v$sql,v$sqlarea,v$sqltext 和 v$sql_plan 說明
一. 先看官網對這幾個檢視的說明（ORACLE 11gR2）
1.1 V$SQL
V$SQL lists statistics
on shared SQL areas without the
GROUP BYclause and
contains one row for each child of the original SQL text entered.
Statistics displayed in
V$SQL are normally updated at the end of query execution.
However, for long running queries, they are updated every 5 seconds.
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Column |
Datatype |
Description |
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First thousand characters of the SQL text for the current cursor |
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Full text for the SQL statement exposed as a
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SQL identifier of the parent cursor in the library cache |
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Amount of shared memory used by the child cursor (in bytes) |
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Fixed amount of memory used for the lifetime of the child cursor (in bytes) |
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Fixed amount of memory required during the execution of the child cursor |
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Number of sorts that were done for the child cursor |
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Indicates whether the context heap is loaded ( |
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Indicates whether the child cursor is locked ( |
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Number of users executing the statement |
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Number of fetches associated with the SQL statement |
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Number of executions that took place on this object since it was brought into the library cache |
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Total number of executions performed by parallel execution servers ( |
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Number of times this cursor was fully executed since the cursor was brought into
the library cache. The value of this statistic is not incremented when the cursor is partially executed, either because it failed during the execution or because only the first few rows produced by this cursor are fetched before the cursor is closed or re-executed.
By definition, the value of the |
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Number of users executing the statement |
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Number of times the object was either loaded or reloaded |
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Timestamp of the parent creation time |
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Number of times this child cursor has been invalidated |
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Number of parse calls for this child cursor |
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Number of disk reads for this child cursor |
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Number of direct writes for this child cursor |
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Number of buffer gets for this child cursor |
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Application wait time (in microseconds) |
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Concurrency wait time (in microseconds) |
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Cluster wait time (in microseconds) |
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User I/O Wait Time (in microseconds) |
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PL/SQL execution time (in microseconds) |
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Java execution time (in microseconds) |
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Total number of rows the parsed SQL statement returns |
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Oracle command type definition |
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Mode under which the SQL statement was executed |
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Cost of this query given by the optimizer |
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Optimizer environment |
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Hash value for the optimizer environment |
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User ID of the user who originally built this child cursor |
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Schema ID that was used to originally build this child cursor |
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Schema name that was used to originally build this child cursor |
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Indicates whether this child cursor has been marked to be kept pinned in the cache
using the |
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Address of the handle to the parent for this cursor |
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Descriptor of the type check heap for this child cursor |
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Hash value of the parent statement in the library cache |
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Old SQL hash value |
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Numeric representation of the SQL plan for this cursor. Comparing one
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Number of this child cursor |
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Service name |
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Hash value for the name listed in the
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Contains the name of the module that was executing at the time that the SQL statement
was first parsed, which is set by calling |
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Hash value of the module listed in the
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Contains the name of the action that was executing at the time that the SQL statement
was first parsed, which is set by calling |
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Hash value of the action listed in the
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Number of times the transaction failed to serialize, producing
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If an outline was applied during construction of the cursor, then this column displays the category of that outline. Otherwise the column is left blank. |
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CPU time (in microseconds) used by this cursor for parsing, executing, and fetching |
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一.
先看官網對這幾個檢視的說明（ORACLE 11gR2）
1.1 V$SQL
V$SQL lists statistics
on shared SQL areas without t 三大SQL性能視圖這裏做個筆記，純屬是加深印象：
V$SQL lists statistics on shared SQL areas without the GROUP BY clause and contains one row for each child of the original SQL tex
v$sqltext中有記憶體中完整的sql語句(SQL被分割為多行儲存)，而其他兩個檢視都是部分sql語句。但v$sqltext中儲存的比較簡單，沒有該語句的統計資訊，比如執行次數等。
v$sqltext 的欄位如下： ADDRESS &
select nvl(max(to_number(mingxibh)), 0) as lMaxXuhao from klnl_dkkhmx where dkjiejuh=:1 and farendma=:2 and trim(translate(min
共同點：
1）都儲存了sql內容
2) 記錄的都是位於記憶體中的sql內容
檢視v$sql,v$sqlarea,v$sqltext,v$sqltext_with_newlines 是幾個經常容易混淆的檢視，主要是提供library cache中當前快取的sql語句的資訊。這幾個檢視都可以提供當前有關sql語句的具體資訊，但稍有差異。本文主
今天要驗證一個Full table scan問題的patch，需要分析一下sql執行情況，用到了v$sqlarea檢視，感覺這篇文章講得挺明白，摘抄一部分做個讀書筆記。
1 常用檢視說明
Oracle sql語句資源消耗監控，最常用的系統檢視有：
v$sql
def lte color ech dap wait resolv users select SYS@newtest>DESC V$SQL名稱 是否為空? 類型
SQL_TEXT
如果知道了session的sid就可以找到當前session正在執行的sql：
SQL> select sql_text,fetches,executions,parse_calls,disk_reads,cpu_time,elapsed_time from v$s som 實現 表單 some rdquo 雙向 情況 blank 如果 VUE學習篇1
Mustache (雙大括號寫法)不能在 HTML 屬性中使用，應使用 v-bind 指令：
<div v-bind:id="dynamicId"></div& 循環 求值 因此 一次 -s value compute 結果 事件監聽 方法（method）和計算屬性（computed）區別
每當觸發重新渲染時，調用方法將總會再次執行函數。
計算屬性是基於它們的依賴進行緩存的。計算屬性只有在它的相關依賴發生改變時才會重新求值。多次 V$SQL 優化 SQL語句 詳解v$SQL視圖
查詢消耗磁盤I/O最多的SQL語句
select sql_text,executions,disk_reads
from v$sql
where disk_reads>&number
order by di 一般來說 運行 什麽 事件 例子 基於 表達 過程 bind
1.兩者的區別 v-if vs v-show
v-if 是“真正”的條件渲染，因為它會確保在切換過程中條件塊內的事件監聽器和子組件適當地被銷毀和重建。 v-if 也是惰性的：如果在初始
V$SESSION_EVENT 和 V$SYSTEM_EVENT
V$SESSION 及 V$SESSION_WAIT 檢視記錄了活動會話當前正在發生的等待 ， 但 是 要 知 道 一 個 活 動 會 話 在 其 生 命 周 期 只 能 可 能 經 歷 很 多 等
<template>
<div id="app">
<h1>Hello Vuex</h1>
<p>{{aaa}}</p>
<button @click="ad
同：
在網速慢的情況下，頁面會顯示{{xx}}，然後等到解析完成後，才會改變成相應的資料；
所以使用這三種指令都可以防止插值表示式的閃爍；
[v-clock] {
display:none
}
<p v-cloak>{{msg}}</p> 其中 v-clo
vue預設會把資料當成一個字串進行分析，而不會對其中的dom節點進行分析。採用v-html可以讓vue對dom的節點進行分析，如果要求不對dom節點進行分析的，可以採用v-text，或者什麼也不寫
程式碼如下：
<div id="app">
<p>{{htm
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v-if 是“真正”的條件渲染，因為它會確保在切換過程中條件塊內的事件監聽器和子元件適當地被銷燬和重建。
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