Optimiser checks

Advertisement

how does an optimiser knows whether to perform full tablescan or indexscan pls explain me with a example if possible.
thanks
Manasa

Advertisement

It depends on whether you are using the rule based optimizer (RBO) or the cost based optimizer (CBO). If you are using the CBO, it will depend on a wide variety of factors-- index and table statistics, Oracle version, optimizer parameter settings, system statistics, etc.
Assuming you are the CBO, Oracle attempts to determine whether it is more efficient to read X rows by getting X ROWID's from the index and doing X single block reads from the disk or whether it is more efficient to do Y multiblock reads to full-scan the table. If your single block reads are all reads from memory, rather than disk, that biases Oracle toward index scans. If your multiblock reads are significantly more efficient than single block reads, that biases Oracle toward table scans. If Oracle thinks it is going to have to look at almost every row anyway, that biases it toward table scans.
Justin
Distributed Database Consulting, Inc.
http://www.ddbcinc.com/askDDBC

November 30, -0001

Optimiser checks

how does an optimiser knows whether to perform full tablescan or indexscan pls explain me with a example if possible. thanks ManasaIt depends on whether you are using the rule based optimizer (RBO) or the cost based optimizer (CBO). If you are using

Adobe 10 - will it solve V8 optimisation problems

Hi. I currently have Adobe ACROBAT Pro V8. I've always been able to make and optimise pdfs from Word docs and Powerpoint presentations. Then in December last year, I stopped being able to optimise pdfs that had been made from Powerpoint presentations

Optimising replication & Realignment queues (SMOHQUEUE)

Dear Mobile Heroes, In days of old when CRM 2.0 and 3.0 ruled the earth, it was considered good practice to optimise the CRM-R&R queues (before performing an AC-Extract of multiple sites), by putting all queues on hold before extracting, and then the

IPhone Optimised Sites Work on 5800

Posted this on a couple of other sites but thought you guys here might find it interesting! Yup, I did some tests and most iPhone optimised sites work on the 5800, deviantart: iphone.deviantart.com Facebook: iphone.facebook.com ebay: iphone.ebay.com

The time characteristic consistency check has produced an error     DBMAN     62

Hi We are getting an error while updating to one target as The time characteristic consistency check has produced an error"" * Checked the respective PSA data field  which is fine. Dates are in correct format. * RSRV ran for the particular targe

Checking the performance of Pl/SQL Procedure

I have a PL/SQL procedure of 10,000 lines, & I dont have any Tool of performance checking only thing I have is SQL Client & database how whould I check the performance of the procedureWhy do you want to check the performance? Have you indentified

Delta in Write optimised DSO

How delta datas are handled when loading the write optimised, transactional DSO(sice they don't have any change log tables)?Hi, Delta Administration: Data that is loaded into Write-Optimized Data Store objects is available immediately for further pro

SNP Discrete Optimiser getting cancelled.

Hi All, I am trying to run SNP discrete Optimiser, which gets cancelled after completing the run time limit, giving the error message" Error in module Supply Network Optimizer, error id: 600". I tried running it linearly and it completes without

ACTIVATION OF DSO error: write optimise dso -

I have taken two info objects 1. customerid and 1. price created data source and done activation created DSO with WRITE OPTIMISE DSO (ticked the below line also) and after clicking activation, getting error message info object 0request is not availab

Seek for urgent help about checking s/n from explorer file. Thx

Hi, If i want to check the hardware's s/n and i only have a explorer file that generated from that machine. Is it possible to check it from the explorer? If yes, how to check it? Anyone can help me on this urgent matter? Thanks a lot. Best regards Ba

Please check my website

Hi ALL, Who is willing to check my website and post some remarks. I set my Safari with a style sheet 170%, this is hard to see the real size of my website. It looks good in Opera and Fire Fox, but I have doubt in Safari. I only took a 60 days trail a

DBLINK status check or query timeout through it

I am accessing some values through DB links in my triggers.The problem is if the remote db is down , the trigger much time (around 75sec) to give me error 12535, 00000, "TNS:operation timed out". I want to reduce this time , i tried changing in

Reg : Check boxes

Hi Experts , Im Having 3 select-options on my selection screen !! after that im having 3 check boxes.. first checkbox default it wil be selected. Now My query is ?? 1. when i execute default the first check box & process has to be exexute ? 2. pls gi

Using Sound Check...?

Hi, I just wanted to know what the sound quality/what the difference is, if i tick the "Use Sound Check" in the Ipod options, when the Shuffle is connected to the PC.Sound Check does not alter the file. It analyzes the sound level, and saves tha

Text after checking my voicemail

If there a way to turn this off, please tell me. The phone sends me a text after i check my vm.Hello everyone, as Ann stated, the new software for the Rhyme does resolve the issue with the device receiving text messages after checking or receiving vo

Checking filed data in structure

Hi all,       I have been a structure name in which some of the fields i need to pull out and mapthem. but i need to check whether the data is available in those fields or not for the HR. can any one tell me how to check data in a structure. John.hi,

Authority-Check

Hi All.. My requirement is to incorporate the Authority-Check for Sales Organization field ( VBAK-VKORG) inthe selection screen. In the meanwhlie, i should restrict further processing of Report, if unauthorized Sales Organzations. Please help me in e

Using Forms OLE builtin to access word spell check

I am trying to find a way to utilize the Forms OLE built in for using MS Word spell check. We are upgrading our forms from 6 to 10g. In version 6 we were able to use OLE to open word and use it to pass in our string we wanted spell checked. Is there

None of the commnets or other type of annotations on this page are contained in the structure tree, getting this error on full check of adobe acrobat PDF

none of the commnets or other type of annotations on this page are contained in the structure tree, getting this error on full check of adobe acrobat PDFYou can find and tag the unmarked annotations using the Tags pane - click the down arrow next to

Databse connection when an application module is checked out

Hi, I have an application module pool and database connection pool, Documentations suggest that, when an application module is released in stateless mode irrespective of the jbo.doconnectionpooling property the connection aquired by the app module wi