Thread: Is the a "magic number" for WAL files
I would like the "file" command to tell me something other than "data",
yes even though I can tell by the name (and the directory of course).
Hoping someone has something I can slip into /usr/share/misc/magic.mgc
or that directory.
Along the same lines, what info is embedded in the file name? I see that
the second non-zero recently went from 2 to 3. Significance?
0000000100000030000000CF
^
--------------|
On 9 December 2011 18:46, Rob Sargent <robjsargent@gmail.com> wrote: > Along the same lines, what info is embedded in the file name? I see that > the second non-zero recently went from 2 to 3. Significance? > > > 0000000100000030000000CF > ^ > --------------| The WAL file name consists of timeline, segment set/segment block and segment, Once the segment (the last 8 characters of the file name) reaches 000000FE, the next file will have a segment 00000000 but characters 9-16 will increment their value to reflect this wraparound. So it's not any more significant that 1 added to 99 results in it becoming 00 with a 1 before it. -- Thom
On 9 December 2011 18:46, Rob Sargent <robjsargent@gmail.com> wrote: > I would like the "file" command to tell me something other than "data", > yes even though I can tell by the name (and the directory of course). > Hoping someone has something I can slip into /usr/share/misc/magic.mgc > or that directory. You mean something like this?: /* * Each page of XLOG file has a header like this: */ #define XLOG_PAGE_MAGIC 0xD068 /* can be used as WAL version indicator */ Obviously that isn't stable. -- Peter Geoghegan http://www.2ndQuadrant.com/ PostgreSQL Development, 24x7 Support, Training and Services