619713.js"><link rel="prefetch" href="/assets/js/337.03f5cc53.js"><link rel="prefetch" href="/assets/js/338.d6ff8899.js"><link rel="prefetch" href="/assets/js/339.82208419.js"><link rel="prefetch" href="/assets/js/34.7b065e16.js"><link rel="prefetch" href="/assets/js/340.ce786d32.js"><link rel="prefetch" href="/assets/js/341.624a7781.js"><link rel="prefetch" href="/assets/js/342.433fdcba.js"><link rel="prefetch" href="/assets/js/343.0b6ffb88.js"><link rel="prefetch" href="/assets/js/344.34143c79.js"><link rel="prefetch" href="/assets/js/345.26aa2523.js"><link rel="prefetch" href="/assets/js/347.ef134bbe.js"><link rel="prefetch" href="/assets/js/348.919da774.js"><link rel="prefetch" href="/assets/js/349.fb09fb35.js"><link rel="prefetch" href="/assets/js/35.0a7b7db7.js"><link rel="prefetch" href="/assets/js/350.e21c2679.js"><link rel="prefetch" href="/assets/js/351.4615a918.js"><link rel="prefetch" href="/assets/js/352.7df7cd8d.js"><link rel="prefetch" href="/assets/js/353.8bbc59fc.js"><link rel="prefetch" href="/assets/js/354.83148b34.js"><link rel="prefetch" href="/assets/js/355.86477271.js"><link rel="prefetch" href="/assets/js/356.fe78f1d7.js"><link rel="prefetch" href="/assets/js/357.cf78e7b6.js"><link rel="prefetch" href="/assets/js/358.649fac19.js"><link rel="prefetch" href="/assets/js/359.4ca2f58b.js"><link rel="prefetch" href="/assets/js/36.8a8c44ca.js"><link rel="prefetch" href="/assets/js/360.7787e5b0.js"><link rel="prefetch" href="/assets/js/361.7475396f.js"><link rel="prefetch" href="/assets/js/362.e19135ac.js"><link rel="prefetch" href="/assets/js/363.25e06219.js"><link rel="prefetch" href="/assets/js/364.682b9d36.js"><link rel="prefetch" href="/assets/js/365.6c7b112e.js"><link rel="prefetch" href="/assets/js/366.61261f46.js"><link rel="prefetch" href="/assets/js/367.1c86e56f.js"><link rel="prefetch" href="/assets/js/368.1577ec72.js"><link rel="prefetch" href="/assets/js/369.a5290852.js"><link rel="prefetch" href="/assets/js/37.3719f45f.js"><link rel="prefetch" href="/assets/js/370.62ce1c3a.js"><link rel="prefetch" href="/assets/js/371.100d5619.js"><link rel="prefetch" href="/assets/js/372.564e6555.js"><link rel="prefetch" href="/assets/js/373.8feee139.js"><link rel="prefetch" href="/assets/js/374.9b697c81.js"><link rel="prefetch" href="/assets/js/375.4609e8a8.js"><link rel="prefetch" href="/assets/js/376.44c0f2e4.js"><link rel="prefetch" href="/assets/js/377.dcc5c2d7.js"><link rel="prefetch" href="/assets/js/378.6ecaa06e.js"><link rel="prefetch" href="/assets/js/379.d63e069e.js"><link rel="prefetch" href="/assets/js/38.c6f83038.js"><link rel="prefetch" href="/assets/js/380.244a3e32.js"><link rel="prefetch" href="/assets/js/381.18a6a0d9.js"><link rel="prefetch" href="/assets/js/382.c686640f.js"><link rel="prefetch" href="/assets/js/383.ed1eafd6.js"><link rel="prefetch" href="/assets/js/384.2417107c.js"><link rel="prefetch" href="/assets/js/385.942c6326.js"><link rel="prefetch" href="/assets/js/386.28142e44.js"><link rel="prefetch" href="/assets/js/387.48ef9675.js"><link rel="prefetch" href="/assets/js/388.1e13b77a.js"><link rel="prefetch" href="/assets/js/389.f2f7dca9.js"><link rel="prefetch" href="/assets/js/39.bdef8540.js"><link rel="prefetch" href="/assets/js/390.a21acc4e.js"><link rel="prefetch" href="/assets/js/391.2b1120ee.js"><link rel="prefetch" href="/assets/js/392.9f4becd0.js"><link rel="prefetch" href="/assets/js/393.d3c54135.js"><link rel="prefetch" href="/assets/js/394.b0f4db97.js"><link rel="prefetch" href="/assets/js/395.4e4a8fc5.js"><link rel="prefetch" href="/assets/js/396.3e2284ba.js"><link rel="prefetch" href="/assets/js/397.b70a72f5.js"><link rel="prefetch" href="/assets/js/398.bad472b5.js"><link rel="prefetch" href="/assets/js/399.07e931c9.js"><link rel="prefetch" href="/assets/js/4.2117a506.js"><link rel="prefetch" href="/assets/js/40.83fa7936.js"><link rel="prefetch" href="/assets/js/400.c413cff0.js"><link rel="prefetch" href="/assets/js/401.e414f4bd.js"><link rel="prefetch" href="/assets/js/402.777a2d21.js"><link rel="prefetch" href="/assets/js/403.772cf532.js"><link rel="prefetch" href="/assets/js/404.b650233c.js"><link rel="prefetch" href="/assets/js/405.6f32eaea.js"><link rel="prefetch" href="/assets/js/406.e341a333.js"><link rel="prefetch" href="/assets/js/407.a3a4fdfe.js"><link rel="prefetch" href="/assets/js/408.767d01be.js"><link rel="prefetch" href="/assets/js/409.4823eace.js"><link rel="prefetch" href="/assets/js/41.3693bb5f.js"><link rel="prefetch" href="/assets/js/410.2ab71a51.js"><link rel="prefetch" href="/assets/js/411.0f80da50.js"><link rel="prefetch" href="/assets/js/412.2f67b685.js"><link rel="prefetch" href="/assets/js/413.dd72b96b.js"><link rel="prefetch" href="/assets/js/414.fdb87a02.js"><link rel="prefetch" href="/assets/js/415.0339a851.js"><link rel="prefetch" href="/assets/js/416.a65c12e5.js"><link rel="prefetch" href="/assets/js/417.9281293a.js"><link rel="prefetch" href="/assets/js/418.6a597d0c.js"><link rel="prefetch" href="/assets/js/419.dbca8277.js"><link rel="prefetch" href="/assets/js/42.d7b203f7.js"><link rel="prefetch" href="/assets/js/420.127e2ad4.js"><link rel="prefetch" href="/assets/js/421.2fb29283.js"><link rel="prefetch" href="/assets/js/422.9e07c12f.js"><link rel="prefetch" href="/assets/js/423.2c790be1.js"><link rel="prefetch" href="/assets/js/424.0cea540d.js"><link rel="prefetch" href="/assets/js/425.1d69a7d5.js"><link rel="prefetch" href="/assets/js/426.33f3aa96.js"><link