Thanks for the insight Rod. is there any other place i can know more abt these principles?
But if the table is clustered then the pages are stored catagiously with respect to that column rite? > On Fri, 2002-11-01 at 08:03, [EMAIL PROTECTED] wrote: >> >> Hi Rod , >> >> Does it means that index scan is used for less frequenlty occuring data? yes my >table was not >> clustered. >> >> can u tell me what does 0.00..6788.24 and rows and width means? >> >> in explain out put cost=0.00..6788.24 rows=30001 width=4 >> >> >> I have one more table where i face the similar problem , i have not dump - reloaded >it yet , >> will post again if i face the problem. > > Keep in mind that an index scan is very expensive in regards to a single tuple. It >has to run > through (fetch) the index pages, then fetch the pages from the table. Since the >table fetches > are random, the harddrive will probably incur a seek for each tuple found in the >index. The > seeks add up much quicker than a sequential scan (without nearly as many seeks or >drive head > movements). > > -- > Rod Taylor ----------------------------------------- Get your free web based email at trade-india.com. "India's Leading B2B eMarketplace.!" http://www.trade-india.com/ ---------------------------(end of broadcast)--------------------------- TIP 1: subscribe and unsubscribe commands go to [EMAIL PROTECTED]
