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Home -> Community -> Mailing Lists -> Oracle-L -> RE: HIGH WATER MARK
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One tidbit you forgot, Javier: A FTS will scan all the way up to the =
HWM.
Therefore if your application does a lot of full table scans and your =
HWM is
all out of whack, performance can be improved by resetting your HWM.=20
=20
=20
Lisa Rutland Koivu=20
Oracle Database Administrator=20
Qode.com=20
4850 North State Road 7=20
Suite G104=20
Fort Lauderdale, FL 33319=20
V: 954.484.3191, x174=20 F: 954.484.2933=20 C: 954.658.5849=20
"The information contained herein does not express the opinion or =
position
of Qode.com and cannot be attributed to or made binding upon Qode.com."
-----Original Message-----
From: Javier Morales [mailto:Javier_at_infojobs.net]
Sent: Thursday, November 02, 2000 5:21 AM
To: Multiple recipients of list ORACLE-L
Subject: RE: HIGH WATER MARK
The high water mark is the same concept than the water of the dock or =
the
sea-ports...
when water raises up, then you can see in the dock where the top was =
the
wather...
... that's the same with Oracle Blocks...
so, if you use "direct inserts", Oracle needs to manage COMPLETE empty blocks... and that's using the HWM as a reference...
let's take a look at my nice ascii art !! ;-P
|----| |----| |----| |----| |----| |----|
|40% | |0% | |60% | |0% | |0% | |0% |
|used| |Used| |Used| | | | | | |
| | | | | | | | | | | |
|----| |----| |----| |----| |----| |----|
^ =20
| =20
HWM
=20
So, imagine that you delete a table with DELETE FROM... It doesn't =
move
the HWM, so if you delete this way and insert direct, you will find =
that the
table increases size :( ... that's why the best is making full deletes =
with
TRUNCATE TABLE if possible.
Hope this would help! ;-)
---------------------------------------=20Javier Morales - javier_at_infojobs.net=20 Administraci=F3n Bases de Datos Oracle - InfoJobs.net=20 Tel. +34 902 10 60 90 Ext. 2067=20
=20
=20
=20
=20
=20
-----Mensaje original-----
De: Dash, Saroj (CAP,CEF) [ mailto:Saroj.Dash_at_gecapital.com
<mailto:Saroj.Dash_at_gecapital.com> ]
Enviado el: jueves 2 de noviembre de 2000 3:01
Para: Multiple recipients of list ORACLE-L
Asunto: ?: HIGH WATER MARK
Hello Dbas,
What do you mean By High water mark ?? In OEM the rollback segment =
shows the
High water mark.
Please tell me the concept l about that.
Saroj.
-- Please see the official ORACLE-L FAQ: http://www.orafaq.com <http://www.orafaq.com>=20 -- Author: Dash, Saroj (CAP,CEF) INET: Saroj.Dash_at_gecapital.com Fat City Network Services -- (858) 538-5051 FAX: (858) 538-5051 San Diego, California -- Public Internet access / Mailing Lists -------------------------------------------------------------------- To REMOVE yourself from this mailing list, send an E-Mail message to: ListGuru_at_fatcity.com (note EXACT spelling of 'ListGuru') and in the message BODY, include a line containing: UNSUB ORACLE-L (or the name of mailing list you want to be removed from). You may also send the HELP command for other information (like subscribing). ------_=_NextPart_001_01C044D0.1EB75D96 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN"> <HTML><HEAD> <META HTTP-EQUIV=3D"Content-Type" CONTENT=3D"text/html; = charset=3Diso-8859-1"> <TITLE></TITLE> <META content=3D"MSHTML 5.00.3103.1000" name=3DGENERATOR></HEAD> <BODY> <DIV><FONT color=3D#0000ff face=3DArial size=3D2><SPAN = class=3D987382213-02112000>One=20 tidbit you forgot, Javier: A FTS will scan all the way up to the=20 HWM. Therefore if your application does a lot of full table scans = and your=20 HWM is all out of whack, performance can be improved by resetting your = HWM.=20 </SPAN></FONT></DIV> <DIV> </DIV> <DIV> </DIV> <P><B><FONT face=3DArial size=3D1>Lisa Rutland Koivu</FONT></B> = <BR><FONT face=3DArial=20 size=3D1>Oracle Database Administrator</FONT> <BR><FONT face=3DArial=20 size=3D1>Qode.com</FONT> <BR><FONT face=3DArial size=3D1>4850 North = State Road=20 7</FONT> <BR><FONT face=3DArial size=3D1>Suite G104</FONT> <BR><FONT = face=3DArial=20 size=3D1>Fort Lauderdale, FL 33319</FONT> </P> <P><FONT face=3DArial size=3D1>V: 954.484.3191, x174</FONT> <BR><FONT = face=3DArial=20 size=3D1>F: 954.484.2933 </FONT><BR><FONT face=3DArial size=3D1>C: = 954.658.5849</FONT>=20 <BR><FONT face=3DArial size=3D1><A href=3D"http://www.qode.com/"=20 target=3D_blank>http://www.qode.com</A></FONT> </P> <P><I><FONT color=3D#000000 face=3DArial size=3D1>"The information = contained herein=20 does not express the opinion or position of Qode.com and cannot be = attributed to=20 or made binding upon Qode.com."