Hello, I've been wondering how pgsql goes about guaranteeing data integrity in the face of soft failures. In particular whether it uses an alternative to the double root block technique - which is writing, as a final indication of the validity of new log records, to alternate disk blocks at fixed disk locations some meta information including the location of the last log record written. This is the only technique I know of - does pgsql use something analogous?
Also, I note from the developer docs the comment on cacheing disk drives: can anyone supply a reference on this subject (I have been on the lookout for a long time without success) and perhaps more generally on the subject of what exactly can go wrong with a disk write when struck by power failure. Lastly, is there any form of integrity checking on disk block level data? I have vague recollections of seeing mention of crc/xor in relation to Oracle or DB2. Whether or not pgsql uses any such scheme I am curious to know a rationale for its use - it makes me wonder about what, if anything, can be relied on 100%! Thanks, Chris Quinn ---------------------------(end of broadcast)--------------------------- TIP 1: subscribe and unsubscribe commands go to [EMAIL PROTECTED]
