<!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.9c03bb74.js" as="script"><link rel="preload" href="/assets/js/3.e95317f3.js" as="script"><link rel="preload" href="/assets/js/294.dbc158e3.js" as="script"><link rel="prefetch" href="/assets/js/10.77e7d27b.js"><link rel="prefetch" href="/assets/js/100.ce37c53f.js"><link rel="prefetch" href="/assets/js/101.ab370749.js"><link rel="prefetch" href="/assets/js/102.4db55384.js"><link rel="prefetch" href="/assets/js/103.28a00d56.js"><link rel="prefetch" href="/assets/js/104.aaf85214.js"><link rel="prefetch" href="/assets/js/105.eb973f15.js"><link rel="prefetch" href="/assets/js/106.007d9ae6.js"><link rel="prefetch" href="/assets/js/107.35199171.js"><link rel="prefetch" href="/assets/js/108.2f080778.js"><link rel="prefetch" href="/assets/js/109.4a3db7c3.js"><link rel="prefetch" href="/assets/js/11.242ea813.js"><link rel="prefetch" href="/assets/js/110.121c12b0.js"><link rel="prefetch" href="/assets/js/111.2d907f27.js"><link rel="prefetch" href="/assets/js/112.cd3fc3c6.js"><link rel="prefetch" href="/assets/js/113.60360e14.js"><link rel="prefetch" href="/assets/js/114.b1977cbf.js"><link rel="prefetch" href="/assets/js/115.71389e78.js"><link rel="prefetch" href="/assets/js/116.c495c800.js"><link rel="prefetch" href="/assets/js/117.f6a4a5d4.js"><link rel="prefetch" href="/assets/js/118.986551b6.js"><link rel="prefetch" href="/assets/js/119.ccf52dd9.js"><link rel="prefetch" href="/assets/js/12.643b0fb0.js"><link rel="prefetch" href="/assets/js/120.c21aafd0.js"><link rel="prefetch" href="/assets/js/121.448ace52.js"><link rel="prefetch" href="/assets/js/122.37b6650b.js"><link rel="prefetch" href="/assets/js/123.096531cd.js"><link rel="prefetch" href="/assets/js/124.6d8ba356.js"><link rel="prefetch" href="/assets/js/125.b053a479.js"><link rel="prefetch" href="/assets/js/126.32856698.js"><link rel="prefetch" href="/assets/js/127.211c2b9f.js"><link rel="prefetch" href="/assets/js/128.f7cd241a.js"><link rel="prefetch" href="/assets/js/129.8983f959.js"><link rel="prefetch" href="/assets/js/13.c58bffc8.js"><link rel="prefetch" href="/assets/js/130.27448489.js"><link rel="prefetch" href="/assets/js/131.f74784eb.js"><link rel="prefetch" href="/assets/js/132.9553fdd5.js"><link rel="prefetch" href="/assets/js/133.128c722a.js"><link rel="prefetch" href="/assets/js/134.3e480989.js"><link rel="prefetch" href="/assets/js/135.06b43884.js"><link rel="prefetch" href="/assets/js/136.6a6503c4.js"><link rel="prefetch" href="/assets/js/137.f79fb732.js"><link rel="prefetch" href="/assets/js/138.c519ee60.js"><link rel="prefetch" href="/assets/js/139.269b4122.js"><link rel="prefetch" href="/assets/js/14.939be0f9.js"><link rel="prefetch" href="/assets/js/140.8acac491.js"><link rel="prefetch" href="/assets/js/141.5739ba5c.js"><link rel="prefetch" href="/assets/js/142.0a0bb60d.js"><link rel="prefetch" href="/assets/js/143.2849d1b8.js"><link rel="prefetch" href="/assets/js/144.40806d0f.js"><link rel="prefetch" href="/assets/js/145.f396d071.js"><link rel="prefetch" href="/assets/js/146.3f935af5.js"><link rel="prefetch" href="/assets/js/147.6ab3b033.js"><link rel="prefetch" href="/assets/js/148.1e9ba5bb.js"><link rel="prefetch" href="/assets/js/149.be7d35fd.js"><link rel="prefetch" href="/assets/js/15.843fe861.js"><link rel="prefetch" href="/assets/js/150.4553bfe1.js"><link rel="prefetch" href="/assets/js/151.4df7c29e.js"><link rel="prefetch" href="/assets/js/152.7fbfa55b.js"><link rel="prefetch" href="/assets/js/153.b307a91f.js"><link rel="prefetch" href="/assets/js/154.61a099b6.js"><link rel="prefetch" href="/assets/js/155.42bd11f4.js"><link rel="prefetch" href="/assets/js/156.5e14d94b.js"><link rel="prefetch" href="/assets/js/157.a82e8d14.js"><link rel="prefetch" href="/assets/js/158.4ca4cf76.js"><link rel="prefetch" href="/assets/js/159.96ad00f0.js"><link rel="prefetch" href="/assets/js/16.17c1f643.js"><link rel="prefetch" href="/assets/js/160.d27a9f8e.js"><link rel="prefetch" href="/assets/js/161.f69489a3.js"><link rel="prefetch" href="/assets/js/162.d6297e81.js"><link rel="prefetch" href="/assets/js/163.8c7d6f48.js"><link rel="prefetch" href="/assets/js/164.844ec167.js"><link rel="prefetch" href="/assets/js/165.e4109536.js"><link rel="prefetch" href="/assets/js/166.6f922175.js"><link rel="prefetch" href="/assets/js/167.27cb7956.js"><link rel="prefetch" href="/assets/js/168.66d50e2f.js"><link rel="prefetch" href="/assets/js/169.db6a9c1e.js"><link rel="prefetch" href="/assets/js/17.a4028525.js"><link rel="prefetch" href="/assets/js/170.f09f4ab5.js"><link rel="prefetch" href="/assets/js/171.03b885f5.js"><link rel="prefetch" href="/assets/js/172.712c6bac.js"><link rel="prefetch" href="/assets/js/173.72a81752.js"><link rel="prefetch" href="/assets/js/174.80e57cad.js"><link rel="prefetch" href="/assets/js/175.96ef1cbc.js"><link rel="prefetch" href="/assets/js/176.975567d0.js"><link rel="prefetch" href="/assets/js/177.e46b5dad.js"><link rel="prefetch" href="/assets/js/178.277a4463.js"><link rel="prefetch" href="/assets/js/179.a8370836.js"><link rel="prefetch" href="/assets/js/18.122d5826.js"><link rel="prefetch" href="/assets/js/180.66ebf02a.js"><link