Without this, the connection will be killed after timeout if
wal_sender_timeout is set in the server.
Original patch by Amit Kapila, modified by me to fit recent changes in the
code.
We used to send structs wrapped in CopyData messages, which works as long as
the client and server agree on things like endianess, timestamp format and
alignment. That's good enough for running a standby server, which has to run
on the same platform anyway, but it's useful for tools like pg_receivexlog
to work across platforms.
This breaks protocol compatibility of streaming replication, but we never
promised that to be compatible across versions, anyway.
We had a number of variants on the theme of "malloc or die", with the
majority named like "pg_malloc", but by no means all. Standardize on the
names pg_malloc, pg_malloc0, pg_realloc, pg_strdup. Get rid of pg_calloc
entirely in favor of using pg_malloc0.
This is an essentially cosmetic change, so no back-patch. (I did find
a couple of places where psql and pg_dump were using plain malloc or
strdup instead of the pg_ versions, but they don't look significant
enough to bother back-patching.)
timeval.t_sec is of type time_t, which is not always compatible with long.
I'm not sure if this was just harmless warning or a real bug, but this
fixes it, anyway.
In particular, with a controlled shutdown of the master, pg_basebackup
with streaming log could terminate without an error message, even though
the backup is not consistent.
In passing, fix a few cases where walfile wasn't properly set to -1 after
closing.
Fujii Masao
The most user-visible part of this is to change the long options
--statusint and --noloop to --status-interval and --no-loop,
respectively, per discussion.
Also, consistently enclose file names in double quotes, per our
conventions; and consistently use the term "transaction log file" to
talk about WAL segments. (Someday we may need to go over this
terminology and make it consistent across the whole source code.)
Finally, reflow the code to better fit in 80 columns, and have pgindent
fix it up some more.
When the internal loop mode was added, freeing memory and closing
filedescriptors before returning became important, and a few cases
in the code missed that.
Fujii Masao
This makes it possible for the master to track how much data has
actually been written my pg_receivexlog - and not just how much
has been sent towards it.
This simplifies code that needs to do arithmetic on XLogRecPtrs.
To avoid changing on-disk format of data pages, the LSN on data pages is
still stored in the old format. That should keep pg_upgrade happy. However,
we have XLogRecPtrs embedded in the control file, and in the structs that
are sent over the replication protocol, so this changes breaks compatibility
of pg_basebackup and server. I didn't do anything about this in this patch,
per discussion on -hackers, the right thing to do would to be to change the
replication protocol to be architecture-independent, so that you could use
a newer version of pg_receivexlog, for example, against an older server
version.
The comments claimed that wasting the last segment made it easier to do
calculations with XLogRecPtrs, because you don't have problems representing
last-byte-position-plus-1 that way. In my experience, however, it only made
things more complicated, because the there was two ways to represent the
boundary at the beginning of a logical log file: logid = n+1 and xrecoff = 0,
or as xlogid = n and xrecoff = 4GB - XLOG_SEG_SIZE. Some functions were
picky about which representation was used.
Also, use a 64-bit segment number instead of the log/seg combination, to
point to a certain WAL segment. We assume that all platforms have a working
64-bit integer type nowadays.
This is an incompatible change in WAL format, so bumping WAL version number.
Since the replication protocol deals with TimestampTz, we need to
care for the floating point case as well in the frontend tools.
Fujii Masao, with changes from Magnus Hagander
When backing up from a standby server, the backup process
will not automatically switch xlog segment. So we must
accept a partially transferred xlog file in this case, but
rename it into position anyway.
In passing, merge the two callbacks for segment end and
stop stream into a single callback, since their implementations
were close to identical, and rename this callback to
reflect that it stops streaming rather than continues it.
Patch by Magnus Hagander, review by Fujii Masao
Teach pg_basebackup in streaming mode to deal with keepalive messages.
Also change the order of checks to complain at the message rather than
block size when a new message is introduced.
In passing, switch to using sizeof() instead of hardcoded sizes for
WAL protocol structs.
Instead of filling files as they appear, pre-pad the
WAL files received when streaming xlog the same way
that the server does. Data is streamed into a .partial
file which is then renamed()d into palce when it's complete,
but it will always be 16MB.
This also means that the starting position for pg_receivexlog
is now simply right after the last complete segment, and we
never need to deal with partial segments there.
Patch by me, review by Fujii Masao
Add option for parallel streaming of the transaction log while a
base backup is running, to get the logfiles before the server has
removed them.
Also add a tool called pg_receivexlog, which streams the transaction
log into files, creating a log archive without having to wait for
segments to complete, thus decreasing the window of data loss without
having to waste space using archive_timeout. This works best in
combination with archive_command - suggested usage docs etc coming later.
Heikki Linnakangas
Tom Lane
Peter Eisentraut
Magnus Hagander
Alvaro Herrera
Bruce Momjian