</FONT></I></P> <BLOCKQUOTE style=3D"MARGIN-RIGHT: 0px"> <DIV align=3Dleft class=3DOutlookMessageHeader dir=3Dltr><FONT = face=3DTahoma=20 size=3D2>-----Original Message-----<BR><B>From:</B> Javier Morales=20 [mailto:Javier_at_infojobs.net]<BR><B>Sent:</B> Thursday, November 02, = 2000 5:21=20 AM<BR><B>To:</B> Multiple recipients of list = ORACLE-L<BR><B>Subject:</B> RE:=20 HIGH WATER MARK<BR><BR></DIV></FONT> <P><FONT size=3D2><FONT face=3DVerdana>The high water mark is the = same concept=20 than the water of the dock or the sea-ports...<BR><BR>when water = raises up,=20 then you can see in the dock where the top was the wather...<BR>... = that's the=20 same with Oracle Blocks...<BR><BR><BR>so, if you use "direct = inserts", Oracle=20 needs to manage COMPLETE empty blocks... and that's using the HWM as = a=20 reference...<BR><BR>let's take a look at my nice ascii art !! =20 ;-P<BR><BR></FONT><FONT face=3DCourier><FONT = face=3DCourier>|----| =20 |----| |----| |----| |----| |----|<BR>|40% | = |0% =20 | |60% | |0% | |0% | |0% |<FONT=20 face=3DCourier><BR>|used| |Used| |Used| = | |=20 | | | |<FONT=20 face=3DCourier><BR>| | | =20 | | | | | | = | =20 | |<FONT face=3DCourier><BR><FONT = face=3DCourier>|----| =20 |----| |----| |----| |----| |----|<FONT=20 face=3DCourier><BR><FONT=20 = face=3DCourier> &nb= sp; &nb= sp;=20 = ^  = ; =20 <FONT face=3DCourier><BR><FONT=20 = face=3DCourier> &nb= sp; =20 = |  = ;  = ; =20 <FONT face=3DCourier><BR><FONT=20 = face=3DCourier> &nb= sp; =20 =20 = HWM</FONT></FONT></FONT></FONT></FONT></FONT></FONT></FONT></FONT></FONT= ></FONT></FONT></FONT></P> <P><FONT size=3D2><FONT face=3DCourier><FONT face=3DCourier><FONT = face=3DCourier><FONT=20 face=3DCourier><FONT face=3DCourier><FONT face=3DCourier><FONT = face=3DCourier><FONT=20 face=3DCourier><FONT face=3DCourier><FONT face=3DCourier><FONT = face=3DCourier><FONT=20 = face=3DCourier> &nb= sp; <FONT=20 face=3DCourier><BR><FONT face=3DCourier>Oracle wouldn't write in the = 2ond block=20 for a direct insert or a data loading with SQL*Loader, that's because = Oracle=20 needs to know exactly that the blocks are complete=20 = free.</FONT></FONT></FONT></FONT></FONT></FONT></FONT></FONT></FONT></FO= NT></FONT></FONT></FONT></FONT></FONT></P> <P><FONT face=3DVerdana size=3D2>So, imagine that you delete a table=20 with DELETE FROM... It doesn't move the HWM, = so if you=20 delete this way and insert direct, you will find that the table = increases size=20 :( ... that's why the best is making full deletes with TRUNCATE = TABLE if=20 possible.</FONT></P> <P><FONT face=3DVerdana size=3D2>Hope this would help! = ;-)</FONT></P> <P><FONT face=3DVerdana=20 size=3D2> ---------------------------------------</FONT> = <BR><FONT=20 face=3DVerdana size=3D2> Javier Morales - = javier_at_infojobs.net</FONT>=20 <BR><FONT face=3DVerdana size=3D2> Administraci=F3n Bases de = Datos Oracle -=20 InfoJobs.net</FONT> <BR><FONT face=3DVerdana size=3D2> Tel. = +34 </FONT>=20 <FONT face=3DVerdana size=3D2>902 10 60 90</FONT><FONT face=3DVerdana = size=3D2> =20 Ext. 2067</FONT> <BR><FONT face=3DVerdana size=3D2> Fax. +34 = (93) 580 56=20 60</FONT> <BR><FONT face=3DVerdana size=3D2> </FONT> </P> <P><BR> </P> <P> </P> <P> </P> <P> </P> <P> </P> <P><FONT size=3D2>-----Mensaje original-----<BR>De: Dash, Saroj = (CAP,CEF) [<A=20 = href=3D"mailto:Saroj.Dash_at_gecapital.com">mailto:Saroj.Dash_at_gecapital.com= </A>]<BR>Enviado=20 el: jueves 2 de noviembre de 2000 3:01<BR>Para: Multiple recipients = of list=20 ORACLE-L<BR>Asunto: ?: HIGH WATER MARK<BR><BR><BR>Hello = Dbas,<BR><BR>What do=20 you mean By High water mark ?? In OEM the rollback segment shows = the<BR>High=20 water mark.<BR><BR>Please tell me the concept l about=20 that.<BR><BR>Saroj.<BR><BR>--<BR>Please see the official ORACLE-L = FAQ: <A=20 href=3D"http://www.orafaq.com"=20 target=3D_blank>http://www.orafaq.com</A><BR>--<BR>Author: Dash, = Saroj =20 (CAP,CEF)<BR> INET: Saroj.Dash_at_gecapital.com<BR><BR>Fat City = Network=20 Services -- (858) 538-5051 FAX: (858) = 538-5051<BR>San=20 Diego, California -- Public = Internet=20 access / Mailing=20 = Lists<BR>---------------------------------------------------------------= -----<BR>To=20 REMOVE yourself from this mailing list, send an E-Mail message<BR>to: = ListGuru_at_fatcity.com (note EXACT spelling of 'ListGuru') and = in<BR>the message=20Received on Thu Nov 02 2000 - 07:23:42 CST
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