howeverchained hash tables inherit the disadvantages of linked lists firstto store key valuethe space overhead of the next pointer in each entry can be significant secondtraversing linked list has poor cache performancemaking the processor cache ineffective bucket hashing in closed hashingall the records are directly stored in the hash table each record with key value is stored in location called its home position the home position is calculated by applying some hash function in case the home position of the record with key is already occupied by another record then the record will be stored in some other location in the hash table this other location will be determined by the technique that is used for resolving collisions once the records are insertedthe same algorithm is again applied to search for specific record one implementation of closed hashing groups the hash table into buckets where slots of the hash table are divided into buckets thereforeeach bucket contains / slots now when new record has to be insertedthe hash function computes the home position if the slot is freethe record is inserted otherwisethe bucket' slots are sequentially searched until an open slot is found in casethe entire bucket is fullthe record is inserted into an overflow bucket the overflow bucket has infinite capacity at the end of the table and is shared by all the buckets an efficient implementation of bucket hashing will be to use hash function that evenly distributes the records amongst the buckets so that very few records have to be inserted in the overflow bucket when searching recordfirst the hash function is used to determine the bucket in which the record can be present then the bucket is sequentially searched to find the desired record if the record is not found and the bucket still has some empty slotsthen it means that the search is complete and the desired record is not present in the hash table howeverif the bucket is full and the record has not been foundthen the overflow bucket is searched until the record is found or all the records in the overflow bucket have been checked obviouslysearching the overflow bucket can be expensive if it has too many records pros and cons of hashing one advantage of hashing is that no extra space is required to store the index as in the case of other data structures in additiona hash table provides fast data access and an added advantage of rapid updates on the other handthe primary drawback of using the hashing technique for inserting and retrieving data values is that it usually lacks locality and sequential retrieval by key this makes insertion and retrieval of data values even more random all the morechoosing an effective hash function is more of an art than science it is not uncommon (in open-addressed hash tablesto create poor hash function applications of hashing hash tables are widely used in situations where enormous amounts of data have to be accessed to quickly search and retrieve information few typical examples where hashing is used are given here hashing is used for database indexing some database management systems store separate file known as the index file when data has to be retrieved from filethe key information is first searched in the appropriate index file which references the exact record location of the data in the database file this key information in the index file is often stored as hashed value in many database systemsfile and directory hashing is used in high-performance file systems such systems use two complementary techniques to improve the performance of file access while