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The Concurrency Control Problem in Multidatabases: Characteristics and Solutions
| Content Provider | Semantic Scholar |
|---|---|
| Copyright Year | 1991 |
| Abstract | TO scheme, transactions are serialized in timestamp order, if T i is serialized before T j in S k , T i ; T j 2 k , then T i 's timestamp must be smaller than T j 's times-tamp. Thus, in S k , T i must have been assigned a timestamp before T j is assigned one (assuming timestamps are assigned in an increasing order). 2 Lemma 16: If site s k follows a validation protocol, then any function that maps every transaction T i 2 k to its operation that results in its validation is a serialization function for s k. Proof: Since validation protocols ensure that transactions are serialized in the order in which they are validated, if T i is serialized before T j in S k , T i ; T j 2 k , then T i must have been validated in S k before T j is validated. 2 48-Appendix E-Central to the design of any of the schemes to ensure global serializability is the requirement that GTM 1 be able to determine operations in ser(S). A serialization function for site s k depends on the concurrency control protocol followed by s k. Lemma 14: If site s k follows the 2PL protocol, then any function that maps every transaction T i 2 k to one of its operations that executes between the time T i obtains its last lock and the time it releases its rst lock, is a serialization function for s k. Proof: Let ser be a function that maps every transaction T i 2 k to one of its operations that executes between the time T i obtains its last lock and the time it releases its rst lock. We need to show that for any pair of transactions T i ; T j 2 k , if T i is serialized before T j in S k , then ser(T i) Sk ser(T j). Since T i is serialized before T j in S k , there exist transactions, say, T 1 ; T 2 ; : : : ; T r in S k such that T i con BLOCKINicts with T 1 , T 1 con BLOCKINicts with T 2 , : : :, T r con BLOCKINicts with T j. We show that, in S k , T i releases its rst lock … |
| File Format | PDF HTM / HTML |
| Alternate Webpage(s) | http://www.bell-labs.com/user/rastogi/sigmod92.ps |
| Language | English |
| Access Restriction | Open |
| Content Type | Text |
| Resource Type | Article |
