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| author | Noah Misch <noah@leadboat.com> | 2018-09-23 22:56:39 -0700 |
|---|---|---|
| committer | Noah Misch <noah@leadboat.com> | 2018-09-23 22:56:42 -0700 |
| commit | 4232cff11b84ddb7440bc2fdc3a5bd6ab0baeea4 (patch) | |
| tree | 55ab1b29e562598ba81b48c1bc6e7083131fa7ae /src/backend/executor/execParallel.c | |
| parent | 5ed281e21d363aa1661587c331a022d7e6763d0c (diff) | |
| download | postgresql-4232cff11b84ddb7440bc2fdc3a5bd6ab0baeea4.tar.gz postgresql-4232cff11b84ddb7440bc2fdc3a5bd6ab0baeea4.zip | |
Initialize random() in bootstrap/stand-alone postgres and in initdb.
This removes a difference between the standard IsUnderPostmaster
execution environment and that of --boot and --single. In a stand-alone
backend, "SELECT random()" always started at the same seed.
On a system capable of using posix shared memory, initdb could still
conclude "selecting dynamic shared memory implementation ... sysv".
Crashed --boot or --single postgres processes orphaned shared memory
objects having names that collided with the not-actually-random names
that initdb probed. The sysv fallback appeared after ten crashes of
--boot or --single postgres. Since --boot and --single are rare in
production use, systems used for PostgreSQL development are the
principal candidate to notice this symptom.
Back-patch to 9.3 (all supported versions). PostgreSQL 9.4 introduced
dynamic shared memory, but 9.3 does share the "SELECT random()" problem.
Reviewed by Tom Lane and Kyotaro HORIGUCHI.
Discussion: https://postgr.es/m/20180915221546.GA3159382@rfd.leadboat.com
Diffstat (limited to 'src/backend/executor/execParallel.c')
0 files changed, 0 insertions, 0 deletions