rel="prefetch" href="/assets/js/427.f1cea67a.js"><link rel="prefetch" href="/assets/js/428.7322d5b7.js"><link rel="prefetch" href="/assets/js/429.c5e15f66.js"><link rel="prefetch" href="/assets/js/43.4f457a21.js"><link rel="prefetch" href="/assets/js/430.2e5fe439.js"><link rel="prefetch" href="/assets/js/431.0e15690d.js"><link rel="prefetch" href="/assets/js/432.37961d61.js"><link rel="prefetch" href="/assets/js/433.28cc0424.js"><link rel="prefetch" href="/assets/js/434.c110db22.js"><link rel="prefetch" href="/assets/js/435.375cf9a2.js"><link rel="prefetch" href="/assets/js/436.b83cbc26.js"><link rel="prefetch" href="/assets/js/437.a08e0ee3.js"><link rel="prefetch" href="/assets/js/438.c1232fea.js"><link rel="prefetch" href="/assets/js/439.e05dc5b1.js"><link rel="prefetch" href="/assets/js/44.b334ed25.js"><link rel="prefetch" href="/assets/js/440.b76701f0.js"><link rel="prefetch" href="/assets/js/441.c05271cc.js"><link rel="prefetch" href="/assets/js/442.68187f75.js"><link rel="prefetch" href="/assets/js/443.df737d8d.js"><link rel="prefetch" href="/assets/js/444.8727e9b8.js"><link rel="prefetch" href="/assets/js/445.2d1969f8.js"><link rel="prefetch" href="/assets/js/446.4fa52b0e.js"><link rel="prefetch" href="/assets/js/447.4a092da2.js"><link rel="prefetch" href="/assets/js/448.a0bf7df7.js"><link rel="prefetch" href="/assets/js/449.e84bab3e.js"><link rel="prefetch" href="/assets/js/45.244b7680.js"><link rel="prefetch" href="/assets/js/450.2a8e3eee.js"><link rel="prefetch" href="/assets/js/451.ade23a75.js"><link rel="prefetch" href="/assets/js/452.b35edf93.js"><link rel="prefetch" href="/assets/js/453.edd40e45.js"><link rel="prefetch" href="/assets/js/454.15321733.js"><link rel="prefetch" href="/assets/js/455.12386bc6.js"><link rel="prefetch" href="/assets/js/456.6197f646.js"><link rel="prefetch" href="/assets/js/457.420d2328.js"><link rel="prefetch" href="/assets/js/458.3fa5a793.js"><link rel="prefetch" href="/assets/js/459.225502a5.js"><link rel="prefetch" href="/assets/js/46.508f7d41.js"><link rel="prefetch" href="/assets/js/460.bdf4ddb1.js"><link rel="prefetch" href="/assets/js/461.424cd0f4.js"><link rel="prefetch" href="/assets/js/462.b884d779.js"><link rel="prefetch" href="/assets/js/463.9df633e8.js"><link rel="prefetch" href="/assets/js/464.51220723.js"><link rel="prefetch" href="/assets/js/465.7dada385.js"><link rel="prefetch" href="/assets/js/466.c27be7f5.js"><link rel="prefetch" href="/assets/js/467.100fcce8.js"><link rel="prefetch" href="/assets/js/468.087af9ee.js"><link rel="prefetch" href="/assets/js/469.b0f21610.js"><link rel="prefetch" href="/assets/js/47.a8742825.js"><link rel="prefetch" href="/assets/js/470.0d5c4f98.js"><link rel="prefetch" href="/assets/js/471.76275b82.js"><link rel="prefetch" href="/assets/js/472.3137d241.js"><link rel="prefetch" href="/assets/js/473.5bd078e9.js"><link rel="prefetch" href="/assets/js/474.f6e15a59.js"><link rel="prefetch" href="/assets/js/475.9c18c5ac.js"><link rel="prefetch" href="/assets/js/476.aa2613cf.js"><link rel="prefetch" href="/assets/js/477.f818ee1d.js"><link rel="prefetch" href="/assets/js/478.4af6558a.js"><link rel="prefetch" href="/assets/js/479.ace0d968.js"><link rel="prefetch" href="/assets/js/48.ad2c2a29.js"><link rel="prefetch" href="/assets/js/480.6b4eea31.js"><link rel="prefetch" href="/assets/js/481.c9d0acea.js"><link rel="prefetch" href="/assets/js/482.d88a80ec.js"><link rel="prefetch" href="/assets/js/483.ee3e855c.js"><link rel="prefetch" href="/assets/js/484.869cc523.js"><link rel="prefetch" href="/assets/js/485.beef1484.js"><link rel="prefetch" href="/assets/js/486.bbf2f616.js"><link rel="prefetch" href="/assets/js/487.1238d1f9.js"><link rel="prefetch" href="/assets/js/488.62ce8941.js"><link rel="prefetch" href="/assets/js/489.8d194acf.js"><link rel="prefetch" href="/assets/js/49.a22d6593.js"><link rel="prefetch" href="/assets/js/490.f8f65530.js"><link rel="prefetch" href="/assets/js/491.79e30f28.js"><link rel="prefetch" href="/assets/js/492.f3c77726.js"><link rel="prefetch" href="/assets/js/493.6cc423a5.js"><link rel="prefetch" href="/assets/js/494.0de60756.js"><link rel="prefetch" href="/assets/js/495.6036bf1d.js"><link rel="prefetch" href="/assets/js/496.8f20a53b.js"><link rel="prefetch" href="/assets/js/497.1110680f.js"><link rel="prefetch" href="/assets/js/498.96d410ed.js"><link rel="prefetch" href="/assets/js/499.e19e36d3.js"><link rel="prefetch" href="/assets/js/5.2a4451ec.js"><link rel="prefetch" href="/assets/js/50.7d8944cd.js"><link rel="prefetch" href="/assets/js/500.ba161f2c.js"><link rel="prefetch" href="/assets/js/501.89ef3401.js"><link rel="prefetch" href="/assets/js/502.9ce4c8c2.js"><link rel="prefetch" href="/assets/js/503.e1d73c9d.js"><link rel="prefetch" href="/assets/js/504.dd01c299.js"><link rel="prefetch" href="/assets/js/505.42a4770b.js"><link rel="prefetch" href="/assets/js/506.88720efe.js"><link rel="prefetch" href="/assets/js/507.bd695b5a.js"><link rel="prefetch" href="/assets/js/508.9595643a.js"><link rel="prefetch" href="/assets/js/509.31b3481d.js"><link rel="prefetch" href="/assets/js/51.fd01b1a1.js"><link rel="prefetch" href="/assets/js/510.6cfb92a7.js"><link rel="prefetch" href="/assets/js/511.ee32c143.js"><link rel="prefetch" href="/assets/js/512.2609ef0f.js"><link rel="prefetch" href="/assets/js/513.43bfca22.js"><link rel="prefetch" href="/assets/js/514.6f5db7b5.js"><link rel="prefetch" href="/assets/js/515.5dcce00f.js"><link