database systems thae complete book 2nd ed

Ngày tải lên: 24/12/2013, 12:17

Ngày tải lên: 24/12/2013, 12:17

Ngày tải lên: 24/12/2013, 12:17

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 ... stdo has the value "Disney" and yr has the value 1990, then the result of the select-from is the bag of the lengths of the movies made by Disney in 199...

Ngày tải lên: 21/01/2014, 18:20

... 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 milliseconds. On the average, the ... and the three gaps between them. Recall that the gaps represent 10% of the circle and sectors the remaining 90%. There are 128 gaps and 128 sectors around the cir...

Ngày tải lên: 21/01/2014, 18:20

... 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 the other hand, the same query, ... addresses and enter them into the translation table if they are not already there. These pointers include both the pointers from records in the block to elseivhere...

Ngày tải lên: 21/01/2014, 18:20

... look at the code at the right level of abstraction. The first, or outer loop, runs through the tuples of S. The other two loops run through the tuples of R. However, xi-e expressed the process ... Whether the set version or the bag version is wanted, the algorithms are es- sentially the same as that of Section 15.4.3, except that the way we handle the copies...

Ngày tải lên: 21/01/2014, 18:20

... shows the complete translation to relational algebra. .&bola the y, the StarsIn from the outer query is joined n-ith the result of the subquery. The selection from the subquery is then ... in the absence of any copy the buffer back to disk, and to the query processor to execute the queries other transactions or system errors. and it starts with the data...

Ngày tải lên: 21/01/2014, 18:20

... iii. The customer selects a seat for the flight; seat data for the flight is ill database element C. io. The system gets the custo~ner.~ credit-card number and appends the bill for the ... represel~ts the real ti111e at 1\-11ich events occur. Dotted lines link the actual events to the tinles at which they theoretically occur - the tiniestamp of the rransacti...

Ngày tải lên: 21/01/2014, 18:20

... of the sale. the place (store) of the sale, the type of item sold, the method of payment (e.g cash or a credit card), and so on. The dependent attribute(s) might be the sales price, the ... Restoring Database State After an Abort: If a transaction aborts but has written values to buffers, then we can restore old values either from the log or from the disk copy...

Ngày tải lên: 26/01/2014, 15:20

... unoccupied. then the "border" represents only a small addition to the volume of the cube (i.e., the number of tuples in the fact table). In that case, the size of the stored data ... be useful unless the set of items inrrolved has high support. The reason is that if the support is low, then the number of instances of the rule is not large, which limits...

Ngày tải lên: 26/01/2014, 15:20

... instance, if the document has 1000 word occurrences, two of which are " ;database. " then the doculllent ~vould be placed at the ,002 coordinate in the dimension cor~esponding to " ;database. " ... be useful unless the set of items inrrolved has high support. The reason is that if the support is low, then the number of instances of the rule is not large...

Ngày tải lên: 26/01/2014, 15:20

... DATABASE SYSTEMS The Complete Book DATABASE SYSTEMS The Complete Book Second Edition Hector Garcia-Molina Jeffrey D. Ullman Jennifer ... chapters, and is designed for all students — those who want to use database systems as well as those who want to get involved in database implementation. The second course, CS245 on database implementation, ... questions design...

Ngày tải lên: 27/10/2014, 00:34