High-Performance Parallel Database Processing and Grid Databases- P8: Parallel databases are database systems that are implemented on parallel computing platforms. Therefore, high-performance query processing focuses on query processing, including database queries and transactions, that makes use of parallelism techniques applied to an underlying parallel computing platform in order to achieve high performance. | 330 Chapter 11 Grid Concurrency Control 2 The global transactions currently executing are added to a set which stores all active transactions. The set of active transactions is represented as Active_Trans. 3 The middlewaae appendsa timestamptoevery subtransaction of the global transaction before submitting it to the corresponding database. 4 If there are twoactieeglobalttansantions that sccessmore flranone database site simultaneously thia creates e . louai databases may schedule the subtransactions in conflicting order. The subtransactions are therefore exeeiiteddlnctle acceading to eSetsmeotamp attached to the io g liieveel bo execniinatCe conflicting subtramactieee accerdixo toitse timnotampl 5 When all subtransacfleno oX atiygloCal transaction complete iHc axdoution at all the sites the trennaoiion terminatesaiKiis removeotfromAntiaeoTroon set see details in Teamtmrtc nO hitse ti Note Active_trans cnrOActier_TranclDB rne niffercot. Tli Xenoere lhx set of currently actionglobartransearions imd OietetTr io abrnnitnCdt takes the database siteas anaaeomentondnatoms ie seOof ac-tvetidosac-tions running at haida-abaer néte. Explanation of Figure 113. Lice 1 oeF gmol 13 checksthe number of eeb-transactions of the submitted transaceoni lethsre ioonly nsmginnubarmnemintc then the global transaction ternatiee exeeoting egk atttcmracS en is added in the active set itrne elanOirsubmrtiedimme hately to the database for execution line 3 . If the global transaction has more than one subtransaction that is the transactionaccessesmore thanone databaseite theelotal-order must be followed. Hencei flm ef -mua muatOc operateT toafli ul tn em tk nsof the global transaction. iSlxciebalnoeisiteiloeliiTOeO rethe arnsic esetnn . GiobaS transactions having onlcecesuemannactiom aremteredoet 0 11X3 6 101 and the new set ot iSe eonflicimo eScba- Sransílntions-s formed line 5 . Timeriampsm .