rel="prefetch" href="/assets/js/516.68d6db54.js"><link rel="prefetch" href="/assets/js/517.378297e9.js"><link rel="prefetch" href="/assets/js/518.1342aa7e.js"><link rel="prefetch" href="/assets/js/519.59d8763a.js"><link rel="prefetch" href="/assets/js/52.b3ba6c43.js"><link rel="prefetch" href="/assets/js/520.51cbcbca.js"><link rel="prefetch" href="/assets/js/521.eff039e9.js"><link rel="prefetch" href="/assets/js/522.1512903e.js"><link rel="prefetch" href="/assets/js/523.1d668421.js"><link rel="prefetch" href="/assets/js/524.8cf6a170.js"><link rel="prefetch" href="/assets/js/525.26e8ea16.js"><link rel="prefetch" href="/assets/js/526.eca245ae.js"><link rel="prefetch" href="/assets/js/527.238756be.js"><link rel="prefetch" href="/assets/js/528.e671f9c6.js"><link rel="prefetch" href="/assets/js/529.69f70492.js"><link rel="prefetch" href="/assets/js/53.fab1833e.js"><link rel="prefetch" href="/assets/js/530.433aafed.js"><link rel="prefetch" href="/assets/js/531.1d2d47b1.js"><link rel="prefetch" href="/assets/js/532.6abf38e1.js"><link rel="prefetch" href="/assets/js/533.1a4cdf18.js"><link rel="prefetch" href="/assets/js/534.2e89f52f.js"><link rel="prefetch" href="/assets/js/535.87d4979f.js"><link rel="prefetch" href="/assets/js/536.5b1428e7.js"><link rel="prefetch" href="/assets/js/537.ec31b495.js"><link rel="prefetch" href="/assets/js/538.4664d0d5.js"><link rel="prefetch" href="/assets/js/539.40e1fb08.js"><link rel="prefetch" href="/assets/js/54.28efaf2b.js"><link rel="prefetch" href="/assets/js/540.baee926a.js"><link rel="prefetch" href="/assets/js/541.ecfbd0b5.js"><link rel="prefetch" href="/assets/js/542.67d187ad.js"><link rel="prefetch" href="/assets/js/543.2c0907bc.js"><link rel="prefetch" href="/assets/js/544.b0e350de.js"><link rel="prefetch" href="/assets/js/545.5baba41c.js"><link rel="prefetch" href="/assets/js/546.d50b8fd7.js"><link rel="prefetch" href="/assets/js/547.6014a1fb.js"><link rel="prefetch" href="/assets/js/548.38eea2e2.js"><link rel="prefetch" href="/assets/js/549.b928b9da.js"><link rel="prefetch" href="/assets/js/55.5aa8e649.js"><link rel="prefetch" href="/assets/js/550.dfbbdeea.js"><link rel="prefetch" href="/assets/js/551.eda06382.js"><link rel="prefetch" href="/assets/js/552.ffd13096.js"><link rel="prefetch" href="/assets/js/553.d6f806f8.js"><link rel="prefetch" href="/assets/js/554.9ef27554.js"><link rel="prefetch" href="/assets/js/555.44d2b9a6.js"><link rel="prefetch" href="/assets/js/556.22780bbd.js"><link rel="prefetch" href="/assets/js/557.d212d006.js"><link rel="prefetch" href="/assets/js/558.9883b6f0.js"><link rel="prefetch" href="/assets/js/559.885d2a33.js"><link rel="prefetch" href="/assets/js/56.4890c257.js"><link rel="prefetch" href="/assets/js/560.aa0f81a5.js"><link rel="prefetch" href="/assets/js/561.462cb31e.js"><link rel="prefetch" href="/assets/js/562.96ac20d9.js"><link rel="prefetch" href="/assets/js/563.cb607aac.js"><link rel="prefetch" href="/assets/js/564.7761c8e7.js"><link rel="prefetch" href="/assets/js/565.3f5cf8db.js"><link rel="prefetch" href="/assets/js/566.fa44ecbb.js"><link rel="prefetch" href="/assets/js/567.dc696fa5.js"><link rel="prefetch" href="/assets/js/568.6d07529d.js"><link rel="prefetch" href="/assets/js/569.923544e0.js"><link rel="prefetch" href="/assets/js/57.ae3f6a3f.js"><link rel="prefetch" href="/assets/js/570.78abe626.js"><link rel="prefetch" href="/assets/js/571.6515760d.js"><link rel="prefetch" href="/assets/js/572.85f5300f.js"><link rel="prefetch" href="/assets/js/573.f479826f.js"><link rel="prefetch" href="/assets/js/574.fb6e1dba.js"><link rel="prefetch" href="/assets/js/575.3011956c.js"><link rel="prefetch" href="/assets/js/576.d4fa10d4.js"><link rel="prefetch" href="/assets/js/577.d111da6a.js"><link rel="prefetch" href="/assets/js/578.d6260a31.js"><link rel="prefetch" href="/assets/js/579.754e69d4.js"><link rel="prefetch" href="/assets/js/58.c6f9dfb3.js"><link rel="prefetch" href="/assets/js/580.4ed7f822.js"><link rel="prefetch" href="/assets/js/581.48b43019.js"><link rel="prefetch" href="/assets/js/582.a8b4dbd4.js"><link rel="prefetch" href="/assets/js/583.e418b677.js"><link rel="prefetch" href="/assets/js/584.8486038e.js"><link rel="prefetch" href="/assets/js/585.eaf36dd8.js"><link rel="prefetch" href="/assets/js/586.21231467.js"><link rel="prefetch" href="/assets/js/587.2ce0dd7e.js"><link rel="prefetch" href="/assets/js/588.05124709.js"><link rel="prefetch" href="/assets/js/589.3801f779.js"><link rel="prefetch" href="/assets/js/59.9add799d.js"><link rel="prefetch" href="/assets/js/590.a3cbd42b.js"><link rel="prefetch" href="/assets/js/591.dd8628ea.js"><link rel="prefetch" href="/assets/js/592.f8cbec72.js"><link rel="prefetch" href="/assets/js/593.ee2992d3.js"><link rel="prefetch" href="/assets/js/594.992c95fa.js"><link rel="prefetch" href="/assets/js/595.7b06e914.js"><link rel="prefetch" href="/assets/js/596.ecdf9d55.js"><link rel="prefetch" href="/assets/js/597.3ee6ef82.js"><link rel="prefetch" href="/assets/js/598.23e1198a.js"><link rel="prefetch" href="/assets/js/599.283846ca.js"><link rel="prefetch" href="/assets/js/6.3450075a.js"><link rel="prefetch" href="/assets/js/60.cf12c4cd.js"><link rel="prefetch" href="/assets/js/600.d35677d2.js"><link rel="prefetch" href="/assets/js/601.774b015f.js"><link rel="prefetch" href="/assets/js/602.56325d8b.js"><link rel="prefetch" href="/assets/js/603.46f99462.js"><link rel="prefetch" href="/assets/js/604.c3612d5b.js"><link rel="prefetch" href="/assets/js/605.3c1ad5cf.js"><link