Serial reads & lseek calls.
| От | Denis Perchine |
|---|---|
| Тема | Serial reads & lseek calls. |
| Дата | |
| Msg-id | 00061212100601.27884@dyp обсуждение исходный текст |
| Список | pgsql-hackers |
Hello all, lseek(4, 26394624, SEEK_SET) = 26394624 read(4, "@\1\210\1\0 \0 \234\237\304\0008\237\304\0\324\236\304"..., 8192) = 8192 lseek(4, 26402816, SEEK_SET) = 26402816 read(4, "@\1\210\1\0 \0 \234\237\304\0008\237\304\0\324\236\304"..., 8192) = 8192 lseek(4, 26411008, SEEK_SET) = 26411008 read(4, "@\1\210\1\0 \0 \234\237\304\0008\237\304\0\324\236\304"..., 8192) = 8192 lseek(4, 26419200, SEEK_SET) = 26419200 read(4, "@\1\210\1\0 \0 \234\237\304\0008\237\304\0\324\236\304"..., 8192) = 8192 lseek(4, 26427392, SEEK_SET) = 26427392 read(4, "@\1\210\1\0 \0 \234\237\304\0008\237\304\0\324\236\304"..., 8192) = 8192 lseek(4, 26435584, SEEK_SET) = 26435584 read(4, "@\1\210\1\0 \0 \234\237\304\0008\237\304\0\324\236\304"..., 8192) = 8192 I ran strace -c -p to look what postgres is doing during removing large objects... And I found out that most of the syscalls called are read & lseek. I will not speculate on the idea that if you would like to read lots of data it will be faster to do this in one read call. But calling lseek when you do not need it... It's a little bit too much. -- Sincerely Yours, Denis Perchine ---------------------------------- E-Mail: dyp@perchine.com HomePage: http://www.perchine.com/dyp/ FidoNet: 2:5000/120.5 ----------------------------------
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