Physical and Logical Structures of DB

Hi all
Why datafiles are called physical structure of database and tablespace,segment etc are called logical structures of database as datafile is also a name given to memory area on disk drive ,therefore it should also be called logical structure

user13345475 wrote:
as datafile is also a name given to memory area on disk driveNo it is not. There are no "+memory areas+" on disk. The closest to that will be a virtual memory page that has been written to disk (e.g. written to a raw swap device or to a swap file).
A physical disk itself does not have "memory areas" on the disk platters. The correct term would be "storage location". Memory areas exist in physical memory instead.
I suggest that you review your understanding of technical terms.

Similar Messages

Separation of the physical and logical structures

Hi,
I am very new to Oracle database administration. While reading Sam Alapati's book "Expert Oracle9i Database Administration," I came across the concept of the separation of an Oracle database’s physical storage structures from its logical storage structures. In particular, Sam states the following in his book:
“This logical defining of Oracle's database structure has another fundamental motive behind it. By organizing space into logical structures and assigning these logical entities to users of the database, Oracle databases achieve the logical separation of users (owners of the database objects, such as tables) of the database from the physical manifestations of the database in terms of data files and so forth.”
I am not quite convinced about the value this separation of the physical and logical really adds to the task of database administration. Considering the way DBASE worked, i.e. each table used to be stored as a separate file, what would be lost if Oracle’s implementation were similar and each table (i.e. file) were to be assigned to a particular user. I am not sure of the value added by storing the data from more than one table in more than one file, effectively resulting in a many-to-many relationship between tables and files. Please enlighten me. I would really appreciate it.
Karim

and each table were to be assigned to a particular user. Don't know what you mean. In Oracle, every table has one and only one owner.
I am not sure of the value added by storing the data from more than one table in more than one fileIf an application has a thousand tables, would you rather manage 1000 files or 1?
In general, separating the physical from the logical allows the physical structure to change without affecting the logical (in theory at least). Even a table is a logical structure. We think of rows and columns, but it isn't stored the way we think of it. When we do a select statement, we don't have to write code to read each block, extract the contents, etc.
With partitioned tables, it is sometimes a good idea to split up partitions in such a way to get a performance gain. Like placing the most recent (and most queried) month of data on the fastest storage device. If you stuffed everything in to one gigantic file, you would lose that ability.
If you want to store each table as a separate file, you can do that with Oracle. For each new table, create a new tablespace, and then create a new file for the tablespace. Then come back to this forum in a year and tell us how it's going.

Query on Physical and Logical structures

Hi All
Please Open the following link that opens a figure a 12-1 Logaical and physical storage . Please explain me how an data file can have many extents ( An arrow between Data file and extent i.e one to many relation ship ) , as the data file stores data in operating system blocks .
[http://download.oracle.com/docs/cd/E11882_01/server.112/e10713/logical.htm#i8531]
Thank you
Aravind

user8709943 wrote:
Hi
can we upload the an image here . if yes , please tell me how to .
Thank youI don't know of any way to upload images, but the url you provided is working for me.
Let me try again.
There is no concept of extents in the datafile at the OS level, at least not that has any bearing at all on oracle or any other application that would access a data file.
A data file is created of some size, let's say 10gb. Remember that even this data file is an OS abstraction of sectors on a disk. If some app (be it Oracle, MS Word, Quicken, whatever) asks the OS to read a file, the OS translates that request to the disk controller, which figures out what sectors (cylinder,track,offset) have to be returned in what order to satisfy the request from the OS.
When Oracle creates a tablespace, or adds a file to a tablespace, it simply asks the OS to create a file of some size. Oracle doesn't know or care how that happens. Oracle doesn't know or care how the OS keeps track of the parts of that file. Oracle doesn't know or care where that file is. Oracle doesn't know or care about OS blocks. All Oracle (or any app) knows is that there exists a file of 10gb. To Oracle, that file is nothing but an address space, beginning at zero and extending for 10gb from there. Whenever Oracle needs data from the file, it will ask the OS for 'x' bytes beginning at offset 'y'. It's up to the OS to figure out what that means. Conversly, the OS doesn't even know about tablespaces. As far as the OS is concerned, the file doesn't even 'belong' to oracle. It just exists, it can be opened/read/written by anyone.
Now it's up to oracle to decide what to do with this file. First, he keeps track of its fully qualified name, its size, and what tablespace he is assigning it to. As part of the tablespace definition, we have a blocksize. This defines how many bytes Oracle will request from the os on any i/o operations. It will be up to the OS to decide what that means.
Next, we create a table. Part of that request will include (explicitly or implicity) an amount of space to reserve in the tablespace. So oracle will create an extent. This simply means that Oracle will make note of the fact that a part of the file beginning with block 'x' and extending for 'y' blocks, will be reserved for exclusive use of that table. Again, these are oracle blocks. The OS neither knows nor cares about any of this.
Now we insert a row into our table. Oracle looks for an available block in the extent reserved for that table, and reads it into the buffer. For this read operation, oracle simply asks the os for <oracle_block_size> bytes, beginning at offset 'x' from data file 'y'. Oracle's own internal bookkeeping is used to determine the value of 'offset x' before the request is passed to the os. Again, the OS knows nothing about any of this (tablespaces, segments, extents, even oracle blocks); all it knows is a request to get a specified number of bytes beginning at a specified offset of a specified file. If it (the os) does that by having a structure it calls an extent and/or a structure it calls a block, fine. But Oracle doesn't know or care about any of that.
As for an oracle block equaling an OS block, or the rule that an oracle block must be an integer multiple of an OS block ... even that is not true. It is best for i/o efficiency if the oracle block is an integer multiple of the os block. But in strict terms, since neither knows or cares about the other, they do not have to be equal.

