oracle TRIM RTRIM LTRIM 性能
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TRIM RTRIM LTRIM Performance
提问by Pratik
I am only required to do RTRIM()in some part of query but if i do TRIM() will that affect performance.
我只需要RTRIM()在查询的某些部分做，但如果我做 TRIM() 会影响性能。
Is Trim()Slower/Faster/Exactly same(NOT even has negligible difference)
compared to RTRIM()AND LTRIM()?
Trim()与RTRIM()AND相比是否更慢/更快/完全相同（甚至没有可以忽略的差异）LTRIM()？
This is with respect to Oracle 10g ONLY.
这仅适用于 Oracle 10g。
But in case of SQL Server 2005,
Do we have function / method 'x()' such that it can replace RTRIM(LTRIM(' blah.. blah.. '))to a single function ?
但是在 SQL Server 2005 的情况下，我们是否有函数/方法 'x()' 以便它可以替换RTRIM(LTRIM(' blah.. blah.. '))为单个函数？
I simply mean of having "single" function for doing the same functionality what both RTRIM()AND LTRIM()does.
我只是想拥有“单一”功能来执行与RTRIM()AND相同的功能LTRIM()。
采纳答案by Jeffrey Kemp
Based on this rough test there is a small difference:
基于这个粗略的测试，有一个小的区别：
DECLARE
n PLS_INTEGER := DBMS_UTILITY.get_time;
s1 VARCHAR2(32767);
s2 VARCHAR2(32767);
BEGIN
s1 := LPAD('X',15000,' ') || RPAD('X',15000,' ');
FOR i IN 1..1000000 LOOP
NULL;
END LOOP;
DBMS_OUTPUT.put_line('Baseline: ' || (DBMS_UTILITY.get_time - n));
n := DBMS_UTILITY.get_time;
FOR i IN 1..1000000 LOOP
s2 := LTRIM(s1);
END LOOP;
DBMS_OUTPUT.put_line('LTRIM: ' || (DBMS_UTILITY.get_time - n));
n := DBMS_UTILITY.get_time;
FOR i IN 1..1000000 LOOP
s2 := RTRIM(s1);
END LOOP;
DBMS_OUTPUT.put_line('RTRIM: ' || (DBMS_UTILITY.get_time - n));
n := DBMS_UTILITY.get_time;
FOR i IN 1..1000000 LOOP
s2 := TRIM(s1);
END LOOP;
DBMS_OUTPUT.put_line('TRIM: ' || (DBMS_UTILITY.get_time - n));
END;
The difference amounts to up to 0.000128 hundredth's of a second in the worst case:
在最坏的情况下，差异高达 0.000128 百分之一秒：
Baseline: 0
LTRIM: 113
RTRIM: 103
TRIM: 8
Baseline: 0
LTRIM: 136
RTRIM: 133
TRIM: 8
回答by Jeffrey Kemp
The difference in performance will generally be undetectable, especially if it's within a query that gets its data from a table. Choose whichever fits your requirements.
性能差异通常是无法检测到的，尤其是在从表中获取数据的查询中。选择适合您的要求。
回答by Ed Harper
The question is irrelevant for SQL Server, since it implements LTRIMand RTRIMbut not TRIM.
这个问题与 SQL Server 无关，因为它实现了LTRIMandRTRIM但不是TRIM.
See the list of SQL 2005 string functions.
请参阅SQL 2005 字符串函数列表。
回答by Saif Khan
I've never seen anything like a benchmark on the Trims in SQL Server. I've used it a lot and do find some minor performance when dealing with lots of data...minor performance.
我从来没有见过像 SQL Server 中的 Trims 的基准测试。我已经使用了很多，并且在处理大量数据时确实发现了一些次要性能......次要性能。