rel="prefetch" href="/assets/js/181.b5488f9b.js"><link rel="prefetch" href="/assets/js/182.d354a8c6.js"><link rel="prefetch" href="/assets/js/183.87f069d1.js"><link rel="prefetch" href="/assets/js/184.47c2f6fb.js"><link rel="prefetch" href="/assets/js/185.b6a632b5.js"><link rel="prefetch" href="/assets/js/186.9f9a7452.js"><link rel="prefetch" href="/assets/js/187.aadc1931.js"><link rel="prefetch" href="/assets/js/188.90cc251e.js"><link rel="prefetch" href="/assets/js/189.01c9ecc3.js"><link rel="prefetch" href="/assets/js/19.9187dec1.js"><link rel="prefetch" href="/assets/js/190.ff15e49f.js"><link rel="prefetch" href="/assets/js/191.a47f90cd.js"><link rel="prefetch" href="/assets/js/192.1d1eb36e.js"><link rel="prefetch" href="/assets/js/193.39fab29d.js"><link rel="prefetch" href="/assets/js/194.f1cbfa0a.js"><link rel="prefetch" href="/assets/js/195.c40239c9.js"><link rel="prefetch" href="/assets/js/196.0388c356.js"><link rel="prefetch" href="/assets/js/197.55863e11.js"><link rel="prefetch" href="/assets/js/198.a48cc095.js"><link rel="prefetch" href="/assets/js/199.dae24824.js"><link rel="prefetch" href="/assets/js/20.c8df4732.js"><link rel="prefetch" href="/assets/js/200.5b971052.js"><link rel="prefetch" href="/assets/js/201.c6d6883b.js"><link rel="prefetch" href="/assets/js/202.56b1c573.js"><link rel="prefetch" href="/assets/js/203.cacf8999.js"><link rel="prefetch" href="/assets/js/204.899538ec.js"><link rel="prefetch" href="/assets/js/205.fd2fe361.js"><link rel="prefetch" href="/assets/js/206.ea246089.js"><link rel="prefetch" href="/assets/js/207.4dd0bdf9.js"><link rel="prefetch" href="/assets/js/208.30c94a7c.js"><link rel="prefetch" href="/assets/js/209.8d20aa77.js"><link rel="prefetch" href="/assets/js/21.acbfa763.js"><link rel="prefetch" href="/assets/js/210.ad8beb10.js"><link rel="prefetch" href="/assets/js/211.87928df0.js"><link rel="prefetch" href="/assets/js/212.552b3f7c.js"><link rel="prefetch" href="/assets/js/213.2b0a5283.js"><link rel="prefetch" href="/assets/js/214.8cf08cfc.js"><link rel="prefetch" href="/assets/js/215.d3564dd7.js"><link rel="prefetch" href="/assets/js/216.736e26f0.js"><link rel="prefetch" href="/assets/js/217.f9370757.js"><link rel="prefetch" href="/assets/js/218.3205fb4a.js"><link rel="prefetch" href="/assets/js/219.fd6ed6fa.js"><link rel="prefetch" href="/assets/js/22.1e7200c8.js"><link rel="prefetch" href="/assets/js/220.d72b3bb1.js"><link rel="prefetch" href="/assets/js/221.7e1fb00c.js"><link rel="prefetch" href="/assets/js/222.f520de95.js"><link rel="prefetch" href="/assets/js/223.494442ca.js"><link rel="prefetch" href="/assets/js/224.642062b0.js"><link rel="prefetch" href="/assets/js/225.9b6f0752.js"><link rel="prefetch" href="/assets/js/226.4868d0a5.js"><link rel="prefetch" href="/assets/js/227.6ba50795.js"><link rel="prefetch" href="/assets/js/228.96c32a84.js"><link rel="prefetch" href="/assets/js/229.79ec0103.js"><link rel="prefetch" href="/assets/js/23.91ba0b88.js"><link rel="prefetch" href="/assets/js/230.eb3c9a16.js"><link rel="prefetch" href="/assets/js/231.dc2fe2df.js"><link rel="prefetch" href="/assets/js/232.5a6632a5.js"><link rel="prefetch" href="/assets/js/233.f79fadcf.js"><link rel="prefetch" href="/assets/js/234.bd229dea.js"><link rel="prefetch" href="/assets/js/235.b9343eea.js"><link rel="prefetch" href="/assets/js/236.39a58653.js"><link rel="prefetch" href="/assets/js/237.d795e1ce.js"><link rel="prefetch" href="/assets/js/238.0357593a.js"><link rel="prefetch" href="/assets/js/239.a96f58b0.js"><link rel="prefetch" href="/assets/js/24.de37758e.js"><link rel="prefetch" href="/assets/js/240.5023ae7f.js"><link rel="prefetch" href="/assets/js/241.b8bfff76.js"><link rel="prefetch" href="/assets/js/242.1006f57d.js"><link rel="prefetch" href="/assets/js/243.177605aa.js"><link rel="prefetch" href="/assets/js/244.49b5cc23.js"><link rel="prefetch" href="/assets/js/245.26270fbd.js"><link rel="prefetch" href="/assets/js/246.5ddc708b.js"><link rel="prefetch" href="/assets/js/247.adc9b00e.js"><link rel="prefetch" href="/assets/js/248.0dddc45e.js"><link rel="prefetch" href="/assets/js/249.86245d4b.js"><link rel="prefetch" href="/assets/js/25.77e4633a.js"><link rel="prefetch" href="/assets/js/250.ca664993.js"><link rel="prefetch" href="/assets/js/251.4110130e.js"><link rel="prefetch" href="/assets/js/252.69e52586.js"><link rel="prefetch" href="/assets/js/253.6a0b34fb.js"><link rel="prefetch" href="/assets/js/254.6d43bbe7.js"><link rel="prefetch" href="/assets/js/255.ef51c14f.js"><link rel="prefetch" href="/assets/js/256.e30632ae.js"><link rel="prefetch" href="/assets/js/257.8474f813.js"><link rel="prefetch" href="/assets/js/258.f4b72fd8.js"><link rel="prefetch" href="/assets/js/259.f9b80571.js"><link rel="prefetch" href="/assets/js/26.bc913725.js"><link rel="prefetch" href="/assets/js/260.890c3824.js"><link rel="prefetch" href="/assets/js/261.7a0e64a4.js"><link rel="prefetch" href="/assets/js/262.f1795204.js"><link rel="prefetch" href="/assets/js/263.4645793a.js"><link rel="prefetch" href="/assets/js/264.cedced53.js"><link rel="prefetch" href="/assets/js/265.f5999224.js"><link rel="prefetch" href="/assets/js/266.796b7845.js"><link