GATE CSE 2020
Q51.
Consider a relational database containing the following schemas. The primary key of each table is indicated by underlining the constituent fields. SELECT s.sno, s.sname FROM Suppliers s, Catalogue c WHERE s.sno=c.sno AND cost > (SELECT AVG (cost) FROM Catalogue WHERE pno = 'P4' GROUP BY pno) ;The number of rows returned by the above SQL query isQ52.
Consider a schedule of transactions T1 and T2: Here, RX stands for "Read(X)" and WX stands for "Write(X)". Which one of the following schedules is conflict equivalent to the above schedule?Q53.
Which of the following languages are undecidable? Note that \left \langle M \right \rangle indicates encoding of the Turing machine M. L_1=\{\left \langle M \right \rangle|L(M)=\varnothing \} L_2={\left \langle M,w,q \right \rangle|M on input w reaches state q in exactly 100 steps} L_3=\{\left \langle M \right \rangle|L(M) \;is \; not \; recursive\} L_4=\{\left \langle M \right \rangle|L(M) \;contains \; at \; least\; 21 \; members\}Q54.
Consider a TCP connection between a client and a server with the following specifications; the round trip time is 6 ms, the size of the receiver advertised window is 50 KB, slow-start threshold at the client is 32 KB, and the maximum segment size is 2 KB. The connection is established at time t=0. Assume that there are no timeouts and errors during transmission. Then the size of the congestion window (in KB) at time t+60 ms after all acknowledgements are processed is _______