rel="prefetch" href="/assets/js/606.bdce8358.js"><link rel="prefetch" href="/assets/js/607.b55b581a.js"><link rel="prefetch" href="/assets/js/608.8e1d7684.js"><link rel="prefetch" href="/assets/js/609.9d75d903.js"><link rel="prefetch" href="/assets/js/61.a2162f6b.js"><link rel="prefetch" href="/assets/js/610.d8e37d3f.js"><link rel="prefetch" href="/assets/js/611.8f629cef.js"><link rel="prefetch" href="/assets/js/612.ee9c9adc.js"><link rel="prefetch" href="/assets/js/613.e4cc5b56.js"><link rel="prefetch" href="/assets/js/614.0c67b1ac.js"><link rel="prefetch" href="/assets/js/615.31cc76f7.js"><link rel="prefetch" href="/assets/js/616.414c5a2d.js"><link rel="prefetch" href="/assets/js/617.3b95c869.js"><link rel="prefetch" href="/assets/js/618.b04bde43.js"><link rel="prefetch" href="/assets/js/619.6f51cd68.js"><link rel="prefetch" href="/assets/js/62.63ffdccd.js"><link rel="prefetch" href="/assets/js/620.06e35aab.js"><link rel="prefetch" href="/assets/js/621.9160409d.js"><link rel="prefetch" href="/assets/js/622.f939093a.js"><link rel="prefetch" href="/assets/js/623.46cbdf6c.js"><link rel="prefetch" href="/assets/js/624.f50e872b.js"><link rel="prefetch" href="/assets/js/625.daea081c.js"><link rel="prefetch" href="/assets/js/626.422dda2a.js"><link rel="prefetch" href="/assets/js/627.2912d313.js"><link rel="prefetch" href="/assets/js/628.ca5dd07a.js"><link rel="prefetch" href="/assets/js/629.014a86e0.js"><link rel="prefetch" href="/assets/js/63.ff75527d.js"><link rel="prefetch" href="/assets/js/630.14b36eb7.js"><link rel="prefetch" href="/assets/js/631.1ad06dc6.js"><link rel="prefetch" href="/assets/js/632.871daae8.js"><link rel="prefetch" href="/assets/js/633.7374f323.js"><link rel="prefetch" href="/assets/js/64.d81435ff.js"><link rel="prefetch" href="/assets/js/65.59e05d0e.js"><link rel="prefetch" href="/assets/js/66.053fd06b.js"><link rel="prefetch" href="/assets/js/67.96bf3b2b.js"><link rel="prefetch" href="/assets/js/68.30f75aec.js"><link rel="prefetch" href="/assets/js/69.31b80008.js"><link rel="prefetch" href="/assets/js/7.c5c54fb4.js"><link rel="prefetch" href="/assets/js/70.a4cfbe7e.js"><link rel="prefetch" href="/assets/js/71.c38f1727.js"><link rel="prefetch" href="/assets/js/72.cbfce132.js"><link rel="prefetch" href="/assets/js/73.42d4e18f.js"><link rel="prefetch" href="/assets/js/74.898caca2.js"><link rel="prefetch" href="/assets/js/75.cdb08320.js"><link rel="prefetch" href="/assets/js/76.c9b253ae.js"><link rel="prefetch" href="/assets/js/77.69cebc3b.js"><link rel="prefetch" href="/assets/js/78.0bf148ee.js"><link rel="prefetch" href="/assets/js/79.6b6fe01c.js"><link rel="prefetch" href="/assets/js/8.536033df.js"><link rel="prefetch" href="/assets/js/80.a0142be6.js"><link rel="prefetch" href="/assets/js/81.9c5bfa8e.js"><link rel="prefetch" href="/assets/js/82.be40d68a.js"><link rel="prefetch" href="/assets/js/83.59f67187.js"><link rel="prefetch" href="/assets/js/84.392513b9.js"><link rel="prefetch" href="/assets/js/85.7cba7e9e.js"><link rel="prefetch" href="/assets/js/86.cf02780b.js"><link rel="prefetch" href="/assets/js/87.9bf9f566.js"><link rel="prefetch" href="/assets/js/88.917254e5.js"><link rel="prefetch" href="/assets/js/89.f55ad9a0.js"><link rel="prefetch" href="/assets/js/9.235c01e3.js"><link rel="prefetch" href="/assets/js/90.a09e7153.js"><link rel="prefetch" href="/assets/js/91.daf4923b.js"><link rel="prefetch" href="/assets/js/92.2d30ab2b.js"><link rel="prefetch" href="/assets/js/93.03bd52c1.js"><link rel="prefetch" href="/assets/js/94.f6913770.js"><link rel="prefetch" href="/assets/js/95.1d2f787b.js"><link rel="prefetch" href="/assets/js/96.6317b766.js"><link rel="prefetch" href="/assets/js/97.ee491ea1.js"><link rel="prefetch" href="/assets/js/98.f6e8f03e.js"><link rel="prefetch" href="/assets/js/99.b3278d07.js"><link rel="prefetch" href="/assets/js/vendors~docsearch.eff714eb.js">
    <link rel="stylesheet" href="/assets/css/0.styles.ccadf850.css">
  </head>
  <body>
    <div id="app" data-server-rendered="true"><div class="theme-container"><header class="navbar"><div class="sidebar-button"><svg xmlns="http://www.w3.org/2000/svg" aria-hidden="true" role="img" viewBox="0 0 448 512" class="icon"><path fill="currentColor" d="M436 124H12c-6.627 0-12-5.373-12-12V80c0-6.627 5.373-12 12-12h424c6.627 0 12 5.373 12 12v32c0 6.627-5.373 12-12 12zm0 160H12c-6.627 0-12-5.373-12-12v-32c0-6.627 5.373-12 12-12h424c6.627 0 12 5.373 12 12v32c0 6.627-5.373 12-12 12zm0 160H12c-6.627 0-12-5.373-12-12v-32c0-6.627 5.373-12 12-12h424c6.627 0 12 5.373 12 12v32c0 6.627-5.373 12-12 12z"></path></svg></div> <a href="/zh/" class="home-link router-link-active"><img src="/img/logo.png" alt=" " class="logo"></a> <div class="links"><div class="search-box"><input aria-label="Search" autocomplete="off" spellcheck="false" value=""> <!----></div> <nav class="nav-links can-hide"><div class="nav-item"><div class="dropdown-wrapper"><a class="dropdown-title"><span class="title">文档</span> <span class="arrow right"></span></a> <ul class="nav-dropdown" style="display:none;"><li class="dropdown-item"><!----> <a href="/zh/UserGuide/Master/QuickStart/QuickStart.html" class="nav-link">In progress</a></li><li class="dropdown-item"><!----> <a href="/zh/UserGuide/V0.12.x/QuickStart/QuickStart.html" class="nav-link">V0.12.x</a></li><li class="dropdown-item"><!----> <a href="/zh/UserGuide/V0.11.x/Get Started/QuickStart.html" class="nav-link">V0.11.x</a></li><li class="dropdown-item"><!