rel="prefetch" href="/assets/js/267.6a6e0b45.js"><link rel="prefetch" href="/assets/js/268.e31ccc5d.js"><link rel="prefetch" href="/assets/js/269.87ec3c50.js"><link rel="prefetch" href="/assets/js/27.353617df.js"><link rel="prefetch" href="/assets/js/270.10c1f626.js"><link rel="prefetch" href="/assets/js/271.951311af.js"><link rel="prefetch" href="/assets/js/272.b88b9e6e.js"><link rel="prefetch" href="/assets/js/273.60491e24.js"><link rel="prefetch" href="/assets/js/274.256ac066.js"><link rel="prefetch" href="/assets/js/275.bc626957.js"><link rel="prefetch" href="/assets/js/276.bf42d85f.js"><link rel="prefetch" href="/assets/js/277.195beb55.js"><link rel="prefetch" href="/assets/js/278.f7da5f89.js"><link rel="prefetch" href="/assets/js/279.6238db1e.js"><link rel="prefetch" href="/assets/js/28.0a801078.js"><link rel="prefetch" href="/assets/js/280.4a586292.js"><link rel="prefetch" href="/assets/js/281.2b5d75c2.js"><link rel="prefetch" href="/assets/js/282.d71dd9d3.js"><link rel="prefetch" href="/assets/js/283.39b9ec0e.js"><link rel="prefetch" href="/assets/js/284.306b0a13.js"><link rel="prefetch" href="/assets/js/285.8e9ec7da.js"><link rel="prefetch" href="/assets/js/286.4c15caa2.js"><link rel="prefetch" href="/assets/js/287.4b071b23.js"><link rel="prefetch" href="/assets/js/288.8b780706.js"><link rel="prefetch" href="/assets/js/289.789f44e7.js"><link rel="prefetch" href="/assets/js/29.015a0cef.js"><link rel="prefetch" href="/assets/js/290.faf33e36.js"><link rel="prefetch" href="/assets/js/291.7fe43457.js"><link rel="prefetch" href="/assets/js/292.e00b421d.js"><link rel="prefetch" href="/assets/js/293.010cbc8b.js"><link rel="prefetch" href="/assets/js/295.1e94dacc.js"><link rel="prefetch" href="/assets/js/296.77ae03d2.js"><link rel="prefetch" href="/assets/js/297.e548ba7e.js"><link rel="prefetch" href="/assets/js/298.9e64d086.js"><link rel="prefetch" href="/assets/js/299.a9495179.js"><link rel="prefetch" href="/assets/js/30.03cf4852.js"><link rel="prefetch" href="/assets/js/300.4a34e85e.js"><link rel="prefetch" href="/assets/js/301.646c292f.js"><link rel="prefetch" href="/assets/js/302.992ba1a4.js"><link rel="prefetch" href="/assets/js/303.2fa1659c.js"><link rel="prefetch" href="/assets/js/304.45ec5f49.js"><link rel="prefetch" href="/assets/js/305.c920feb8.js"><link rel="prefetch" href="/assets/js/306.9adbbd88.js"><link rel="prefetch" href="/assets/js/307.9236e6dd.js"><link rel="prefetch" href="/assets/js/308.f1153048.js"><link rel="prefetch" href="/assets/js/309.160e8998.js"><link rel="prefetch" href="/assets/js/31.9af92350.js"><link rel="prefetch" href="/assets/js/310.264c84d3.js"><link rel="prefetch" href="/assets/js/311.b0722a23.js"><link rel="prefetch" href="/assets/js/312.d6db71aa.js"><link rel="prefetch" href="/assets/js/313.56c40b4a.js"><link rel="prefetch" href="/assets/js/314.4430b382.js"><link rel="prefetch" href="/assets/js/315.c70120b9.js"><link rel="prefetch" href="/assets/js/316.f8399289.js"><link rel="prefetch" href="/assets/js/317.1de6d257.js"><link rel="prefetch" href="/assets/js/318.91c96271.js"><link rel="prefetch" href="/assets/js/319.eb7b75c1.js"><link rel="prefetch" href="/assets/js/32.e5e702b0.js"><link rel="prefetch" href="/assets/js/320.cc4206e7.js"><link rel="prefetch" href="/assets/js/321.a4b9d736.js"><link rel="prefetch" href="/assets/js/322.5aae6989.js"><link rel="prefetch" href="/assets/js/323.e4fd51b3.js"><link rel="prefetch" href="/assets/js/324.1ba3ee32.js"><link rel="prefetch" href="/assets/js/325.d92a5a32.js"><link rel="prefetch" href="/assets/js/326.176dd708.js"><link rel="prefetch" href="/assets/js/327.974ddc21.js"><link rel="prefetch" href="/assets/js/328.7be0fd73.js"><link rel="prefetch" href="/assets/js/329.c7ddf3b9.js"><link rel="prefetch" href="/assets/js/33.d0eafbb9.js"><link rel="prefetch" href="/assets/js/330.bd9e4aaa.js"><link rel="prefetch" href="/assets/js/331.0930a354.js"><link rel="prefetch" href="/assets/js/332.fb2e17c5.js"><link rel="prefetch" href="/assets/js/333.6a30384d.js"><link rel="prefetch" href="/assets/js/334.c3a65c90.js"><link rel="prefetch" href="/assets/js/335.925d4e40.js"><link rel="prefetch" href="/assets/js/336.d57e25c2.js"><link rel="prefetch" href="/assets/js/337.0231a5b2.js"><link rel="prefetch" href="/assets/js/338.6cda9f6a.js"><link rel="prefetch" href="/assets/js/339.bbf73c4f.js"><link rel="prefetch" href="/assets/js/34.85849ed4.js"><link rel="prefetch" href="/assets/js/340.f50cc5bc.js"><link rel="prefetch" href="/assets/js/341.bb11443e.js"><link rel="prefetch" href="/assets/js/342.0657d637.js"><link rel="prefetch" href="/assets/js/343.6757b598.js"><link rel="prefetch" href="/assets/js/344.eb356eae.js"><link rel="prefetch" href="/assets/js/345.e61fd7a0.js"><link rel="prefetch" href="/assets/js/346.cbfb04f4.js"><link rel="prefetch" href="/assets/js/347.38bbefab.js"><link rel="prefetch" href="/assets/js/348.53daceee.js"><link rel="prefetch" href="/assets/js/349.cf4bf014.js"><link rel="prefetch" href="/assets/js/35.5612ab6a.js"><link rel="prefetch" href="/assets/js/350.1066134b.js"><link rel="prefetch" href="/assets/js/351.70c60d7d.js"><link