Message-Id: <10668.120952@fatcity.com> From: "Koivu, Lisa" Date: Thu, 2 Nov 2000 08:23:42 -0500 Subject: RE: HIGH WATER MARK This message is in MIME format. Since your mail reader does not understand this format, some or all of this message may not be legible. ------_=_NextPart_001_01C044D0.1EB75D96 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable 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 http://www.qode.com =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@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 Oracle wouldn't write in the 2ond block for a direct insert or a data loading with SQL*Loader, that's because Oracle needs to know exactly = that the blocks are complete free. 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! ;-) ---------------------------------------=20 Javier Morales - javier@infojobs.net=20 Administraci=F3n Bases de Datos Oracle - InfoJobs.net=20 Tel. +34 902 10 60 90 Ext. 2067=20 Fax. +34 (93) 580 56 60=20 =20 =20 =20 =20 =20 =20 -----Mensaje original----- De: Dash, Saroj (CAP,CEF) [ mailto:Saroj.Dash@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 =20 -- Author: Dash, Saroj (CAP,CEF) INET: Saroj.Dash@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@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

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

Lisa Rutland Koivu =
Oracle Database Administrator
Qode.com
4850 North = State Road=20 7
Suite G104
Fort Lauderdale, FL 33319

V: 954.484.3191, x174
F: 954.484.2933
C: = 954.658.5849=20
http://www.qode.com

"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."

-----Original Message-----
From: Javier Morales=20 [mailto:Javier@infojobs.net]
Sent: Thursday, November 02, = 2000 5:21=20 AM
To: Multiple recipients of list = ORACLE-L
Subject: RE:=20 HIGH WATER MARK

The high water mark is the = same concept=20 than the water of the dock or the sea-ports...

when water = raises up,=20 then you can see in the dock where the top was the wather...
... = that's the=20 same with Oracle Blocks...

so, if you use "direct = inserts", Oracle=20 needs to manage COMPLETE empty blocks... and that's using the HWM as = a=20 reference...

let's take a look at my nice ascii art !! =20 ;-P

|----| =20 |----| |----| |----| |----| |----|
|40% | = |0% =20 |  |60% | |0% | |0% | |0% |
|used| |Used|  |Used| = | |=20 | | |   |
|    | | =20 |  | | |    | | = | =20 | |
|----| =20 |----| |----| |----| |----| |----|
         &nb= sp;           &nb= sp;=20 = ^            = ;   =20
         &nb= sp;     =20 =        |     = ;            = ; =20
         &nb= sp;         =20 =20 = HWM

         &nb= sp;
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.

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.

Hope this would help! = ;-)

--------------------------------------- =
Javier Morales - = javier@infojobs.net=20
Administraci=F3n Bases de = Datos Oracle -=20 InfoJobs.net
Tel. = +34 =20 902 10 60 90 =20 Ext. 2067
Fax. +34 = (93) 580 56=20 60

-----Mensaje original-----
De: Dash, Saroj = (CAP,CEF) [mailto:Saroj.Dash@gecapital.com= ]
Enviado=20 el: jueves 2 de noviembre de 2000 3:01
Para: Multiple recipients = of list=20 ORACLE-L
Asunto: ?: HIGH WATER MARK

Hello = Dbas,

What do=20 you mean By High water mark ?? In OEM the rollback segment shows = the
High=20 water mark.

Please tell me the concept l about=20 that.

Saroj.

--
Please see the official ORACLE-L = FAQ: http://www.orafaq.com
--
Author: Dash, = Saroj =20 (CAP,CEF)
INET: Saroj.Dash@gecapital.com

Fat City = Network=20 Services    -- (858) 538-5051 FAX: (858) = 538-5051
San=20 Diego, California        -- Public = Internet=20 access / Mailing=20 = Lists
---------------------------------------------------------------= -----
To=20 REMOVE yourself from this mailing list, send an E-Mail message
to: = ListGuru@fatcity.com (note EXACT spelling of 'ListGuru') and = in
the message=20