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From:Claudio Nanni Date:May 7 2012 9:01am
Subject:Re: 回复: Why is creating indexes faster after i
nserting massive data rows?
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Creating the index in one time is one macro-sort operation,
updating the index at every row is doing the operation on and on again.
If you do not understand the difference I recommend you to read some basics
about sorting algorithms,
very interesting read anyway.

Claudio

2012/5/7 Zhangzhigang <zzgang_2008@stripped>

> johan ....
> >Plain and simple: the indices get updated after every insert statement,
> whereas if you only create the index *after* the inserts, the index gets
> created in a single operation, which is a lot more efficient..
>
>
> Ok, Creating the index *after* the inserts, the index gets created in a
> single operation.
> But the indexes has to be updating row by row after the data rows has all
> been inserted. Does it work in this way?
> So i can not find the different overhead  about two ways.
>
>
>
>
>
> ________________________________
>  发件人: Johan De Meersman <vegivamp@stripped>
> 收件人: Zhangzhigang <zzgang_2008@stripped>
> 抄送: mysql@stripped
> 发送日期: 2012年5月7日, 星期一, 下午 4:28
> 主题: Re: Why is creating indexes faster after inserting massive data rows?
>
> ----- Original Message -----
> > From: "Zhangzhigang" <zzgang_2008@stripped>
> >
> > Creating indexes after inserting massive data rows is faster than
> > before inserting data rows.
> > Please tell me why.
>
> Plain and simple: the indices get updated after every insert statement,
> whereas if you only create the index *after* the inserts, the index gets
> created in a single operation, which is a lot more efficient.
>
> I seem to recall that inside of a transaction (thus, InnoDB or so) the
> difference is markedly less; I might be wrong, though.
>
>
> --
> Bier met grenadyn
> Is als mosterd by den wyn
> Sy die't drinkt, is eene kwezel
> Hy die't drinkt, is ras een ezel
>



-- 
Claudio

Thread
Why is creating indexes faster after inserting massive data rows?Zhangzhigang7 May
  • Re: Why is creating indexes faster after inserting massive data rows?Ananda Kumar7 May
    • 回复: Why is creating indexes faster after inserting massive data rows?Zhangzhigang7 May
  • Re: Why is creating indexes faster after inserting massive data rows?Johan De Meersman7 May
    • 回复: Why is creating indexes faster after inserting massive data rows?Zhangzhigang7 May
      • Re: 回复: Why is creating indexes faster after inserting massive data rows?Alex Schaft7 May
        • 回复: 回复: Why is creating indexes faster after inserting massive data rows?Zhangzhigang7 May
          • Re: 回复: 回复: Why is creating indexes faster after inserting massive data rows?Claudio Nanni7 May
            • too nice not to share it!hsv2 Oct
          • Re: 回复: 回复: Why is creating indexes faster after inserting massive data rows?Mihamina Rakotomandimby30 May
      • Re: 回复: Why is creating indexes faster after inserting massive data rows?Claudio Nanni7 May
        • 回复: 回复: Why is creating indexes faster after inserting massive data rows?Zhangzhigang7 May
      • Re: 回复: Why is creating indexes faster after inserting massive data rows?Johan De Meersman7 May
        • RE: 回复: Why is creating indexes faster after inserting massive data rows?Rick James7 May
        • Re: 回复: Why is creating indexes faster after inserting massive data rows?Karen Abgarian7 May
          • 回复: 回复: Why is creating indexes faster after inserting massive data rows?Zhangzhigang8 May
            • Re: 回复: 回复: Why is creating indexes faster after inserting massive data rows?Karen Abgarian8 May
              • 回复: 回复: 回复: Why is creating indexes faster after inserting massive data rows?Zhangzhigang8 May
                • Re: 回复: 回复: 回复: Why is creating indexes faster after inserting massive data rows?Johan De Meersman8 May
                  • 回复: 回复: 回复: 回复: Why is creating indexes faster after inserting massive data rows?Zhangzhigang8 May
                  • Re: 回复: 回复: 回复: Why is creating indexes faster after inserting massive data rows?Karen Abgarian8 May
                    • 回复: 回复: 回复: 回复: Why is creating indexes faster after inserting massive data rows?Zhangzhigang9 May
              • RE: 回复: 回复: Why is creating indexes faster after inserting massive data rows?Rick James10 May
            • Re: 回复: 回复: Why is creating indexes faster after inserting massive data rows?Johan De Meersman8 May
        • Re: 回复: Why is creating indexes faster after inserting massive data rows?Karen Abgarian7 May
    • RE: Why is creating indexes faster after inserting massive datarows?Rick James7 May
      • 回复: Why is creating indexes faster after inserting massive data rows?Zhangzhigang9 May
        • RE: 回复: Why is creating indexes faster after inserting massive data rows?Rick James9 May
          • Re: 回复: Why is creating indexes faster after inserting massive data rows?Claudio Nanni9 May
          • 回复: 回复: Why is creating indexes faster after inserting massive data rows?Zhangzhigang10 May