rel="prefetch" href="/assets/js/352.38c78131.js"><link rel="prefetch" href="/assets/js/353.8c271a83.js"><link rel="prefetch" href="/assets/js/354.f07fe232.js"><link rel="prefetch" href="/assets/js/355.75b97cf0.js"><link rel="prefetch" href="/assets/js/356.7e54a7f7.js"><link rel="prefetch" href="/assets/js/357.186ba021.js"><link rel="prefetch" href="/assets/js/358.239bc6cd.js"><link rel="prefetch" href="/assets/js/359.5b5efbc0.js"><link rel="prefetch" href="/assets/js/36.5a401e9f.js"><link rel="prefetch" href="/assets/js/360.dc8c37e4.js"><link rel="prefetch" href="/assets/js/361.0ffc00b2.js"><link rel="prefetch" href="/assets/js/362.0b44b216.js"><link rel="prefetch" href="/assets/js/363.957ae19e.js"><link rel="prefetch" href="/assets/js/364.f744f1cf.js"><link rel="prefetch" href="/assets/js/365.228a2005.js"><link rel="prefetch" href="/assets/js/366.6dc37394.js"><link rel="prefetch" href="/assets/js/367.56ff065b.js"><link rel="prefetch" href="/assets/js/368.9689ca0c.js"><link rel="prefetch" href="/assets/js/369.ed6d9c14.js"><link rel="prefetch" href="/assets/js/37.692720e1.js"><link rel="prefetch" href="/assets/js/370.584442b6.js"><link rel="prefetch" href="/assets/js/371.770d40de.js"><link rel="prefetch" href="/assets/js/372.6b44d26d.js"><link rel="prefetch" href="/assets/js/373.4548d4c0.js"><link rel="prefetch" href="/assets/js/374.e347ead4.js"><link rel="prefetch" href="/assets/js/375.774420c2.js"><link rel="prefetch" href="/assets/js/376.4b504e94.js"><link rel="prefetch" href="/assets/js/377.e3d4af2c.js"><link rel="prefetch" href="/assets/js/378.8265e3af.js"><link rel="prefetch" href="/assets/js/379.06514b26.js"><link rel="prefetch" href="/assets/js/38.eebc30e0.js"><link rel="prefetch" href="/assets/js/380.413183d4.js"><link rel="prefetch" href="/assets/js/381.570e7c14.js"><link rel="prefetch" href="/assets/js/382.6e94a17d.js"><link rel="prefetch" href="/assets/js/383.ab06426d.js"><link rel="prefetch" href="/assets/js/384.8cde732c.js"><link rel="prefetch" href="/assets/js/385.edbe545d.js"><link rel="prefetch" href="/assets/js/386.5edbd64b.js"><link rel="prefetch" href="/assets/js/387.d08b9da1.js"><link rel="prefetch" href="/assets/js/388.3cafa76f.js"><link rel="prefetch" href="/assets/js/389.ac1c71b5.js"><link rel="prefetch" href="/assets/js/39.9ccd0236.js"><link rel="prefetch" href="/assets/js/390.e3c6dc5b.js"><link rel="prefetch" href="/assets/js/391.097ce5d5.js"><link rel="prefetch" href="/assets/js/392.6c36a3c8.js"><link rel="prefetch" href="/assets/js/393.cc10c814.js"><link rel="prefetch" href="/assets/js/394.0f496e89.js"><link rel="prefetch" href="/assets/js/395.829eba9f.js"><link rel="prefetch" href="/assets/js/396.3ff26d83.js"><link rel="prefetch" href="/assets/js/397.bee7fd8b.js"><link rel="prefetch" href="/assets/js/398.812712cf.js"><link rel="prefetch" href="/assets/js/399.359fa7fe.js"><link rel="prefetch" href="/assets/js/4.9c4b1c6d.js"><link rel="prefetch" href="/assets/js/40.78497aeb.js"><link rel="prefetch" href="/assets/js/400.39779156.js"><link rel="prefetch" href="/assets/js/401.df776005.js"><link rel="prefetch" href="/assets/js/402.be1f5783.js"><link rel="prefetch" href="/assets/js/403.8856d7b1.js"><link rel="prefetch" href="/assets/js/404.562089b0.js"><link rel="prefetch" href="/assets/js/405.93f42baf.js"><link rel="prefetch" href="/assets/js/406.8dbc7179.js"><link rel="prefetch" href="/assets/js/407.ab430854.js"><link rel="prefetch" href="/assets/js/408.78190c9f.js"><link rel="prefetch" href="/assets/js/409.5885c231.js"><link rel="prefetch" href="/assets/js/41.f483212d.js"><link rel="prefetch" href="/assets/js/410.b081220a.js"><link rel="prefetch" href="/assets/js/411.a36444c4.js"><link rel="prefetch" href="/assets/js/412.ceb1c2f9.js"><link rel="prefetch" href="/assets/js/413.9a587755.js"><link rel="prefetch" href="/assets/js/414.76fbf607.js"><link rel="prefetch" href="/assets/js/415.4dcc07c7.js"><link rel="prefetch" href="/assets/js/416.67a151b4.js"><link rel="prefetch" href="/assets/js/417.8f1f6147.js"><link rel="prefetch" href="/assets/js/418.d5fc9d05.js"><link rel="prefetch" href="/assets/js/419.540dcd2a.js"><link rel="prefetch" href="/assets/js/42.ffb032af.js"><link rel="prefetch" href="/assets/js/420.6e0a10f2.js"><link rel="prefetch" href="/assets/js/421.a6c3c8af.js"><link rel="prefetch" href="/assets/js/422.47653244.js"><link rel="prefetch" href="/assets/js/423.cb7eba6d.js"><link rel="prefetch" href="/assets/js/424.9d5aa304.js"><link rel="prefetch" href="/assets/js/425.d2f6e40e.js"><link rel="prefetch" href="/assets/js/426.d6deb76a.js"><link rel="prefetch" href="/assets/js/427.d39d619c.js"><link rel="prefetch" href="/assets/js/428.6e4e5abb.js"><link rel="prefetch" href="/assets/js/429.0f2edacf.js"><link rel="prefetch" href="/assets/js/43.7406f914.js"><link rel="prefetch" href="/assets/js/430.ddcfba32.js"><link rel="prefetch" href="/assets/js/431.5ecf6e5d.js"><link rel="prefetch" href="/assets/js/432.b578015e.js"><link rel="prefetch" href="/assets/js/433.90540732.js"><link rel="prefetch" href="/assets/js/434.04a8d2c6.js"><link rel="prefetch" href="/assets/js/435.959e7362.js"><link rel="prefetch" href="/assets/js/436.891b6ce7.js"><link