return me the total citations of all the papers in PVLDB .
SELECT SUM ( t2.citation_num ) FROM publication AS t2 JOIN journal AS t1 ON t2.jid  =  t1.jid WHERE t1.name  =  "PVLDB";
SELECT SUM ( t2.citation_num ) FROM publication AS t2 JOIN journal AS t1 ON t2.jid  =  t1.jid WHERE t1.name  =  "PVLDB";
[{'SUM ( t2.citation_num )': None}]