----> <a href="/zh/UserGuide/V0.10.x/Get Started/QuickStart.html" class="nav-link">V0.10.x</a></li><li class="dropdown-item"><!----> <a href="/zh/UserGuide/V0.9.x/0-Get Started/1-QuickStart.html" class="nav-link">V0.9.x</a></li><li class="dropdown-item"><!----> <a href="/zh/UserGuide/V0.8.x/0-Get Started/1-QuickStart.html" class="nav-link">V0.8.x</a></li></ul></div></div><div class="nav-item"><a href="/zh/SystemDesign/Architecture/Architecture.html" class="nav-link">系统设计</a></div><div class="nav-item"><a href="/zh/Download/" class="nav-link">下载</a></div><div class="nav-item"><div class="dropdown-wrapper"><a class="dropdown-title"><span class="title">社区</span> <span class="arrow right"></span></a> <ul class="nav-dropdown" style="display:none;"><li class="dropdown-item"><!----> <a href="https://cwiki.apache.org/confluence/display/iotdb" class="nav-link external">
  Wiki
  <!----></a></li><li class="dropdown-item"><!----> <a href="/zh/Community/Community-Project Committers.html" class="nav-link">开发人员</a></li><li class="dropdown-item"><!----> <a href="/zh/Community/Community-Powered By.html" class="nav-link">技术支持</a></li><li class="dropdown-item"><!----> <a href="/Community/Materials.html" class="nav-link">活动与报告</a></li><li class="dropdown-item"><!----> <a href="/zh/Community/Feedback.html" class="nav-link">交流与反馈</a></li></ul></div></div><div class="nav-item"><div class="dropdown-wrapper"><a class="dropdown-title"><span class="title">开发</span> <span class="arrow right"></span></a> <ul class="nav-dropdown" style="display:none;"><li class="dropdown-item"><!----> <a href="/zh/Development/VoteRelease.html" class="nav-link">如何投票</a></li><li class="dropdown-item"><!----> <a href="/zh/Development/HowToCommit.html" class="nav-link">如何提交代码</a></li><li class="dropdown-item"><!----> <a href="/zh/Development/Committer.html" class="nav-link">成为Committer</a></li><li class="dropdown-item"><!----> <a href="/zh/Development/ContributeGuide.html" class="nav-link">项目开发指南</a></li><li class="dropdown-item"><!----> <a href="/zh/Development/format-changelist.html" class="nav-link">TsFile的更改列表</a></li><li class="dropdown-item"><!----> <a href="/zh/Development/rpc-changelist.html" class="nav-link">RPC变更清单</a></li></ul></div></div><div class="nav-item"><div class="dropdown-wrapper"><a class="dropdown-title"><span class="title">ASF</span> <span class="arrow right"></span></a> <ul class="nav-dropdown" style="display:none;"><li class="dropdown-item"><!----> <a href="http://www.apache.org/" class="nav-link external">
  基金会
  <!----></a></li><li class="dropdown-item"><!----> <a href="http://www.apache.org/licenses/" class="nav-link external">
  许可证
  <!----></a></li><li class="dropdown-item"><!----> <a href="http://www.apache.org/security/" class="nav-link external">
  安全
  <!----></a></li><li class="dropdown-item"><!----> <a href="http://www.apache.org/foundation/sponsorship.html" class="nav-link external">
  赞助
  <!----></a></li><li class="dropdown-item"><!----> <a href="http://www.apache.org/foundation/thanks.html" class="nav-link external">
  致谢
  <!----></a></li><li class="dropdown-item"><!----> <a href="http://www.apache.org/events/current-event" class="nav-link external">
  活动
  <!----></a></li></ul></div></div><div class="nav-item"><div class="dropdown-wrapper"><a class="dropdown-title"><span class="title">语言</span> <span class="arrow right"></span></a> <ul class="nav-dropdown" style="display:none;"><li class="dropdown-item"><!----> <a href="/SystemDesign/DataQuery/LastQuery.html" class="nav-link">English</a></li><li class="dropdown-item"><!----> <a href="/zh/SystemDesign/DataQuery/LastQuery.html" aria-current="page" class="nav-link router-link-exact-active router-link-active">简体中文</a></li></ul></div></div> <a href="https://github.com/apache/iotdb.git" target="_blank" rel="noopener noreferrer" class="repo-link">
    gitHub
    <span><svg xmlns="http://www.w3.org/2000/svg" aria-hidden="true" focusable="false" x="0px" y="0px" viewBox="0 0 100 100" width="15" height="15" class="icon outbound"><path fill="currentColor" d="M18.8,85.1h56l0,0c2.2,0,4-1.8,4-4v-32h-8v28h-48v-48h28v-8h-32l0,0c-2.2,0-4,1.8-4,4v56C14.8,83.3,16.6,85.1,18.8,85.1z"></path> <polygon fill="currentColor" points="45.7,48.7 51.3,54.3 77.2,28.5 77.2,37.2 85.2,37.2 85.2,14.9 62.8,14.9 62.8,22.9 71.5,22.9"></polygon></svg> <span class="sr-only">(opens new window)</span></span></a></nav></div></header> <div class="sidebar-mask"></div> <aside class="sidebar"><nav class="nav-links"><div class="nav-item"><div class="dropdown-wrapper"><a class="dropdown-title"><span class="title">文档</span> <span class="arrow right"></span></a> <ul class="nav-dropdown" style="display:none;"><li class="dropdown-item"><!----> <a href="/zh/UserGuide/Master/QuickStart/QuickStart.html" class="nav-link">In progress</a></li><li class="dropdown-item"><!----> <a href="/zh/UserGuide/V0.12.x/QuickStart/QuickStart.html" class="nav-link">V0.12.x</a></li><li class="dropdown-item"><!----> <a href="/zh/UserGuide/V0.11.x/Get Started/QuickStart.html" class="nav-link">V0.11.x</a></li><li class="dropdown-item"><!----> <a href="/zh/UserGuide/V0.10.x/Get Started/QuickStart.html" class="nav-link">V0.10.x</a></li><li class="dropdown-item"><!----> <a href="/zh/UserGuide/V0.9.x/0-Get Started/1-QuickStart.html" class="nav-link">V0.9.x</a></li><li class="dropdown-item"><!----> <a href="/zh/UserGuide/V0.8.x/0-Get Started/1-QuickStart.html" class="nav-link">V0.8.x</a></li></ul></div></div><div class="nav-item"><a href="/zh/SystemDesign/Architecture/Architecture.html" class="nav-link">系统设计</a></div><div class="nav-item"><a href="/zh/Download/" class="nav-link">下载</a></div><div class="nav-item"><div class="dropdown-wrapper"><a class="dropdown-title"><span class="title">社区</span> <span class="arrow right"></span></a> <ul class="nav-dropdown" style="display:none;"><li class="dropdown-item"><!----> <a href="https://cwiki.apache.org/confluence/display/iotdb" class="nav-link external">
