Chapter 10
... • Lock guarantees unique access to a data item by transaction • Two types of locks: binary locks and shared/exclusive locks Database Systems, 8th Edition ...
... • Lock guarantees unique access to a data item by transaction • Two types of locks: binary locks and shared/exclusive locks Database Systems, 8th Edition ...
Overview of Databases and Transaction Processing
... does not lose data, controlled concurrency • High Throughput: many users => many transactions/sec • Low Response Time: on-line => users are waiting ...
... does not lose data, controlled concurrency • High Throughput: many users => many transactions/sec • Low Response Time: on-line => users are waiting ...
Transactions
... If a transaction Ti is aborted, all its actions have to be undone. Not only that, if Tj reads an object last written by Ti, Tj must be aborted as well! Most systems avoid such cascading aborts by releasing a transaction’s locks only at commit time. ...
... If a transaction Ti is aborted, all its actions have to be undone. Not only that, if Tj reads an object last written by Ti, Tj must be aborted as well! Most systems avoid such cascading aborts by releasing a transaction’s locks only at commit time. ...
Transaction Processing and Recovery
... are the same as the results of running them serially —that is, one after the other. It is not important which transaction executes first, only that the result does not reflect any mixing of the transactions. Serializability is the major correctness criterion for the execution of concurrent transacti ...
... are the same as the results of running them serially —that is, one after the other. It is not important which transaction executes first, only that the result does not reflect any mixing of the transactions. Serializability is the major correctness criterion for the execution of concurrent transacti ...
LM9 PowerPoints Slides
... • A single logical database spread physically across computers in multiple locations that are connected by a data communications link • Decentralized Database - A collection of independent databases on non-networked computers ...
... • A single logical database spread physically across computers in multiple locations that are connected by a data communications link • Decentralized Database - A collection of independent databases on non-networked computers ...
Database Systems: Design, Implementation, and Management
... – Still possible to use “roll back – see SQL note for more details” as a recovery mechanism. – Roll back: go back to the previous state ...
... – Still possible to use “roll back – see SQL note for more details” as a recovery mechanism. – Roll back: go back to the previous state ...
Multi-user DB lecture
... two or more transactions have locked a common resource and must wait for the other to unlock that resource user 1 has a locked record and needs a lock on another record; user 2 has lock on record user 1 wants and needs lock on user 1’s record see figures 12-13, 12-14 ...
... two or more transactions have locked a common resource and must wait for the other to unlock that resource user 1 has a locked record and needs a lock on another record; user 2 has lock on record user 1 wants and needs lock on user 1’s record see figures 12-13, 12-14 ...
Chapter 2 Notes
... Result: Database state no longer corresponds to real-world state, integrity constraint violated. ...
... Result: Database state no longer corresponds to real-world state, integrity constraint violated. ...
Document
... Concurrency Control with Optimistic Methods • Optimistic approach – Based on the assumption that the majority of database operations do not conflict – Does not require locking or time stamping techniques – Transaction is executed without restrictions until it is committed – Phases are read, validat ...
... Concurrency Control with Optimistic Methods • Optimistic approach – Based on the assumption that the majority of database operations do not conflict – Does not require locking or time stamping techniques – Transaction is executed without restrictions until it is committed – Phases are read, validat ...
Transactions
... • Durability requirement — once the user has been notified that the transaction has completed (i.e., the transfer of the $50 has taken place), the updates to the database by the transaction must persist even if there are software or hardware failures. ...
... • Durability requirement — once the user has been notified that the transaction has completed (i.e., the transfer of the $50 has taken place), the updates to the database by the transaction must persist even if there are software or hardware failures. ...
ppt
... Result: Database state no longer corresponds to real-world state, integrity constraint violated. ...
... Result: Database state no longer corresponds to real-world state, integrity constraint violated. ...
Transaction manager
... (a) If two transactions only read a data item, they do not conflict and order is not important. (b) If two transactions either read or write completely separate data items, they do not conflict and order is not important. (c) If one transaction writes a data item and another reads or writes same dat ...
... (a) If two transactions only read a data item, they do not conflict and order is not important. (b) If two transactions either read or write completely separate data items, they do not conflict and order is not important. (c) If one transaction writes a data item and another reads or writes same dat ...
A Closer Look
... Result: Database state no longer corresponds to real-world state, integrity constraint violated. ...
... Result: Database state no longer corresponds to real-world state, integrity constraint violated. ...
A Closer Look
... • Example: course registration (cur_reg is number of current registrants) T1: r(cur_reg : 29) w(cur_reg : 30) T2: r(cur_reg : 29) w(cur_reg : 30) time ...
... • Example: course registration (cur_reg is number of current registrants) T1: r(cur_reg : 29) w(cur_reg : 30) T2: r(cur_reg : 29) w(cur_reg : 30) time ...
Applying Database Replication to Multi
... • Read-one / Write-All replication only scales if the percentage of reads is very high. • Future work: use partial replication (Write only a few servers) ...
... • Read-one / Write-All replication only scales if the percentage of reads is very high. • Future work: use partial replication (Write only a few servers) ...
Neo4j - IDEAL
... Neo4j is schema free – Data does not have to adhere to any convention ACID – atomic, consistent, isolated and durable for logical units of work Easy to get started and use Well documented and large developer ...
... Neo4j is schema free – Data does not have to adhere to any convention ACID – atomic, consistent, isolated and durable for logical units of work Easy to get started and use Well documented and large developer ...
slides
... • Transaction aborted by system – Execution cannot be made atomic (a site is down) – Execution did not maintain database consistency (integrity constraint is violated) – Execution was not isolated – Resources not available (deadlock) ...
... • Transaction aborted by system – Execution cannot be made atomic (a site is down) – Execution did not maintain database consistency (integrity constraint is violated) – Execution was not isolated – Resources not available (deadlock) ...
File Systems and Databases Assessment
... more familiar with the regular pcs and work stations rather than the main frame computers. This is why DDBMS gives the user-friendly and easy interface to users. The three disadvantages of a DDBMS are:1. Complexity of management and control – In DDBMS, transaction management, concurrency control, da ...
... more familiar with the regular pcs and work stations rather than the main frame computers. This is why DDBMS gives the user-friendly and easy interface to users. The three disadvantages of a DDBMS are:1. Complexity of management and control – In DDBMS, transaction management, concurrency control, da ...