Export physical and logical details on ASA 5520 and 8.0 software

Hello...does anybody know if there is any way to export details of the physical and logical interface details (including interface descriptions) to Excel, PDF or and other format from the command line or ASDM?
Thanks,
John

Export directly in xls, xlsx or pdf - no.
The output of "show run interface" or "show interface" is pretty structured however and easily parsed by Excel - either manually or via a macro. See output below (you can omit the interface identifier to get all interfaces. I used one for brevity.)
One can build a script to log in, perform an arbitrary command logging the output to a file which can then be massaged to extract the information you want in a suitable format (csv, etc.). Once in Excel it can be saved as pdf if you're so inclined.
Of couse, some of the full-featured network management tools do a lot of this (and lots more) if you have them.
ASA-1# sh run int eth0/0
interface Ethernet0/0
nameif outside
security-level 0
ip address x.x.x.x 255.255.255.224
ASA-1#
ASA-1# sh int eth0/0
Interface Ethernet0/0 "outside", is up, line protocol is up
Hardware is i82546GB rev03, BW 1000 Mbps, DLY 10 usec
Auto-Duplex(Full-duplex), Auto-Speed(1000 Mbps)
Input flow control is unsupported, output flow control is unsupported
MAC address 0013.c480.6b50, MTU 1500
IP address x.x.x.x, subnet mask 255.255.255.224
14156274 packets input, 16095096189 bytes, 0 no buffer
Received 44764 broadcasts, 0 runts, 0 giants
0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored, 0 abort
0 pause input, 0 resume input
0 L2 decode drops
8548524 packets output, 1006461151 bytes, 0 underruns
0 pause output, 0 resume output
0 output errors, 64 collisions, 6 interface resets
95 late collisions, 627 deferred
0 input reset drops, 0 output reset drops, 0 tx hangs
input queue (blocks free curr/low): hardware (255/230)
output queue (blocks free curr/low): hardware (255/125)
Traffic Statistics for "outside":
14156267 packets input, 15839536990 bytes
8548619 packets output, 820243613 bytes
39502 packets dropped
      1 minute input rate 2 pkts/sec, 349 bytes/sec
      1 minute output rate 2 pkts/sec, 425 bytes/sec
      1 minute drop rate, 0 pkts/sec
      5 minute input rate 2 pkts/sec, 2091 bytes/sec
      5 minute output rate 1 pkts/sec, 352 bytes/sec
      5 minute drop rate, 0 pkts/sec

How to collect physical and logical disk counters using query?

Hai friends, i want to view physical and logical disk counters in sql server like Avg. Disk sec/Read, Avg.
Disk Bytes/Read, Avg. Disk sec/Write, Avg.
Disk Bytes/Write, etc., Can anyone tell me how to vies this by using query?
Thanks in advance..

