View update and temporal correctness in real-time database systems

by Cheng, Chun-kong

(Uncorrected OCR) Abstract of Thesis Entitled "View Update and Temporal Correctness in RealTime Database Systems" Submitted by Cheng Chun Kong For the Degree of Master of Philosophy at The University of Hong Kong in June 2000 A realtime daabase sys suppors daabase operaons wit realtime con ra conns base da its whi record and ode a physcal rea word envronent. For better decon support, base da its are summarized and correted o derve vews These base daa and vews are accessed by appi caon ransacons o genera e ultime acons aken by e sysm. As envronen anges updaes are apped e base da hi subsequen gger vew recopuons. There are hus ree ypes of acites: base da upda ew recopuon and applicaon ransacon execuon n suc sysm, two iming consras need o be enforced. We requre ap licaon ransacons eet tr deadnes (ransacon imliness) and read fres daa (da imness). These wo requreens pose confng deands on sys resources. To keep e daa fresh, updaes and recopuons ave be applied proy. The copuonal load of ese wo acites can be ex re h, causng critca deays ransacons onsequeny, transacons ave a hier cance of missng r deadnes ess we define e concep of absoe and reve pora cons ency from te perspecve of ransacons. W roduce wo pora correcness critera: absoe consen sys (ACS) and reve consen sys (RCS) We sudy ree sceduling poes, nay URT, OD and OD for scedung ree ypes of acites. We aso dscuss ow ese scedung poes sou be desgned o sasfy iming requreens of ACS and RCS so t transac on and da imliness can be . We argue OD en apped o an RCS ll result i owes nuber of missed deadnes