  Wiki
  <!----></a></li><li class="dropdown-item"><!----> <a href="/zh/Community/Community-Project Committers.html" class="nav-link">开发人员</a></li><li class="dropdown-item"><!----> <a href="/zh/Community/Community-Powered By.html" class="nav-link">技术支持</a></li><li class="dropdown-item"><!----> <a href="/Community/Materials.html" class="nav-link">活动与报告</a></li><li class="dropdown-item"><!----> <a href="/zh/Community/Feedback.html" class="nav-link">交流与反馈</a></li></ul></div></div><div class="nav-item"><div class="dropdown-wrapper"><a class="dropdown-title"><span class="title">开发</span> <span class="arrow right"></span></a> <ul class="nav-dropdown" style="display:none;"><li class="dropdown-item"><!----> <a href="/zh/Development/VoteRelease.html" class="nav-link">如何投票</a></li><li class="dropdown-item"><!----> <a href="/zh/Development/HowToCommit.html" class="nav-link">如何提交代码</a></li><li class="dropdown-item"><!----> <a href="/zh/Development/Committer.html" class="nav-link">成为Committer</a></li><li class="dropdown-item"><!----> <a href="/zh/Development/ContributeGuide.html" class="nav-link">项目开发指南</a></li><li class="dropdown-item"><!----> <a href="/zh/Development/format-changelist.html" class="nav-link">TsFile的更改列表</a></li><li class="dropdown-item"><!----> <a href="/zh/Development/rpc-changelist.html" class="nav-link">RPC变更清单</a></li></ul></div></div><div class="nav-item"><div class="dropdown-wrapper"><a class="dropdown-title"><span class="title">ASF</span> <span class="arrow right"></span></a> <ul class="nav-dropdown" style="display:none;"><li class="dropdown-item"><!----> <a href="http://www.apache.org/" class="nav-link external">
  基金会
  <!----></a></li><li class="dropdown-item"><!----> <a href="http://www.apache.org/licenses/" class="nav-link external">
  许可证
  <!----></a></li><li class="dropdown-item"><!----> <a href="http://www.apache.org/security/" class="nav-link external">
  安全
  <!----></a></li><li class="dropdown-item"><!----> <a href="http://www.apache.org/foundation/sponsorship.html" class="nav-link external">
  赞助
  <!----></a></li><li class="dropdown-item"><!----> <a href="http://www.apache.org/foundation/thanks.html" class="nav-link external">
  致谢
  <!----></a></li><li class="dropdown-item"><!----> <a href="http://www.apache.org/events/current-event" class="nav-link external">
  活动
  <!----></a></li></ul></div></div><div class="nav-item"><div class="dropdown-wrapper"><a class="dropdown-title"><span class="title">语言</span> <span class="arrow right"></span></a> <ul class="nav-dropdown" style="display:none;"><li class="dropdown-item"><!----> <a href="/SystemDesign/DataQuery/LastQuery.html" class="nav-link">English</a></li><li class="dropdown-item"><!----> <a href="/zh/SystemDesign/DataQuery/LastQuery.html" aria-current="page" class="nav-link router-link-exact-active router-link-active">简体中文</a></li></ul></div></div> <a href="https://github.com/apache/iotdb.git" target="_blank" rel="noopener noreferrer" class="repo-link">
    gitHub
    <span><svg xmlns="http://www.w3.org/2000/svg" aria-hidden="true" focusable="false" x="0px" y="0px" viewBox="0 0 100 100" width="15" height="15" class="icon outbound"><path fill="currentColor" d="M18.8,85.1h56l0,0c2.2,0,4-1.8,4-4v-32h-8v28h-48v-48h28v-8h-32l0,0c-2.2,0-4,1.8-4,4v56C14.8,83.3,16.6,85.1,18.8,85.1z"></path> <polygon fill="currentColor" points="45.7,48.7 51.3,54.3 77.2,28.5 77.2,37.2 85.2,37.2 85.2,14.9 62.8,14.9 62.8,22.9 71.5,22.9"></polygon></svg> <span class="sr-only">(opens new window)</span></span></a></nav>  <ul class="sidebar-links"><li><section class="sidebar-group depth-0"><p class="sidebar-heading"><span>系统设计</span> <!----></p> <!----></section></li><li><section class="sidebar-group collapsable depth-0"><p class="sidebar-heading"><span>应用概览</span> <span class="arrow right"></span></p> <!----></section></li><li><section class="sidebar-group collapsable depth-0"><p class="sidebar-heading"><span>TsFile</span> <span class="arrow right"></span></p> <!----></section></li><li><section class="sidebar-group collapsable depth-0"><p class="sidebar-heading"><span>查询引擎</span> <span class="arrow right"></span></p> <!----></section></li><li><section class="sidebar-group collapsable depth-0"><p class="sidebar-heading"><span>元数据管理</span> <span class="arrow right"></span></p> <!----></section></li><li><section class="sidebar-group collapsable depth-0"><p class="sidebar-heading"><span>存储引擎</span> <span class="arrow right"></span></p> <!