rel="prefetch" href="/assets/js/437.7c983dad.js"><link rel="prefetch" href="/assets/js/438.f7e133f1.js"><link rel="prefetch" href="/assets/js/439.692da598.js"><link rel="prefetch" href="/assets/js/44.3bea749e.js"><link rel="prefetch" href="/assets/js/440.2971f4ef.js"><link rel="prefetch" href="/assets/js/441.e12292fb.js"><link rel="prefetch" href="/assets/js/442.08f60114.js"><link rel="prefetch" href="/assets/js/443.9f684f2a.js"><link rel="prefetch" href="/assets/js/444.d100eb74.js"><link rel="prefetch" href="/assets/js/445.733e07b3.js"><link rel="prefetch" href="/assets/js/446.b1a5daaf.js"><link rel="prefetch" href="/assets/js/447.b565b8e7.js"><link rel="prefetch" href="/assets/js/448.c4d1c15e.js"><link rel="prefetch" href="/assets/js/449.f9f855be.js"><link rel="prefetch" href="/assets/js/45.4f6dc502.js"><link rel="prefetch" href="/assets/js/450.3ff3ce7b.js"><link rel="prefetch" href="/assets/js/451.f43857ff.js"><link rel="prefetch" href="/assets/js/452.3a8bb15a.js"><link rel="prefetch" href="/assets/js/453.4d5d4319.js"><link rel="prefetch" href="/assets/js/454.e0838804.js"><link rel="prefetch" href="/assets/js/455.86256c6f.js"><link rel="prefetch" href="/assets/js/456.98d95ce5.js"><link rel="prefetch" href="/assets/js/457.27f821d2.js"><link rel="prefetch" href="/assets/js/458.0e11d249.js"><link rel="prefetch" href="/assets/js/459.6b8af96a.js"><link rel="prefetch" href="/assets/js/46.e460983d.js"><link rel="prefetch" href="/assets/js/460.5294a47f.js"><link rel="prefetch" href="/assets/js/461.5cb7cfb1.js"><link rel="prefetch" href="/assets/js/462.214e91ce.js"><link rel="prefetch" href="/assets/js/463.54494074.js"><link rel="prefetch" href="/assets/js/464.0e1615f7.js"><link rel="prefetch" href="/assets/js/465.c61d57fa.js"><link rel="prefetch" href="/assets/js/466.88c375a9.js"><link rel="prefetch" href="/assets/js/467.b3f00de3.js"><link rel="prefetch" href="/assets/js/468.8f2561ff.js"><link rel="prefetch" href="/assets/js/469.741b348f.js"><link rel="prefetch" href="/assets/js/47.e56ee397.js"><link rel="prefetch" href="/assets/js/470.ba1d5a08.js"><link rel="prefetch" href="/assets/js/471.9842c3d9.js"><link rel="prefetch" href="/assets/js/472.887667b1.js"><link rel="prefetch" href="/assets/js/473.ac9f4dc8.js"><link rel="prefetch" href="/assets/js/474.7ab2ad2f.js"><link rel="prefetch" href="/assets/js/475.04c8df23.js"><link rel="prefetch" href="/assets/js/476.369e6ad4.js"><link rel="prefetch" href="/assets/js/477.cd44b6c4.js"><link rel="prefetch" href="/assets/js/478.1c4e292d.js"><link rel="prefetch" href="/assets/js/479.18311c46.js"><link rel="prefetch" href="/assets/js/48.bec9faeb.js"><link rel="prefetch" href="/assets/js/480.6a119ed5.js"><link rel="prefetch" href="/assets/js/481.6504abc3.js"><link rel="prefetch" href="/assets/js/482.a0850ad4.js"><link rel="prefetch" href="/assets/js/483.11c430e0.js"><link rel="prefetch" href="/assets/js/484.cb6bc4a3.js"><link rel="prefetch" href="/assets/js/485.fef6bd3e.js"><link rel="prefetch" href="/assets/js/486.9cbb009e.js"><link rel="prefetch" href="/assets/js/487.bf3ac79b.js"><link rel="prefetch" href="/assets/js/488.cdeb35a5.js"><link rel="prefetch" href="/assets/js/489.dad79eab.js"><link rel="prefetch" href="/assets/js/49.f271ac34.js"><link rel="prefetch" href="/assets/js/490.61225193.js"><link rel="prefetch" href="/assets/js/491.862665a1.js"><link rel="prefetch" href="/assets/js/492.e16d11e1.js"><link rel="prefetch" href="/assets/js/493.83997cf9.js"><link rel="prefetch" href="/assets/js/494.607eaccf.js"><link rel="prefetch" href="/assets/js/495.47d53a9a.js"><link rel="prefetch" href="/assets/js/496.166c88c4.js"><link rel="prefetch" href="/assets/js/497.3b9635e2.js"><link rel="prefetch" href="/assets/js/498.8e8025ec.js"><link rel="prefetch" href="/assets/js/499.22f6be18.js"><link rel="prefetch" href="/assets/js/5.2a4451ec.js"><link rel="prefetch" href="/assets/js/50.e60dabfc.js"><link rel="prefetch" href="/assets/js/500.517d8628.js"><link rel="prefetch" href="/assets/js/501.c5ae8bda.js"><link rel="prefetch" href="/assets/js/502.3dc27869.js"><link rel="prefetch" href="/assets/js/503.d6cc184c.js"><link rel="prefetch" href="/assets/js/504.203d7395.js"><link rel="prefetch" href="/assets/js/505.6cf56773.js"><link rel="prefetch" href="/assets/js/506.ccaa022c.js"><link rel="prefetch" href="/assets/js/507.1fc56592.js"><link rel="prefetch" href="/assets/js/508.1250eed8.js"><link rel="prefetch" href="/assets/js/509.a1a7285a.js"><link rel="prefetch" href="/assets/js/51.fd01b1a1.js"><link rel="prefetch" href="/assets/js/510.de535a70.js"><link rel="prefetch" href="/assets/js/511.c6a7f5d8.js"><link rel="prefetch" href="/assets/js/512.dca82ab9.js"><link rel="prefetch" href="/assets/js/513.8d501ad4.js"><link rel="prefetch" href="/assets/js/514.b07be8d6.js"><link rel="prefetch" href="/assets/js/515.9ea728dd.js"><link rel="prefetch" href="/assets/js/516.3cccca96.js"><link rel="prefetch" href="/assets/js/517.1d7ee046.js"><link rel="prefetch" href="/assets/js/518.05cb30e8.js"><link rel="prefetch" href="/assets/js/519.f838c1ca.js"><link rel="prefetch" href="/assets/js/52.c17bb00d.js"><link rel="prefetch" href="/assets/js/520.e41e66ce.js"><link