Components of a ddbms User processor User interface handler requests Semantic data controller ROCESSOR ser Interfac Extem Global query optimizer and decomposer Overy Distributed execution monitor Global Execute Data processor OCESSOR Local query optimizer Query Processc Local recovery manager Recovery Manag Log Run-time support processor Local Inter Processor 2021/2/1 WAMDM Cloud Group
Components of a DDBMS • User processor – User interface handler – Semantic data controller – Global query optimizer and decomposer – Distributed execution monitor • Data processor – Local query optimizer – Local recovery manager – Run-time support processor • 2021/2/11 WAMDM Cloud Group 6
MDBS Architecture With a gcs Without gcs GES ges IGEs E ES n LES, LES, LES Multidatabase Local system LCS ayer LCS LCS LCS LIS, LIS LIS >GCS, GES may use different data model and language Local system layer >Homogeneous >Unilingual(example: MULITIBASE Multidatabase layer Multilingual(permit each user to access the global data by means of external schema) >heterogeneous WAMDM Cloud Group
MDBS Architecture With a GCS Without GCS 2021/2/11 WAMDM Cloud Group 7 ➢GCS,GES may use different data model and language ➢Homogeneous: ➢Unilingual(example:MULITIBASE) ➢ Multilingual(permit each user to access the global data by means of external schema) ➢heterogeneous ➢Local system layer ➢Multidatabase layer
Difference between mdbs and ddbms Definition difference DDBMS MDBS Global conceptual schema The conceptual view of the The collection of some of (fundamental difference) entire database, mapping the local db that wants to the global schema to local share, mapping the local conceptual schema onceptual schema to a global schema Global database Equal to the union of local A subset of the union of databases the local databases Design strategy Usually designed by top- Usually designed by down process bottom-up process 2021/2/1 WAMDM Cloud Group
Difference between MDBS and DDBMS Definition difference DDBMS MDBs Global conceptual schema (fundamental difference) The conceptual view of the entire database, mapping the global schema to local conceptual schema The collection of some of the local DB that wants to share, mapping the local conceptual schema to a global schema Global database Equal to the union of local databases A subset of the union of the local databases Design strategy Usually designed by topdown process Usually designed by bottom-up process 2021/2/11 WAMDM Cloud Group 8
Outline Architecture Client/Server, P2P DDBMS. MDBS Design Strategies Issues Fragmentation Allocation Conclusion 2021/2/1 WAMDM Cloud Group
Outline • Architecture – Client/Server, P2P – DDBMS,MDBS • Design – Strategies – Issues – Fragmentation – Allocation • Conclusion 2021/2/11 WAMDM Cloud Group 9
Framework of distribution evel of sharing Share nothing Access pattern Share data D Share da re datat progra Static Partial ° Access pattern nformation Stati ata Level of knowledge Dynamic vel of knowledge or Complete Data nformation program access pattern Know nothing The designer know partial information The designer know complete information 2021/2/1 WAMDM Cloud Group
Framework of Distribution • Level of sharing – Share nothing – Share data – Share data+ program • Access pattern – Static – Dynamic • Level of knowledge on access pattern – Know nothing – The designer know partial information – The designer know complete information 2021/2/11 WAMDM Cloud Group 10