Christopher Browne cbbrowne at ca.afilias.info
Mon Jul 23 10:01:39 PDT 2007
Chmouel Boudjnah <cboudjnah at squiz.net> writes:
> Everything looks working well my only concerns is the part of the
> documentation advising to analyze the first few headers and see if it
> is commiting before commiting the rest of the files.

The reason to suggest pulling the first few lines is that if things
do, for whatever reason, break down, it is preferable to handle this
in a controlled way (e.g. - where only a small part of the data gets
loaded in) rather than having large batches of transactions fail.

There may be exogenous reasons for failure that don't have to do with
log shipping itself:

 - Suppose a disk goes bad, corrupting part of a log file
 - Suppose you are copying the files to another server, and something
   breaks down with that copy process
 - Suppose the copy process skips/misses a file

If you aren't doing any pre-examination of the data, the processing
may start failing, and in a way that fills log files with
extraordinary quantities of (pretty useless!) error messages.

The recommendation to do a bit of pre-analysis allows you to detect
these problems and alert a human earlier and without filling up disk
space with millions of lines to the effect of:

ERROR:  current transaction is aborted, commands ignored until end of transaction block
-- 
let name="cbbrowne" and tld="cbbrowne.com" in String.concat "@" [name;tld];;
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