rel="prefetch" href="/assets/js/521.4726d233.js"><link rel="prefetch" href="/assets/js/522.045aff30.js"><link rel="prefetch" href="/assets/js/523.9d9b45b5.js"><link rel="prefetch" href="/assets/js/524.9ff01ede.js"><link rel="prefetch" href="/assets/js/525.ba766db5.js"><link rel="prefetch" href="/assets/js/526.9f70e3c0.js"><link rel="prefetch" href="/assets/js/527.1af75ed9.js"><link rel="prefetch" href="/assets/js/528.85194f33.js"><link rel="prefetch" href="/assets/js/529.7f05b847.js"><link rel="prefetch" href="/assets/js/53.f69e6824.js"><link rel="prefetch" href="/assets/js/530.4f9b779c.js"><link rel="prefetch" href="/assets/js/531.54b0ee66.js"><link rel="prefetch" href="/assets/js/532.7107ab4b.js"><link rel="prefetch" href="/assets/js/54.29e4a381.js"><link rel="prefetch" href="/assets/js/55.9d4b8667.js"><link rel="prefetch" href="/assets/js/56.00691552.js"><link rel="prefetch" href="/assets/js/57.c942381a.js"><link rel="prefetch" href="/assets/js/58.89130d49.js"><link rel="prefetch" href="/assets/js/59.f0da0bf3.js"><link rel="prefetch" href="/assets/js/6.3450075a.js"><link rel="prefetch" href="/assets/js/60.53b7d88b.js"><link rel="prefetch" href="/assets/js/61.b70ccd57.js"><link rel="prefetch" href="/assets/js/62.ca60798b.js"><link rel="prefetch" href="/assets/js/63.ba337fc9.js"><link rel="prefetch" href="/assets/js/64.ed6b77b6.js"><link rel="prefetch" href="/assets/js/65.1dbdb0ee.js"><link rel="prefetch" href="/assets/js/66.aa4ead2c.js"><link rel="prefetch" href="/assets/js/67.29edf638.js"><link rel="prefetch" href="/assets/js/68.b614ca3d.js"><link rel="prefetch" href="/assets/js/69.8f65fe0a.js"><link rel="prefetch" href="/assets/js/7.c5c54fb4.js"><link rel="prefetch" href="/assets/js/70.dade9939.js"><link rel="prefetch" href="/assets/js/71.dbdc4216.js"><link rel="prefetch" href="/assets/js/72.37c2db55.js"><link rel="prefetch" href="/assets/js/73.40fb8290.js"><link rel="prefetch" href="/assets/js/74.6fb3093b.js"><link rel="prefetch" href="/assets/js/75.d96505fe.js"><link rel="prefetch" href="/assets/js/76.9c4f055c.js"><link rel="prefetch" href="/assets/js/77.3c1e294c.js"><link rel="prefetch" href="/assets/js/78.202bcf6c.js"><link rel="prefetch" href="/assets/js/79.4e6d41b0.js"><link rel="prefetch" href="/assets/js/8.68d2fe5c.js"><link rel="prefetch" href="/assets/js/80.8358bd99.js"><link rel="prefetch" href="/assets/js/81.b603dd42.js"><link rel="prefetch" href="/assets/js/82.bebbea34.js"><link rel="prefetch" href="/assets/js/83.764d566c.js"><link rel="prefetch" href="/assets/js/84.4867883c.js"><link rel="prefetch" href="/assets/js/85.bfe2dffd.js"><link rel="prefetch" href="/assets/js/86.0d9031f6.js"><link rel="prefetch" href="/assets/js/87.88112820.js"><link rel="prefetch" href="/assets/js/88.208d123f.js"><link rel="prefetch" href="/assets/js/89.75ed1194.js"><link rel="prefetch" href="/assets/js/9.e94d434b.js"><link rel="prefetch" href="/assets/js/90.7f184d9a.js"><link rel="prefetch" href="/assets/js/91.6595997c.js"><link rel="prefetch" href="/assets/js/92.791938c3.js"><link rel="prefetch" href="/assets/js/93.8bd8d987.js"><link rel="prefetch" href="/assets/js/94.0e7734d3.js"><link rel="prefetch" href="/assets/js/95.45187f8f.js"><link rel="prefetch" href="/assets/js/96.6b29372c.js"><link rel="prefetch" href="/assets/js/97.7eaeb339.js"><link rel="prefetch" href="/assets/js/98.391d8ef3.js"><link rel="prefetch" href="/assets/js/99.8e370fea.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/Get Started/QuickStart.html" class="nav-link">In progress</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/GroupByQuery.html" class="nav-link">English</a></li><li class="dropdown-item"><!----> <a href="/zh/SystemDesign/DataQuery/GroupByQuery.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/Get Started/QuickStart.html" class="nav-link">In progress</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/GroupByQuery.html" class="nav-link">English</a></li><li class="dropdown-item"><!----> <a href="/zh/SystemDesign/DataQuery/GroupByQuery.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" aria-current="page" class="active sidebar-link">降采样查询</a></li><li><a href="/zh/SystemDesign/DataQuery/LastQuery.html" class="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="降采样查询"><a href="#降采样查询" class="header-anchor">#</a> 降采样查询</h1> <ul><li>org.apache.iotdb.db.query.dataset.groupby.GroupByEngineDataSet</li></ul> <p>降采样查询的结果集都会继承 <code>GroupByEngineDataSet</code>，该类包含如下字段：</p> <ul><li>protected long queryId</li> <li>private long interval</li> <li>private long slidingStep</li></ul> <p>以下两个字段针对整个查询，时间段为左闭右开，即 <code>[startTime, endTime)</code>：</p> <ul><li>private long startTime</li> <li>private long endTime</li></ul> <p>以下字段针对当前分段，时间段为左闭右开，即 <code>[curStartTime, curEndTime)</code></p> <ul><li>protected long curStartTime;</li> <li>protected long curEndTime;</li> <li>private int usedIndex;</li> <li>protected boolean hasCachedTimeInterval;</li></ul> <p><code>GroupByEngineDataSet</code> 的核心方法很容易，首先根据是否有缓存的时间段判断是否有下一分段，有则返回 <code>true</code>；如果没有就计算分段开始时间，将 <code>usedIndex</code> 增加1。如果分段开始时间已经超过了查询结束时间，返回 <code>false</code>，否则计算查询结束时间，将 <code>hasCachedTimeInterval</code> 置为<code>true</code>，并返回 <code>true</code>：</p> <div class="language- line-numbers-mode"><pre class="language-text"><code>protected boolean hasNextWithoutConstraint() {