----></section></li><li><section class="sidebar-group collapsable depth-0"><p class="sidebar-heading open"><span>数据查询</span> <span class="arrow down"></span></p> <ul class="sidebar-links sidebar-group-items"><li><a href="/zh/SystemDesign/DataQuery/DataQuery.html" class="sidebar-link">数据查询</a></li><li><a href="/zh/SystemDesign/DataQuery/QueryFundamentals.html" class="sidebar-link">查询基础介绍</a></li><li><a href="/zh/SystemDesign/DataQuery/SeriesReader.html" class="sidebar-link">查询基础组件</a></li><li><a href="/zh/SystemDesign/DataQuery/RawDataQuery.html" class="sidebar-link">原始数据查询</a></li><li><a href="/zh/SystemDesign/DataQuery/AggregationQuery.html" class="sidebar-link">聚合查询</a></li><li><a href="/zh/SystemDesign/DataQuery/GroupByQuery.html" class="sidebar-link">降采样查询</a></li><li><a href="/zh/SystemDesign/DataQuery/LastQuery.html" aria-current="page" class="active sidebar-link">最近时间戳 Last 查询</a></li><li><a href="/zh/SystemDesign/DataQuery/AlignByDeviceQuery.html" class="sidebar-link">按设备对齐查询</a></li><li><a href="/zh/SystemDesign/DataQuery/FillFunction.html" class="sidebar-link">空值填充</a></li><li><a href="/zh/SystemDesign/DataQuery/GroupByFillQuery.html" class="sidebar-link">降采样补空值查询</a></li><li><a href="/zh/SystemDesign/DataQuery/OrderByTimeQuery.html" class="sidebar-link">按时间倒序查询</a></li></ul></section></li><li><section class="sidebar-group collapsable depth-0"><p class="sidebar-heading"><span>工具</span> <span class="arrow right"></span></p> <!----></section></li><li><section class="sidebar-group collapsable depth-0"><p class="sidebar-heading"><span>连接器</span> <span class="arrow right"></span></p> <!----></section></li><li><section class="sidebar-group collapsable depth-0"><p class="sidebar-heading"><span>客户端</span> <span class="arrow right"></span></p> <!----></section></li></ul> </aside> <main class="page"> <div class="content content__default"><h1 id="最近时间戳-last-查询"><a href="#最近时间戳-last-查询" class="header-anchor">#</a> 最近时间戳 Last 查询</h1> <p>Last 查询的主要逻辑在 LastQueryExecutor</p> <ul><li>org.apache.iotdb.db.query.executor.LastQueryExecutor</li></ul> <p>Last查询对每个指定的时间序列执行<code>calculateLastPairForOneSeries</code>方法。</p> <h2 id="读取mnode缓存数据"><a href="#读取mnode缓存数据" class="header-anchor">#</a> 读取MNode缓存数据</h2> <p>我们在需要查询的时间序列所对应的MNode结构中添加Last数据缓存。<code>calculateLastPairForOneSeries</code>方法对于某个时间序列的Last查询，首先尝试读取MNode中的缓存数据。</p> <div class="language- line-numbers-mode"><pre class="language-text"><code>try {
  node = IoTDB.metaManager.getDeviceNodeWithAutoCreateStorageGroup(seriesPath.toString());
} catch (MetadataException e) {
  throw new QueryProcessException(e);
}
if (((LeafMNode) node).getCachedLast() != null) {
  return ((LeafMNode) node).getCachedLast();
}
</code></pre> <div class="line-numbers-wrapper"><span class="line-number">1</span><br><span class="line-number">2</span><br><span class="line-number">3</span><br><span class="line-number">4</span><br><span class="line-number">5</span><br><span class="line-number">6</span><br><span class="line-number">7</span><br><span class="line-number">8</span><br></div></div><p>如果发现缓存没有被写入过，则执行下面的标准查询流程读取TsFile数据。</p> <h2 id="last标准查询流程"><a href="#last标准查询流程" class="header-anchor">#</a> Last标准查询流程</h2> <p>Last标准查询流程需要以倒序方式扫描顺序文件和乱序文件，一旦得到满足要求的Last查询结果就将其写回到MNode缓存中并返回。算法中对顺序文件和乱序文件分别进行处理。</p> <ul><li><p>顺序文件由于是按照写入时间已经排好序，因此直接使用<code>loadTimeSeriesMetadata()</code>方法取出最后一个不为空的<code>TimeseriesMetadata</code>。若<code>TimeseriesMetadata</code>的统计数据可用即可直接得到Last时间戳和对应的值；如不可用则需要使用<code>loadChunkMetadataList()</code>方法得到下一层的最后一个<code>ChunkMetadata</code>，通过统计数据得到Last结果。</p> <div class="language- line-numbers-mode"><pre class="language-text"><code>for (int i = seqFileResources.size() - 1; i &gt;= 0; i--) {
    TimeseriesMetadata timeseriesMetadata = FileLoaderUtils.loadTimeSeriesMetadata(
            seqFileResources.get(i), seriesPath, context, null, sensors);
    if (timeseriesMetadata != null) {
      if (!timeseriesMetadata.isModified()) {
        Statistics timeseriesMetadataStats = timeseriesMetadata.getStatistics();
        resultPair = constructLastPair(
                timeseriesMetadataStats.getEndTime(),
                timeseriesMetadataStats.getLastValue(),
                tsDataType);
        break;
      } else {
        List&lt;ChunkMetadata&gt; chunkMetadataList = timeseriesMetadata.loadChunkMetadataList();
        if (!chunkMetadataList.isEmpty()) {
          ChunkMetadata lastChunkMetaData = chunkMetadataList.get(chunkMetadataList.size() - 1);
          Statistics chunkStatistics = lastChunkMetaData.getStatistics();
          resultPair =
              constructLastPair(
                  chunkStatistics.getEndTime(), chunkStatistics.getLastValue(), tsDataType);
          break;
        }
      }
    }
  }
</code></pre> <div class="line-numbers-wrapper"><span class="line-number">1</span><br><span class="line-number">2</span><br><span class="line-number">3</span><br><span class="line-number">4</span><br><span class="line-number">5</span><br><span class="line-number">6</span><br><span class="line-number">7</span><br><span class="line-number">8</span><br><span class="line-number">9</span><br><span class="line-number">10</span><br><span class="line-number">11</span><br><span class="line-number">12</span><br><span class="line-number">13</span><br><span class="line-number">14</span><br><span class="line-number">15</span><br><span class="line-number">16</span><br><span class="line-number">17</span><br><span class="line-number">18</span><br><span class="line-number">19</span><br><span class="line-number">20</span><br><span class="line-number">21</span><br><span class="line-number">22</span><br><span class="line-number">23</span><br><span class="line-number">24</span><br></div></div></li> <li><p>对于乱序文件，需要遍历所有不为空的<code>TimeseriesMetadata</code>结构并更新当前最大时间戳的Last数据，直到扫描完所有乱序文件为止。需要注意的是当多个<code>ChunkMetadata</code>拥有相同的最大时间戳时，我们取<code>version</code>值最大的<code>ChunkMatadata</code>中的数据作为Last的结果。</p> <div class="language- line-numbers-mode"><pre class="language-text"><code>long version = 0;
