Tài liệu miễn phí Cơ sở dữ liệu

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Một phương pháp phân vùng dữ liệu theo độ tin cậy dựa trên phân cụm mờ viễn cảnh

Bài viết đề xuất một phương pháp mới trong phân vùng dữ liệu theo độ tin cậy dựa trên phân cụm mờ viễn cảnh có tên gọi PT2FCM. Thuật toán đề xuất được so sánh thực nghiệm với một số phương pháp liên quan như phân cụm bán giám sát mờ trên tập mờ viễn cảnh (FCPFS), phân cụm bán giám sát mờ an toàn (CS3FCM), v.v.

4/8/2023 7:15:37 PM +00:00

Tăng cường trọng số BM25 kết hợp mô hình ngữ cảnh cho việc dò tìm báo cáo lỗi trùng nhau

Những báo cáo lỗi được những người sử dụng gửi thường được lưu trữ và quản lý bởi những hệ thống quản lý lỗi của những dự án phần mềm nguồn mở như Open Office, Mozilla Firefox, Eclipse... Trong bài viết này, nhóm tác giả giới thiệu một phương pháp mới tự động dò tìm những báo cáo lỗi trùng nhau bằng cách sử dụng mô hình LDANWF (Latent Dirichlet Allocation-New Weight Feature).

4/8/2023 6:17:26 PM +00:00

Distributed Database Management Systems: Lecture 35

Distributed Database Management Systems: Lecture 35. The main topics covered in this chapter include: query optimization and fragmented queries; joins replaced by semijoins; three major QO algorithms; distributed query processing algorithms;...

4/8/2023 5:44:33 PM +00:00

Distributed Database Management Systems: Lecture 34

Distributed Database Management Systems: Lecture 34. The main topics covered in this chapter include: query optimization; centralized QO; best access path; join processing; QO in distributed environment; single relation queries: executed according to the best access path;...

4/8/2023 5:44:27 PM +00:00

Distributed Database Management Systems: Lecture 33

Distributed Database Management Systems: Lecture 33. The main topics covered in this chapter include: data localization for hybrid fragmentation; query optimization; HyF contains both types of fragmentations; QO refers to producing a query execution plan (QEP) that represents execution strategy;...

4/8/2023 5:44:20 PM +00:00

Distributed Database Management Systems: Lecture 32

Distributed Database Management Systems: Lecture 32. The main topics covered in this chapter include: final phase of QD; next phase of query optimization: data localization; idempotency of unary Ops; commuting selection with projection;...

4/8/2023 5:44:14 PM +00:00

Distributed Database Management Systems: Lecture 31

Distributed Database Management Systems: Lecture 31. The main topics covered in this chapter include: query decomposition; steps in query processing; SQL query on distributed relations; optimized fragment query with communication operations;...

4/8/2023 5:44:07 PM +00:00

Distributed Database Management Systems: Lecture 30

Distributed Database Management Systems: Lecture 30. The main topics covered in this chapter include: basic concepts of query optimization; QP in centralized and distributed DBs; query processor transforms complex queries into concise and simple ones;...

4/8/2023 5:44:00 PM +00:00

Distributed Database Management Systems: Lecture 29

Distributed Database Management Systems: Lecture 29. The main topics covered in this chapter include: locking based CC; timestamp ordering based CC; TM sends ops and other information to LM; LM checks the status of data item;...

4/8/2023 5:43:52 PM +00:00

Distributed Database Management Systems: Lecture 28

Distributed Database Management Systems: Lecture 28. The main topics covered in this chapter include: serializability theory; serializability theory in DDBS; equivalent schedules; serializable schedule; fragmented databases; replicated databases;...

4/8/2023 5:43:46 PM +00:00

Distributed Database Management Systems: Lecture 27

Distributed Database Management Systems: Lecture 27. The main topics covered in this chapter include: ACID properties; types of transaction; transaction in DDBS; isolation and consistency are interrelated, one supports other; degree 3 provides full isolation;...

4/8/2023 5:43:35 PM +00:00

Distributed Database Management Systems: Lecture 26

Distributed Database Management Systems: Lecture 26. The main topics covered in this chapter include: transaction management with basics and properties of transaction; database consistency; a transaction is a logical unit of work; consistent transaction;...

4/8/2023 5:43:29 PM +00:00

Distributed Database Management Systems: Lecture 25

Distributed Database Management Systems: Lecture 25. The main topics covered in this chapter include: derived horizontal fragmentation; fragmenting/partitioning a table based on the constraints defined on another table; linked with each other through Owner-Member relation;...

4/8/2023 5:43:23 PM +00:00

Distributed Database Management Systems: Lecture 24

Distributed Database Management Systems: Lecture 24. The main topics covered in this chapter include: fragmentation; design phase and have got the predicates to be used as basis for PHF; name our fragments/local tables as custQTA, custPESH;...