  if (hasCachedTimeInterval) {
    return true;
  }

  curStartTime = usedIndex * slidingStep + startTime;
  usedIndex++;
  if (curStartTime &lt; endTime) {
    hasCachedTimeInterval = true;
    curEndTime = Math.min(curStartTime + interval, endTime);
    return true;
  } else {
    return false;
  }
}
</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></div></div><h2 id="不带值过滤条件的降采样查询"><a href="#不带值过滤条件的降采样查询" class="header-anchor">#</a> 不带值过滤条件的降采样查询</h2> <p>不带值过滤条件的降采样查询逻辑主要在 <code>GroupByWithoutValueFilterDataSet</code> 类中，该类继承了 <code>GroupByEngineDataSet</code>。</p> <p>该类有如下关键字段：</p> <ul><li><p>private Map&lt;Path, GroupByExecutor&gt; pathExecutors 针对于相同 <code>Path</code> 的聚合函数进行归类，并封装成 <code>GroupByExecutor</code> ,
<code>GroupByExecutor</code> 封装了每个 <code>Path</code> 的数据计算逻辑和方法，在后面介绍</p></li> <li><p>private TimeRange timeRange 将每次计算的时间区间封装成对象，用于判断 <code>Statistics</code> 是否可以直接参与计算</p></li> <li><p>private Filter timeFilter   将用户定义的查询区间生成为 <code>Filter</code> 对象，用来过滤可用的<code>文件</code>、<code>chunk</code>、<code>page</code></p></li></ul> <p>首先，在初始化 <code>initGroupBy()</code> 方法中，根据表达式计算出 <code>timeFilter</code>，并为每个 <code>path</code> 生成 <code>GroupByExecutor</code> 。</p> <p><code>nextWithoutConstraint()</code> 方法通过调用 <code>GroupByExecutor.calcResult()</code> 方法计算出每个 <code>Path</code> 内的所有聚合方法的聚合值 <code>aggregateResults</code>。
以下方法用于将结果列表转化为 RowRecord，需要注意列表中没有结果时， RowRecord 中添加 <code>null</code>：</p> <div class="language- line-numbers-mode"><pre class="language-text"><code>for (AggregateResult res : fields) {
  if (res == null) {
    record.addField(null);
    continue;
  }
  record.addField(res.getResult(), res.getResultDataType());
}
</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></div></div><h3 id="groupbyexecutor"><a href="#groupbyexecutor" class="header-anchor">#</a> GroupByExecutor</h3> <p>封装了相同 path 下的所有聚合函数的计算方法，该类有如下关键字段：</p> <ul><li>private IAggregateReader reader 读取当前 <code>Path</code> 数据用到的 <code>SeriesAggregateReader</code></li> <li>private BatchData preCachedData 每次从 <code>Reader</code> 读取的数据是一批，很有可能会超过当前的时间段，那么这个 <code>BatchData</code> 就会被缓存留给下一次使用</li> <li>private List&lt;Pair&lt;AggregateResult, Integer&gt;&gt; results 存储了当前 <code>Path</code> 里所有的聚合方法，
例如：<code>select count(a),sum(a),avg(b)</code> ，<code>count</code> 和 <code>sum</code> 方法就被存到一起。
右侧的 <code>Integer</code> 用于结果集转化为RowRecord之前，需要将其顺序还原为用户查询的顺序。</li></ul> <h4 id="主要方法"><a href="#主要方法" class="header-anchor">#</a> 主要方法</h4> <div class="language- line-numbers-mode"><pre class="language-text"><code>//从 reader 中读取数据，并计算，该类的主方法。
private List&lt;Pair&lt;AggregateResult, Integer&gt;&gt; calcResult() throws IOException, QueryProcessException;

//添加当前 path 的聚合操作
private void addAggregateResult(AggregateResult aggrResult, int index);

//判断当前 path 是否已经完成了所有的聚合计算
private boolean isEndCalc();

//从上次计算没有使用完缓存的 BatchData 中计算结果
private boolean calcFromCacheData() throws IOException;

//使用 BatchData 计算
private void calcFromBatch(BatchData batchData) throws IOException;

//使用 Page 或 Chunk 的 Statistics 信息直接计算结果
private void calcFromStatistics(Statistics statistics) throws QueryProcessException;

//清空所有计算结果
private void resetAggregateResults();

//遍历并计算 page 中的数据
private boolean readAndCalcFromPage() throws IOException, QueryProcessException;

</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><p><code>GroupByExecutor</code> 中因为相同 <code>path</code> 的不同聚合函数使用的数据是相同的，所以在入口方法 <code>calcResult</code> 中负责读取该 <code>Path</code> 的所有数据,
取出来的数据再调用 <code>calcFromBatch</code> 方法完成遍历所有聚合函数对 <code>BatchData</code> 的计算。</p> <p><code>calcResult</code> 方法返回当前 Path 下的所有AggregateResult，以及当前聚合值在用户查询顺序里的位置，其主要逻辑：</p> <div class="language- line-numbers-mode"><pre class="language-text"><code>//把上次遗留的数据先做计算，如果能直接获得结果就结束计算
if (calcFromCacheData()) {
    return results;
}

//因为一个chunk是包含多个page的，那么必须先使用完当前chunk的page，再打开下一个chunk
if (readAndCalcFromPage()) {
    return results;
}

//遗留的数据如果计算完了就要打开新的chunk继续计算
while (reader.hasNextChunk()) {
    Statistics chunkStatistics = reader.currentChunkStatistics();
      // 判断能否使用 Statistics，并执行计算
       ....
      // 跳过当前chunk
      reader.skipCurrentChunk();
      // 如果已经获取到了所有结果就结束计算
      if (isEndCalc()) {
        return true;
      }
      continue;
    }
    //如果不能使用 chunkStatistics 就需要使用page数据计算
    if (readAndCalcFromPage()) {
      return results;
    }
}
</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><span class="line-number">25</span><br><span class="line-number">26</span><br><span class="line-number">27</span><br><span class="line-number">28</span><br></div></div><p><code>readAndCalcFromPage</code> 方法是从当前打开的chunk中获取page的数据，并计算聚合结果。当完成所有计算时返回 true，否则返回 false。主要逻辑：</p> <div class="language- line-numbers-mode"><pre class="language-text"><code>while (reader.hasNextPage()) {
    Statistics pageStatistics = reader.currentPageStatistics();
    //只有page与其它page不相交时，才能使用 pageStatistics
    if (pageStatistics != null) {
        // 判断能否使用 Statistics，并执行计算
        ....
