Monday, March 26, 2012

Fill factor for ever increasing clustered index

Alan
Fillfactoe specifies how full each page should be. 70 means 70%
full, 100 means 100% full. The only special case is 0, which means the leaf
level is full, but there is room for one or two rows per page in the upper
levels of the index tree.
"Alan T" <alanNOSPAMpltse@.yahoo.com.au> wrote in message
news:OYuLvsMWIHA.2268@.TK2MSFTNGP02.phx.gbl...
> If I defined the clustered index on identity column, what will be the
> differences between fill factor 100% and 70%?
>
Most people forget about this scenario when choosing to go with 100% fill
factors.
Kevin G. Boles
Indicium Resources, Inc.
SQL Server MVP
kgboles a earthlink dt net
"Greg Linwood" <g_linwood@.hotmail.com> wrote in message
news:e6taOTOWIHA.3400@.TK2MSFTNGP03.phx.gbl...
> Except where rows are updated with wider values so they no longer fit on
> their pages.
> A very common example is "notes" type columns which are very often
> widened, causing page splits even on ID based CIXs.
> For these scenarios, you might still want to leave some fillfactor space
> otherwise your updates might be slowed down badly
> Regards,
> Greg Linwood
> SQL Server MVP
> http://blogs.sqlserver.org.au/blogs/greg_linwood
> Benchmark your query performance
> http://www.SQLBenchmarkPro.com
> "Tibor Karaszi" <tibor_please.no.email_karaszi@.hotmail.nomail.com> wrote
> in message news:ECBF8708-C3A0-4BAE-8138-ED856A3C598A@.microsoft.com...
>
|||Yes, so this is most of the answer to the OP. I believe he was wondering on
an increasing value if there was any reason to go with 70 vs 100. The answer
has to do with what else are you going to do with the table besides INSERTs.
HTH
Kalen Delaney, SQL Server MVP
www.InsideSQLServer.com
http://blog.kalendelaney.com
"TheSQLGuru" <kgboles@.earthlink.net> wrote in message
news:13ovperrb5uhvd1@.corp.supernews.com...
> Most people forget about this scenario when choosing to go with 100% fill
> factors.
> --
> Kevin G. Boles
> Indicium Resources, Inc.
> SQL Server MVP
> kgboles a earthlink dt net
>
> "Greg Linwood" <g_linwood@.hotmail.com> wrote in message
> news:e6taOTOWIHA.3400@.TK2MSFTNGP03.phx.gbl...
>
|||1) it is my understanding that new pages will take the fill factor.
2) Deletes will leave holes in their respective pages. Those holes will be
'filled' when you reindex/defrag.
3) That is my understanding as well.
Kevin G. Boles
Indicium Resources, Inc.
SQL Server MVP
kgboles a earthlink dt net
"Alan T" <alanNOSPAMpltse@.yahoo.com.au> wrote in message
news:O3Dia6YWIHA.4532@.TK2MSFTNGP02.phx.gbl...
> Yes, if for the case of INSERT only, when the last page is full, any
> further
> INSERT will be put into the new page. So there is no difference between
> 10%,
> 20% or 70% or even 100%?
> If there is DELETE, so there will be some holes in the page? Because the
> column is ever increasing. The holes will never be filled unless
> re-indexing? If re-indexing, then this is my original question, does the
> fill factor affect it?
> In my understanding is when the page is splitted, the new page will be
> filled by determined by fill factor.
>
> "Kalen Delaney" <replies@.public_newsgroups.com> wrote in message
> news:OVk%23OSWWIHA.3940@.TK2MSFTNGP05.phx.gbl...
> on
> answer
> INSERTs.
> fill
> on
> space
> the
>
|||No a fill factor is ONLY adhered to during a create or rebuilding of an
index. It would be pointless to always keep a page 70% full for example as
you are inserting new rows. If a page splits approximately half of the rows
stay on the existing page and half on the new page.
Andrew J. Kelly SQL MVP
Solid Quality Mentors
"TheSQLGuru" <kgboles@.earthlink.net> wrote in message
news:13p1m1aqmcpbr15@.corp.supernews.com...
> 1) it is my understanding that new pages will take the fill factor.
> 2) Deletes will leave holes in their respective pages. Those holes will
> be 'filled' when you reindex/defrag.
> 3) That is my understanding as well.
>
> --
> Kevin G. Boles
> Indicium Resources, Inc.
> SQL Server MVP
> kgboles a earthlink dt net
>
> "Alan T" <alanNOSPAMpltse@.yahoo.com.au> wrote in message
> news:O3Dia6YWIHA.4532@.TK2MSFTNGP02.phx.gbl...
>
|||DUH!! You know, having a 2 1/2 year old really does occassionally affect
the adult brain. :-))
Kevin G. Boles
Indicium Resources, Inc.
SQL Server MVP
kgboles a earthlink dt net
"Andrew J. Kelly" <sqlmvpnooospam@.shadhawk.com> wrote in message
news:%23$MU2QfWIHA.4440@.TK2MSFTNGP06.phx.gbl...
> No a fill factor is ONLY adhered to during a create or rebuilding of an
> index. It would be pointless to always keep a page 70% full for example as
> you are inserting new rows. If a page splits approximately half of the
> rows stay on the existing page and half on the new page.
> --
> Andrew J. Kelly SQL MVP
> Solid Quality Mentors
>
> "TheSQLGuru" <kgboles@.earthlink.net> wrote in message
> news:13p1m1aqmcpbr15@.corp.supernews.com...
>
|||Well that isn't really a split then. That's business as usual.
Andrew J. Kelly SQL MVP
Solid Quality Mentors
"Tibor Karaszi" <tibor_please.no.email_karaszi@.hotmail.nomail.com> wrote in
message news:0866CD0D-F637-41D0-8AB3-BB29507196DD@.microsoft.com...
> ... unless the page splits at the "end" (the last row according to the
> index). Then now pages are moves, instead just a new page is linked into
> the linked list, at the end.
> --
> Tibor Karaszi, SQL Server MVP
> http://www.karaszi.com/sqlserver/default.asp
> http://sqlblog.com/blogs/tibor_karaszi
>
> "Andrew J. Kelly" <sqlmvpnooospam@.shadhawk.com> wrote in message
> news:%23$MU2QfWIHA.4440@.TK2MSFTNGP06.phx.gbl...
>
|||I believe it is recorded as a split event. There are also other special
cases where the split will not always be 50/50. I wrote a series of articles
for SQL Magazine about this.
HTH
Kalen Delaney, SQL Server MVP
www.InsideSQLServer.com
http://blog.kalendelaney.com
"Andrew J. Kelly" <sqlmvpnooospam@.shadhawk.com> wrote in message
news:OMTFnWqWIHA.5596@.TK2MSFTNGP05.phx.gbl...
> Well that isn't really a split then. That's business as usual.
> --
> Andrew J. Kelly SQL MVP
> Solid Quality Mentors
>
> "Tibor Karaszi" <tibor_please.no.email_karaszi@.hotmail.nomail.com> wrote
> in message news:0866CD0D-F637-41D0-8AB3-BB29507196DD@.microsoft.com...
>

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