"Jignesh K. Shah" <J.K.Shah@xxxxxxx> writes: > CLOG data is > not cached in any PostgreSQL shared memory segments The above statement is utterly false, so your trace seems to indicate something broken. Are you sure these were the only reads of pg_clog files? Can you extend the tracing to determine which page of the file got read? I am wondering if your (unspecified) test load was managing to touch more pages of the clog than there is room for in shared memory. regards, tom lane ---------------------------(end of broadcast)--------------------------- TIP 4: Have you searched our list archives? http://archives.postgresql.org