        // 跳过当前page
        reader.skipCurrentPage();
        // 如果已经获取到了所有结果就结束计算
        if (isEndCalc()) {
          return true;
        }
        continue;
      }
    }
    // 不能使用 Statistics 时，只能取出所有数据进行计算
    BatchData batchData = reader.nextPage();
    if (batchData == null || !batchData.hasCurrent()) {
      continue;
    }
    // 如果刚打开的page就超过时间范围，缓存取出来的数据并直接结束计算
    if (batchData.currentTime() &gt;= curEndTime) {
      preCachedData = batchData;
      return true;
    }
    //执行计算
    calcFromBatch(batchData);
    ...
}

</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><span class="line-number">25</span><br><span class="line-number">26</span><br><span class="line-number">27</span><br><span class="line-number">28</span><br><span class="line-number">29</span><br><span class="line-number">30</span><br></div></div><p><code>calcFromBatch</code> 方法是对于取出的BatchData数据，遍历所有聚合函数进行计算，主要逻辑为：</p> <div class="language- line-numbers-mode"><pre class="language-text"><code>for (Pair&lt;AggregateResult, Integer&gt; result : results) {
    //如果某个函数已经完成了计算，就不在进行计算了，比如最小值这种计算
    if (result.left.isCalculatedAggregationResult()) {
      continue;
    }
    // 执行计算
    ....
}
//判断当前的 batchdata 里的数据是否还能被下次使用，如果能则加到缓存中
if (batchData.getMaxTimestamp() &gt;= curEndTime) {
    preCachedData = batchData;
}
</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></div></div><h2 id="带值过滤条件的聚合查询"><a href="#带值过滤条件的聚合查询" class="header-anchor">#</a> 带值过滤条件的聚合查询</h2> <p>带值过滤条件的降采样查询逻辑主要在 <code>GroupByWithValueFilterDataSet</code> 类中，该类继承了 <code>GroupByEngineDataSet</code>。</p> <p>该类有如下关键字段：</p> <ul><li><div class="language- line-numbers-mode"><pre class="language-text"><code>private List&lt;IReaderByTimestamp&gt; allDataReaderList
</code></pre> <div class="line-numbers-wrapper"><span class="line-number">1</span><br></div></div></li> <li><p>private GroupByPlan groupByTimePlan</p></li> <li><p>private TimeGenerator timestampGenerator</p></li> <li><p>private long timestamp 用于为下一个 group by 分区缓存 timestamp</p></li> <li><p>private boolean hasCachedTimestamp 用于判断是否有为下一个 group by 分区缓存 timestamp</p></li> <li><p>private int timeStampFetchSize 是 group by 计算 batch 的大小</p></li></ul> <p>首先，在初始化 <code>initGroupBy()</code> 方法中，根据表达式创建 <code>timestampGenerator</code>；然后为每一个时间序列创建一个 <code>SeriesReaderByTimestamp</code>，放到 <code>allDataReaderList</code>列表中</p> <p>初始化完成后，调用 <code>nextWithoutConstraint()</code> 方法更新结果。如果有为下一个 group by 分区缓存 timestamp，且时间符合要求，则将其加入 <code>timestampArray</code> 中，否则直接返回 <code>aggregateResultList</code> 结果；在没有为下一个 group by 分区缓存 timestamp 的情况下，使用 <code>timestampGenerator</code> 进行遍历：</p> <div class="language- line-numbers-mode"><pre class="language-text"><code>while (timestampGenerator.hasNext()) {
  // 调用 constructTimeArrayForOneCal() 方法，得到 timestamp 列表
  timeArrayLength = constructTimeArrayForOneCal(timestampArray, timeArrayLength);

  // 调用 updateResultUsingTimestamps() 方法，使用 timestamp 列表计算聚合结果
  for (int i = 0; i &lt; paths.size(); i++) {
    aggregateResultList.get(i).updateResultUsingTimestamps(
        timestampArray, timeArrayLength, allDataReaderList.get(i));
  }

  timeArrayLength = 0;
  // 判断是否到结束
  if (timestamp &gt;= curEndTime) {
    hasCachedTimestamp = true;
    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></div></div><p>其中的 <code>constructTimeArrayForOneCal()</code> 方法遍历 timestampGenerator 构建 timestamp 列表：</p> <div class="language- line-numbers-mode"><pre class="language-text"><code>for (int cnt = 1; cnt &lt; timeStampFetchSize &amp;&amp; timestampGenerator.hasNext(); cnt++) {
  timestamp = timestampGenerator.next();
  if (timestamp &lt; curEndTime) {
    timestampArray[timeArrayLength++] = timestamp;
  } else {
    hasCachedTimestamp = true;
    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></div></div><h2 id="使用level来汇总降采样的总点数"><a href="#使用level来汇总降采样的总点数" class="header-anchor">#</a> 使用Level来汇总降采样的总点数</h2> <p>降采样后，我们也可以使用level关键字来进一步汇总点数。</p> <p>这个逻辑在 <code>GroupByTimeDataSet</code>类里。</p> <ol><li><p>首先，把所有涉及到的时序按level来进行汇集，最后的路径。</p> <blockquote><p>例如把root.sg1.d1.s0,root.sg1.d2.s1按level=1汇集成root.sg1。</p></blockquote></li> <li><p>然后调用上述的降采样逻辑求出所有时序的总点数信息，这个会返回RowRecord数据结构。</p></li> <li><p>最后，把降采样返回的RowRecord按上述的final paths，进行累加，组合成新的RowRecord。</p> <blockquote><p>例如，把《root.sg1.d1.s0,3》，《root.sg1.d2.s1，4》聚合成《root.sg1，7》</p></blockquote></li></ol> <blockquote><p>注意:</p> <ol><li>这里只支持count操作</li> <li>root的层级level=0</li></ol></blockquote></div> <div class="page-nav"><p class="inner"><span class="prev">
        ←
        <a href="/zh/SystemDesign/DataQuery/AggregationQuery.html" class="prev">
          聚合查询
        </a></span> <span class="next"><a href="/zh/SystemDesign/DataQuery/LastQuery.html">
          最近时间戳 Last 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.9c03bb74.js" defer></script><script src="/assets/js/3.e95317f3.js" defer></script><script src="/assets/js/294.dbc158e3.js" defer></script>
  </body>
</html>