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Home -> Community -> Mailing Lists -> Oracle-L -> Re: LMT Migration
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Hi!
Make sure your extents are in size or multiples of your = block_size*db_file_multiblock_read_count. This might help in performance = when doing index fast full scans. Also, if you use striped disks, you = might want to match it with stripe width. But number of extents doesn't cause any performance problems, it = actually never did *for normal operations* where not much extent = allocation or deallocation was done. I personally prefer keeping number = of extents per segment less than 100, but don't get nervous when the = number is 1000 either.
About separating, if you got big application, you could make 4 = tablespaces, a big and small extent one for both applications. = Separating applications only gives you some benefit from administrative = point of view, you can have different backup&recovery strategies for = different applications.. but in small to medium databases, this is not = much of an issue either.
Just a note, if you don't want to move your indexes online, then use = rebuild command with tablespace (and nologging) clause, don't drop & = recreate, rebuild will be faster & generates less IO that way.
Tanel.
At present we have one tablespace containign all indexes . Some = indexes are big in size some are small . Currently tablespace is dict = managed. This tablespace currently highly fragmented . Now I am planning to move the indexes to a LMT. Now how to decide what = should be the extent size for uniform extents ?=20 What is better approach to divide indexs=20 A ) should I devide them that based on size ( big, small ) and create = seperate tablespaces with different values for extent size .=20 b) or seperate them based on modules sooo that accounting and = manufactring related indexes goes to different tablespace.
Does number of extents is a performance issue in LMT as well ? Any = experience ?
Thanks,
-ak
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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN"> <HTML><HEAD> <META http-equiv=3DContent-Type content=3D"text/html; =charset=3Diso-8859-1">
<META content=3D"MSHTML 6.00.2800.1141" name=3DGENERATOR> <STYLE></STYLE> </HEAD> <BODY bgColor=3D#ffffff> <DIV><FONT face=3DArial size=3D2>Hi!</FONT></DIV> <DIV><FONT face=3DArial size=3D2></FONT> </DIV> <DIV><FONT face=3DArial size=3D2>Make sure your extents are in size or =multiples of=20
<DIV><FONT face=3DArial size=3D2></FONT> </DIV> <DIV><FONT face=3DArial size=3D2>Tanel.</FONT></DIV> <BLOCKQUOTE dir=3Dltr=20
PM</DIV>
</FONT></DIV>
<DIV><FONT face=3DArial size=3D2>What is better approach to divide=20
indexs </FONT></DIV>
<DIV><FONT face=3DArial size=3D2>A ) </FONT><FONT face=3DArial =
size=3D2> should I=20
devide them that based on size ( big, small ) and create seperate =
tablespaces=20
with different values for extent size . </FONT></DIV>
<DIV><FONT face=3DArial size=3D2>b) or seperate =
them based=20
on modules sooo that accounting and manufactring related indexes goes =
to=20
different tablespace.</FONT></DIV>
<DIV><FONT face=3DArial size=3D2></FONT> </DIV>
<DIV><FONT face=3DArial size=3D2>Does number of extents is a =
performance issue in=20
LMT as well ? Any experience ?</FONT></DIV>
<DIV><FONT face=3DArial size=3D2></FONT> </DIV>
<DIV><FONT face=3DArial size=3D2>Thanks,</FONT></DIV>
<DIV><FONT face=3DArial size=3D2>-ak</FONT></DIV>
Received on Tue Jul 22 2003 - 11:46:56 CDT
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