Re: PITR COPY Failure (was Point in Time Recovery)

Simon Riggs <simon(at)2ndquadrant(dot)com> writes:
>> The quick and dirty solution would be to dike out the safety check at
>> 4268ff.

> If you take out that check, we still fail because the wasted space at
> the end is causing a "record with zero length" error.

Ugh. I'm beginning to think we ought to revert the patch that added the
don't-split-across-files logic to XLogInsert; that seems to have broken
more assumptions than I realized. That was added here:

2004-02-11 17:55 tgl

* src/: backend/access/transam/xact.c,
backend/access/transam/xlog.c, backend/access/transam/xlogutils.c,
backend/storage/smgr/md.c, backend/storage/smgr/smgr.c,
bin/pg_controldata/pg_controldata.c,
bin/pg_resetxlog/pg_resetxlog.c, include/access/xact.h,
include/access/xlog.h, include/access/xlogutils.h,
include/pg_config_manual.h, include/catalog/pg_control.h,
include/storage/smgr.h: Commit the reasonably uncontroversial parts
of J.R. Nield's PITR patch, to wit: Add a header record to each WAL
segment file so that it can be reliably identified. Avoid
splitting WAL records across segment files (this is not strictly
necessary, but makes it simpler to incorporate the header records).
Make WAL entries for file creation, deletion, and truncation (as
foreseen but never implemented by Vadim). Also, add support for
making XLOG_SEG_SIZE configurable at compile time, similarly to
BLCKSZ. Fix a couple bugs I introduced in WAL replay during recent
smgr API changes. initdb is forced due to changes in pg_control
contents.

There are other ways to do this, for example we could treat the WAL page
headers as variable-size, and stick the file labeling info into the
first page's header instead of making it be a separate record. The
separate-record way makes it easier to incorporate future additions to
the file labeling info, but I don't really think it's critical to allow
for that.

regards, tom lane