Hai friends, i want to view physical and logical disk counters in sql server like Avg. Disk sec/Read, Avg.
Disk Bytes/Read, Avg. Disk sec/Write, Avg.
Disk Bytes/Write, etc., Can anyone tell me how to vies this by using query?
Thanks in advance..
Hello,
Sys.dm_os_performance counter will only show counters related to SQL server not Physical disk if you run below query in SQL server it will not return any value so no disk counter is present.You will have to see it using perfmon.
select * from sys.dm_os_performance_counters where counter_name like '%disk%'
This can also be done through power shell but I dont have experience with that.You can search net for power shell query to see Windows perfmon counters
Please mark this reply as the answer or vote as helpful, as appropriate, to make it useful for other readers

OBIEE -10.1.3.4.1 - high physical and logical query response

Hi All,
I am facing an performance issue in OBIEE 10g .My report is taking 2 mins to come up and when i fired the physical query in the db the data is coming in 2 secs.
Below is the details from the log file.Here I observed that response time for physical and logical query is 109 sec ~ 2 mins.Please provide me the helpful pointers.
+++Administrator:370000:370015:----2013/01/22 07:28:04
-------------------- Execution Node: <<2650466>>, Close Row Count = 3332, Row Width = 26000 bytes
+++Administrator:370000:370015:----2013/01/22 07:28:04
-------------------- Execution Node: <<2650466>> DbGateway Exchange, Close Row Count = 3332, Row Width = 26000 bytes
+++Administrator:370000:370015:----2013/01/22 07:28:04
-------------------- Execution Node: <<2650466>> DbGateway Exchange, Close Row Count = 3332, Row Width = 26000 bytes
+++Administrator:370000:370015:----2013/01/22 07:28:04
-------------------- Query Status: Successful Completion
+++Administrator:370000:370015:----2013/01/22 07:28:05
-------------------- Rows 3332, bytes 86632000 retrieved from database query id: <<2650466>>
+++Administrator:370000:370015:----2013/01/22 07:28:05
-------------------- Physical query response time 109 (seconds), id <<2650466>>
+++Administrator:370000:370015:----2013/01/22 07:28:05
-------------------- Physical Query Summary Stats: Number of physical queries 1, Cumulative time 109, DB-connect time 0 (seconds)
+++Administrator:370000:370015:----2013/01/22 07:28:05
-------------------- Rows returned to Client 3332
+++Administrator:370000:370015:----2013/01/22 07:28:05
-------------------- Logical Query Summary Stats: Elapsed time 109, Response time 109, Compilation time 0 (seconds)

Did you run the SQL from a client on the OBIEE server or your local machine? Does the Physical SQL on the OBIEE server against the DB run in 2 Seconds and when sent by the OBIEE server it takes 109 seconds?? Is that correct?

Changing ip of physical and logical host

I have a 2 nodes Sun cluster 2.2 working. I have to put it in another lan, so I have to change both Physical and logical host and terminal concentrator and console ip addresses. How can I do?
Thanks

I don't see a reply so I'll take a shot. Just like you have 0-9 for numbers and you can arrange them anyway you want, you still only have 0-9. You have the physical (system block and datafiles) which are somewhat static. Then you have the the logical (tablespace, segements, extents)which are volatile and connected by chaining (links) which may be all over the place in the physical but appears to be one whole unit in the logical. Just like an image on a TV screen wearing a red hat, you see a red hat (logical) but it is actual pixels which are chained or linked (data pointers) to each other by the color red. I hope that helps until someone comes by with a better answer.

Difference between physical and logical standby database

What is the difference between physical and logical standby database?

Hi,
Physical Standy where its a read only DB.
Logs are applied.
Logical Standy where it can be Read / Write DB and the logs are applied in terms of SQL Statements.
Thanks & Regards,
Pavan Kumar N

Oracle - ROWID (Physical and logical)

Hi,
Could you please clarify the below doubts?
- Difference between Physical and Logical ROWID's
- Difference between ROWID and UROWID datatypes
Regards,
Ragav

Instead of an answer, may I suggest you go through following link?
http://download.oracle.com/docs/cd/B19306_01/server.102/b14220/datatype.htm#sthref3894

Physical and Logical path

Hello,
what is a physical file and logical file in PATH table of SAP.
Plz help,
aafaq

Hi aafaqhusain,
1. logical file path is nothing but a    IDENTIFIER/STRING/NAME
= the name by which
   we refer to that file.
(in our programs)
2. The physical location of that file,
   may change from server to server,
or from time to time.
(hence, we do not use hardcoded physical path,
   in our programs,
   but instead use this MAPPING of logical path,
to the physical path)
regards,
amit m.

