Josh Kupershmidt <schmiddy@xxxxxxxxx> writes: > I made a small half-empty table like this: > CREATE TABLE test_vacuum (i int PRIMARY KEY); > INSERT INTO test_vacuum (i) SELECT a FROM generate_series(1,500000) AS a; > DELETE FROM test_vacuum WHERE RANDOM() < 0.5; > and then ran: > VACUUM test_vacuum; > while an strace of the stats collector process was running. Then after > a few seconds, found the PID of the VACUUM process, and ran strace on > it. I killed them after the VACUUM finished. Outputs attached. Huh. The VACUUM strace clearly shows a boatload of TABPURGE messages being sent: sendto(7, "\2\0\0\0\350\3\0\0\5@\0\0\366\0\0\0\324\206<\24\321uC\24\320\350)\24\225\345,\24"..., 1000, 0, NULL, 0) = 1000 sendto(7, "\2\0\0\0\350\3\0\0\5@\0\0\366\0\0\0C\274?\24\365\323?\24\241N@\24\217\0309\24"..., 1000, 0, NULL, 0) = 1000 sendto(7, "\2\0\0\0\350\3\0\0\5@\0\0\366\0\0\0\375Z2\24\211\f@\0241\3047\24\357mH\24"..., 1000, 0, NULL, 0) = 1000 sendto(7, "\2\0\0\0\350\3\0\0\5@\0\0\366\0\0\0\242\3529\24\234K\'\24\17\227)\24\300\22+\24"..., 1000, 0, NULL, 0) = 1000 and the stats collector is receiving them: recvfrom(7, "\2\0\0\0\350\3\0\0\5@\0\0\366\0\0\0\324\206<\24\321uC\24\320\350)\24\225\345,\24"..., 1000, 0, NULL, NULL) = 1000 recvfrom(7, "\2\0\0\0\350\3\0\0\5@\0\0\366\0\0\0C\274?\24\365\323?\24\241N@\24\217\0309\24"..., 1000, 0, NULL, NULL) = 1000 recvfrom(7, "\2\0\0\0\350\3\0\0\5@\0\0\366\0\0\0\375Z2\24\211\f@\0241\3047\24\357mH\24"..., 1000, 0, NULL, NULL) = 1000 So this *should* have resulted in the stats file shrinking. Did you happen to notice if it did, after you did this? regards, tom lane -- Sent via pgsql-performance mailing list (pgsql-performance@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-performance
