Tài liệu Database Systems: The Complete Book- P11 ppt

... tions, and all the changes to the database system that these actions perform will remain in the database. Example 19.24 : The paths in the graph of Fig. 19.18 that lead to the Abort node ... to the transactions at the nodes of the saga. Their job is to roll back the effect of a committed action in a way that does not depend on what has happened to the databa...

Ngày tải lên: 26/01/2014, 15:20

Ngày tải lên: 24/12/2013, 12:17

... happens if there is a failure after line (14); perhaps the computer fails or the network connecting the database to the processor that is actually performing the transfer fails. Then the database ... seat and books it. The other customer's in- vocation then begins and sees that the seat is already occupied. It may matter to the customers who gets the seat, bu...

Ngày tải lên: 21/01/2014, 18:20

... as possible, yet they must, between them, cover all the data regions of the original leaf. Having split the leaf, we replace the region and pointer for the original leaf at the node above by ... the record. If there is no reason to organize the file any other way, we can even use the record number as the search key for a primary index, as discussed in Sec- tion 1...

Ngày tải lên: 21/01/2014, 18:20

... occurs. Then although the database at the beginning of the dump has values (1.2.3, A), and the database at the end of the dump has values (5.7.6,4). the copy of the database in the archie ... from the archive. (a) Find the most recent full dump and reconstruct the database from it (i.e., copy the archise into the database) . (b) If there are l...

Ngày tải lên: 21/01/2014, 18:20

Ngày tải lên: 24/12/2013, 12:17

Ngày tải lên: 24/12/2013, 12:17

Ngày tải lên: 24/12/2013, 12:17

... the block move under the disk head as the entire disk assembly rotates. The time taken between the moment at which the command to read a block is issued and the time that the contents of the ... latency: the time for the disk to rotate so the first of the sectors containing the block reaches the head. X typical disk rotates completely about once every 10 mi...

Ngày tải lên: 21/01/2014, 18:20

... room for the inserted record in the block at hand, then we simply slide the records within the block and adjust the pointers in the offset table. The new record is inserted into the block, ... having to retrieve the block containing the record. The fact that K exists in the dense index is enough to guarantee the existence of the record with key I(. On th...

Ngày tải lên: 21/01/2014, 18:20