Manipulations with physical and logical names

Hello ppl,
Is there any way to see/change phisical and logical names of object in one place/screen? I mean I want to set them to different values and see that change, but without fuzzu, complex way of changing naming and propagate modes.
TIA,
Alex

Mark,
Under project, preferences (from the main console) you can set the naming and also the propagation method. That's what I hate to do :) However, thinking deeper I find it ok - first finish with modelling and physical names, than correct logical names as needed without propaation to physical.
Alex

Physical and logical partation of cube

hi
can i get scenerio for logical and physical partation of cube.
based on year or calmonth that is called physical partation? or not
what is logical partation

Hi sunil,
Partitioning is mainly done to increase the performance by optiomizing the Time Utility.
Physical Partitioning is the partitioning done at the database level and to do so, we can partition based on the Time,date so on... In terms of Cube partitioning we usually use 0CALMONTH, 0CALYEAR or 0FISCYEAR.
And
Logical Partitioning is the partitioning done at the Query level while retriving data from the cube. This is said to be Logical because the data is not partitioned at the database level.
Ex: Restict the Query using 0CALMONT,0CALYEAR.
Hope this helps you and solves your problem,if it helps assgn pnts.
Regards
neelima

Physical and Logical Standby

Hi
I just wanted to know can i have one Physical and One Logical Standby for a Single Primary Database. Is there any precautions and steps to be followed .
Thanks

user9366471 wrote:
Hi
I just wanted to know can i have one Physical and One Logical Standby for a Single Primary DatabaseYes this is possible.
See following Oracle 10.2 example which talks also about cascaded standbys:
http://download.oracle.com/docs/cd/B19306_01/server.102/b14239/cascade_appx.htm#i637055

CPU patch procedure with physical and logical standby database in place

Hello All,
I've also placed this in the Upgrades forum, but perhaps this is the best place to have put it.
I'm trying to compile a decent set of steps for applying the CPUOCT2008 patch to our production RAC cluster which has both a logical and physical standby in place. I've read a tonne of documentation, including the CPU readme, DOCID 437276.1 and 278641.1. I''ve also read through the Upgrading Databases in a Data Guard Configuration chapter of Dataguard Concepts and Administration. The last doc mentioned is really for upgrading a full version of Oracle rather than applying a CPU (at least I think that's the case). DocID 437276.1 is rather sparse on details.
I guess what I'm trying to understand is the proper method for applying the patch with the logical standby in place. The physical standby looks pretty straightforward. After running opatch on it as well, it will basically have all of the changes applied to the primary shipped over and applied as per the normal primary/standby relationship. Will the same be true for the logical (having applied the patch, and then re-enabling SQL apply)? Should I aim to have it work that way? By that I mean start it up and re-enable sql apply and then upgrade the primary. Or, am I to apply the catcpu.sql script to it as well before re-enabling the sql apply? Am I wrong in regards to the physical standby as well i.e. should the catcpu also be applied directly to it?
Thanks very much in advance.
Cheers,
Chris
Edited by: chris.baron on Dec 12, 2008 11:38 AM

Given the fact that your system is far from main-stream I'd recommend opening an SR with Oracle Support Services (metalink) and asking them.
If you would like to publish a White Paper on your experience after you have successfully completed the project let me know off-line.

Apply CPUOCT2008 with both a physical and logical standby in place

Hello All,
I'm trying to compile a decent set of steps for applying the CPUOCT2008 patch to our production RAC cluster which has both a logical and physical standby in place. I've read a tonne of documentation, including the CPU readme, DOCID 437276.1 and 278641.1. I''ve also read through the Upgrading Databases in a Data Guard Configuration chapter of Dataguard Concepts and Administration. The last doc mentioned is really for upgrading a full version of Oracle rather than applying a CPU (at least I think that's the case). DocID 437276.1 is rather sparse on details.
I guess what I'm trying to understand is the proper method for applying the patch with the logical standby in place. The physical standby looks pretty straightforward. After running opatch on it as well, it will basically have all of the changes applied to the primary shipped over and applied as per the normal primary/standby relationship. Will the same be true for the logical (having applied the patch, and then re-enabling SQL apply)? Should I aim to have it work that way? By that I mean start it up and re-enable sql apply and then upgrade the primary. Or, am I to apply the catcpu.sql script to it as well before re-enabling the sql apply? Am I wrong in regards to the physical standby as well i.e. should the catcpu also be applied directly to it?
Thanks very much in advance.
Cheers,
Chris

Given the fact that your system is far from main-stream I'd recommend opening an SR with Oracle Support Services (metalink) and asking them.
If you would like to publish a White Paper on your experience after you have successfully completed the project let me know off-line.

Physical and Logical Structures of DB

Similar Messages

Maybe you are looking for