Thread: pgsql: Add function pg_xlog_location_diff to help comparisons

Add function pg_xlog_location_diff to help comparisons

Comparing two xlog locations are useful for example when calculating
replication lag.

Euler Taveira de Oliveira, reviewed by Fujii Masao, and some cleanups
from me

Branch
------
master

Details
-------
http://git.postgresql.org/pg/commitdiff/bc5ac3686580079bd4ea26bf027178786d77a9ee

Modified Files
--------------
doc/src/sgml/func.sgml                 |   20 +++++++-
src/backend/access/transam/xlogfuncs.c |   90 ++++++++++++++++++++++++++++++++
src/include/access/xlog_internal.h     |    1 +
src/include/catalog/catversion.h       |    2 +-
src/include/catalog/pg_proc.h          |    3 +
5 files changed, 114 insertions(+), 2 deletions(-)