Index

Question

Answer 1

(10)

 for 10,000  records we require 100 blocks as question said only one block should present at a time in a memory with access time of 10 MS than to access the block from memory is should require atleast 980 MSEC because our word is present in 98^th  block so first block access is (10+reamining access of 97 blocks will be 970 MSEC )but those 97 blocks should be replaced from secondary storage to memory and that time should be added to 980 MSEC so i think answer should be 980 MSEC.

(11)

as primary index is built and index block contain 100 enteries ,there are 100 blocks of data file present and each FIRST RECORD(ANCHOR RECORD) should BE MADE AS INDEX ENTRY so NO OF ANCHOR RECORDS ARE 100 (i,e 100 BLOCKS) therefore 100 index entry in primary index

so to search index block need 10 MSEC AND AFTER THAT ACCCESING  OF DATA FILE FURTHER REQUIRES ONE BLOCK ACEESS 

total 2 BLOCK ACCES =20 MSEC.

Comments

once we have accessed the block in main memory which require 10ms don't we need to search for desired anchor record in that block...why this time is not included?

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According to me SUPPOSE when we got first INDEX ENTRY of through PRIMARY INDEX block than that entry WILL POINT TO BLOCK OF DATA FILE WITH THE HELP OF BLOCK POINTER than after that all the susequent records (i.e BELOW the ANCHOR RECORD ) OF DATA FILE MAY need time to search FOR PARTICULAR RECORD (as after ANCHOR RECORD there are 99 records ) using BINARY SEARCH WE can access those 99 records but THAT THING IS NOT ASKED BY THE question.QUESTION SAID THAT IN TOTAL HOW MANY BLOCKS ACCESS?? SO TOTAL OF 2 BLOCKS ACCESS..