4/8/2023 5:43:17 PM +00:00

Distributed Database Management Systems: Lecture 23

Distributed Database Management Systems: Lecture 23. The main topics covered in this chapter include: created the agents (Snapshot agent and Distributor agent); also the subscription database at the subscriber server (PESH in our case); agents are created, not worked yet, so no snapshot created at the subscriber;...

4/8/2023 5:43:11 PM +00:00

Distributed Database Management Systems: Lecture 22

Distributed Database Management Systems: Lecture 22. The main topics covered in this chapter include: setting up replication; install multiple instances of SQL Server on your computer; this simple setup will work with Windows XP and Personal Edition of SQL Server;...

4/8/2023 5:43:04 PM +00:00

Distributed Database Management Systems: Lecture 21

Distributed Database Management Systems: Lecture 21. The main topics covered in this chapter include: types of fragmentation with horizontal fragmentation, vertical fragmentation; storing a separate copy of database at each of two or three or more sites;...

4/8/2023 5:42:58 PM +00:00

Distributed Database Management Systems: Lecture 20

Distributed Database Management Systems: Lecture 20. The main topics covered in this chapter include: continue with VF to hybrid fragmentation; allocation problem; replication; VF correctness; primary and derived horizontal fragmentation;...

4/8/2023 5:42:52 PM +00:00

Distributed Database Management Systems: Lecture 19

Distributed Database Management Systems: Lecture 19. The main topics covered in this chapter include: continue with VF to example of VF; partitioning in CA; allocation problem; compute the contribution by placing 3rd attribute at different places in CA;...

4/8/2023 5:42:46 PM +00:00

Distributed Database Management Systems: Lecture 18

Distributed Database Management Systems: Lecture 18. The main topics covered in this chapter include: continue with VF to global affinity measure; bond energy algorithm; find the combination that has the maximum Affinity Measure;...

4/8/2023 5:42:39 PM +00:00

Distributed Database Management Systems: Lecture 17

Distributed Database Management Systems: Lecture 17. The main topics covered in this chapter include: continue with VF to information requirement; attribute affinities; replication of Key attributes does not violate the disjoint ness condition;...

4/8/2023 5:42:33 PM +00:00

Distributed Database Management Systems - vu_Lec_16

Distributed Database Management Systems: Lecture 16. The main topics covered in this chapter include: the inputs required for DHF; the set of partitions for owner; member relation; semi-join predicates between owner and member;...

4/8/2023 5:42:27 PM +00:00

Distributed Database Management Systems: Lecture 15

Distributed Database Management Systems: Lecture 15. The main topics covered in this chapter include: PHF- Minimality of Pr; PHF-COM-MIN algorithm; primary horizontal partitioning algorithm; derived horizontal fragmentation (DHF);...

4/8/2023 5:42:20 PM +00:00

Distributed Database Management Systems: Lecture 14

Distributed Database Management Systems: Lecture 14. The main topics covered in this chapter include: minterm predicates; PHF-requirements; minterm selectivities sel(mi); access frequencies acc(qi); access frequencies minterm acc(mi); completeness example;...

4/8/2023 5:42:14 PM +00:00

Distributed Database Management Systems: Lecture 13

Distributed Database Management Systems: Lecture 13. The main topics covered in this chapter include: interests of the local and head offices mar result following vertical partitions of this table: EMP1(eId, eName, eDept); EMP2(eId, eQual, eSal); degree of fragmentation; correctness rules for fragmentation;...

4/8/2023 5:42:08 PM +00:00

Distributed Database Management Systems: Lecture 12

Distributed Database Management Systems: Lecture 12. The main topics covered in this chapter include: global schema architecture; GCSs in MDBS and logically integrated DDBS is different; design process moves in inverse directions, MDBS design process is bottom up, where as in logically integrated DDBS it is top-down;...

4/8/2023 5:42:02 PM +00:00

Distributed Database Management Systems: Lecture 11

Distributed Database Management Systems: Lecture 11. The main topics covered in this chapter include: major DDBS architectures; client-server architecture; one server multiple clients; server performs most of the data management; query processing; transaction and storage management; peer-to-peer distributed systems;...

4/8/2023 5:41:56 PM +00:00

Distributed Database Management Systems: Lecture 10

Distributed Database Management Systems: Lecture 10. The main topics covered in this chapter include: the functions in ANSI/SPARC architecture; square boxes represent processing functions; DB administrator responsible for internal schema; enterprise admin (conceptual schema);...

4/8/2023 5:41:49 PM +00:00

Distributed Database Management Systems: Lecture 9

Distributed Database Management Systems: Lecture 9. The main topics covered in this chapter include: networks continued, DDBMS architecture; local area network; metropolitan area network; wide area network; maintained during conversation;...

4/8/2023 5:41:42 PM +00:00

Distributed Database Management Systems: Lecture 8

Distributed Database Management Systems: Lecture 8. The main topics covered in this chapter include: derived relational algebra ops; relational calculus; semi join; first-order predicate logic; atomic formula;...

4/8/2023 5:41:32 PM +00:00