for (TsFileResource resource : unseqFileResources) {
  if (resource.getEndTime(seriesPath.getDevice()) &lt; resultPair.getTimestamp()) {
    continue;
  }
  TimeseriesMetadata timeseriesMetadata =
      FileLoaderUtils.loadTimeSeriesMetadata(resource, seriesPath, context, null, sensors);
  if (timeseriesMetadata != null) {
    for (ChunkMetadata chunkMetaData : timeseriesMetadata.loadChunkMetadataList()) {
      if (chunkMetaData.getEndTime() == resultPair.getTimestamp()
          &amp;&amp; chunkMetaData.getVersion() &gt; version) {
        Statistics chunkStatistics = chunkMetaData.getStatistics();
        resultPair =
            constructLastPair(
                chunkStatistics.getEndTime(), chunkStatistics.getLastValue(), tsDataType);
        version = chunkMetaData.getVersion();
      }
    }
  }
}
</code></pre> <div class="line-numbers-wrapper"><span class="line-number">1</span><br><span class="line-number">2</span><br><span class="line-number">3</span><br><span class="line-number">4</span><br><span class="line-number">5</span><br><span class="line-number">6</span><br><span class="line-number">7</span><br><span class="line-number">8</span><br><span class="line-number">9</span><br><span class="line-number">10</span><br><span class="line-number">11</span><br><span class="line-number">12</span><br><span class="line-number">13</span><br><span class="line-number">14</span><br><span class="line-number">15</span><br><span class="line-number">16</span><br><span class="line-number">17</span><br><span class="line-number">18</span><br><span class="line-number">19</span><br><span class="line-number">20</span><br></div></div></li> <li><p>最后将查询结果写入到MNode的Last缓存</p> <div class="language- line-numbers-mode"><pre class="language-text"><code>((LeafMNode) node).updateCachedLast(resultPair, false, Long.MIN_VALUE);
</code></pre> <div class="line-numbers-wrapper"><span class="line-number">1</span><br></div></div></li></ul> <h2 id="last-缓存更新策略"><a href="#last-缓存更新策略" class="header-anchor">#</a> Last 缓存更新策略</h2> <p>Last缓存更新的逻辑位于<code>LeafMNode</code>的<code>updateCachedLast</code>方法内，这里引入两个额外的参数<code>highPriorityUpdate</code>和<code>latestFlushTime</code>。<code>highPriorityUpdate</code>用来表示本次更新是否是高优先级的，新数据写入而导致的缓存更新都被认为是高优先级更新，而查询时更新缓存默认为低优先级更新。<code>latestFlushTime</code>用来记录当前已被写回到磁盘的数据的最大时间戳。</p> <p>缓存更新的策略如下：</p> <ol><li>当缓存中没有记录时，对于查询到的Last数据，将查询的结果直接写入到缓存中。</li> <li>当缓存中没有记录时，对于写入的最新数据如果时间戳大于或等于<code>latestFlushTime</code>，则将写入的数据写入到缓存中。</li> <li>当缓存中已有记录时，根据查询或写入的数据时间戳与当前缓存中时间戳作对比。写入的数据具有高优先级，时间戳不小于缓存记录则更新缓存；查询出的数据低优先级，必须大于缓存记录的时间戳才更新缓存。</li></ol> <p>具体代码如下</p> <div class="language- line-numbers-mode"><pre class="language-text"><code>public synchronized void updateCachedLast(
  TimeValuePair timeValuePair, boolean highPriorityUpdate, Long latestFlushedTime) {
    if (timeValuePair == null || timeValuePair.getValue() == null) return;
    
    if (cachedLastValuePair == null) {
      // If no cached last, (1) a last query (2) an unseq insertion or (3) a seq insertion will update cache.
      if (!highPriorityUpdate || latestFlushedTime &lt;= timeValuePair.getTimestamp()) {
        cachedLastValuePair =
            new TimeValuePair(timeValuePair.getTimestamp(), timeValuePair.getValue());
      }
    } else if (timeValuePair.getTimestamp() &gt; cachedLastValuePair.getTimestamp()
        || (timeValuePair.getTimestamp() == cachedLastValuePair.getTimestamp()
            &amp;&amp; highPriorityUpdate)) {
      cachedLastValuePair.setTimestamp(timeValuePair.getTimestamp());
      cachedLastValuePair.setValue(timeValuePair.getValue());
    }
}
</code></pre> <div class="line-numbers-wrapper"><span class="line-number">1</span><br><span class="line-number">2</span><br><span class="line-number">3</span><br><span class="line-number">4</span><br><span class="line-number">5</span><br><span class="line-number">6</span><br><span class="line-number">7</span><br><span class="line-number">8</span><br><span class="line-number">9</span><br><span class="line-number">10</span><br><span class="line-number">11</span><br><span class="line-number">12</span><br><span class="line-number">13</span><br><span class="line-number">14</span><br><span class="line-number">15</span><br><span class="line-number">16</span><br><span class="line-number">17</span><br></div></div></div> <div class="page-nav"><p class="inner"><span class="prev">
        ←
        <a href="/zh/SystemDesign/DataQuery/GroupByQuery.html" class="prev">
          降采样查询
        </a></span> <span class="next"><a href="/zh/SystemDesign/DataQuery/AlignByDeviceQuery.html">
          按设备对齐查询
        </a>
        →
      </span></p></div> <p style="text-align: center;">Copyright © 2021 The Apache Software Foundation.<br>
     Apache and the Apache feather logo are trademarks of The Apache Software Foundation</p> <p style="text-align: center; margin-top: 10px; color: #444">
    Contact us: Join QQ Group 659990460 | Add friend <i>tietouqiao</i> and be invited to Wechat Group<br>
    see <a href="https://github.com/apache/iotdb/issues/1995">Join the community</a> for more</p></main></div><div class="global-ui"></div></div>
    <script src="/assets/js/app.c6d1c98c.js" defer></script><script src="/assets/js/3.e95317f3.js" defer></script><script src="/assets/js/346.c6b949d6.js" defer></script>
  </body>
</html>