| (window.webpackJsonp=window.webpackJsonp||[]).push([[529],{924:function(s,e,n){"use strict";n.r(e);var a=n(29),t=Object(a.a)({},(function(){var s=this,e=s._self._c;return e("ContentSlotsDistributor",{attrs:{"slot-key":s.$parent.slotKey}},[e("h1",{attrs:{id:"查询性能追踪"}},[e("a",{staticClass:"header-anchor",attrs:{href:"#查询性能追踪"}},[s._v("#")]),s._v(" 查询性能追踪")]),s._v(" "),e("p",[s._v("IoTDB 支持使用 "),e("code",[s._v("TRACING")]),s._v(" 关键词对查询语句进行性能追踪。用户可以使用性能追踪工具来分析语句执行中存在的潜在性能问题。")]),s._v(" "),e("p",[s._v("性能追踪的结果包括：")]),s._v(" "),e("ol",[e("li",[s._v("查询执行过程中各个阶段的累积耗时。")]),s._v(" "),e("li",[s._v("与查询性能分析相关的统计信息，包括查询的时间序列数、涉及访问的 Tsfile 文件数、需要扫描的 chunk 总数以及平均每个 chunk 包含的数据点个数、读取的 Page 总数以及其中乱序 Page 的个数。")])]),s._v(" "),e("p",[s._v("例如执行 "),e("code",[s._v("tracing select * from root")]),s._v("，输出结果如下：")]),s._v(" "),e("div",{staticClass:"language- line-numbers-mode"},[e("pre",{pre:!0,attrs:{class:"language-text"}},[e("code",[s._v("Tracing Activties:\n+------------------------------------------------------+------------+\n| Activity|Elapsed Time|\n+------------------------------------------------------+------------+\n|Start to execute statement: tracing select * from root| 0|\n| Parse SQL to physical plan| 4|\n| Create and cache dataset| 16|\n| * Num of series paths: 3| |\n| * Num of sequence files read: 2| |\n| * Num of unsequence files read: 1| |\n| * Num of sequence chunks: 6, avg points: 100.0| |\n| * Num of unsequence chunks: 3, avg points: 100.0| |\n| * Num of Pages: 9, overlapped pages: 0 (0.0%)| |\n| Request complete| 20|\n+------------------------------------------------------+------------+\n")])]),s._v(" "),e("div",{staticClass:"line-numbers-wrapper"},[e("span",{staticClass:"line-number"},[s._v("1")]),e("br"),e("span",{staticClass:"line-number"},[s._v("2")]),e("br"),e("span",{staticClass:"line-number"},[s._v("3")]),e("br"),e("span",{staticClass:"line-number"},[s._v("4")]),e("br"),e("span",{staticClass:"line-number"},[s._v("5")]),e("br"),e("span",{staticClass:"line-number"},[s._v("6")]),e("br"),e("span",{staticClass:"line-number"},[s._v("7")]),e("br"),e("span",{staticClass:"line-number"},[s._v("8")]),e("br"),e("span",{staticClass:"line-number"},[s._v("9")]),e("br"),e("span",{staticClass:"line-number"},[s._v("10")]),e("br"),e("span",{staticClass:"line-number"},[s._v("11")]),e("br"),e("span",{staticClass:"line-number"},[s._v("12")]),e("br"),e("span",{staticClass:"line-number"},[s._v("13")]),e("br"),e("span",{staticClass:"line-number"},[s._v("14")]),e("br"),e("span",{staticClass:"line-number"},[s._v("15")]),e("br")])])])}),[],!1,null,null,null);e.default=t.exports}}]); |