diff options
| author | Tom Lane | 2021-11-29 02:32:36 +0000 |
|---|---|---|
| committer | Tom Lane | 2021-11-29 02:33:07 +0000 |
| commit | 3804539e48e794781c6145c7f988f5d507418fa8 (patch) | |
| tree | 317904b43ca8c1d510b23cb8fdd7b05a75e971bc /contrib/auto_explain | |
| parent | f44ceb46ec2d8da48f6e145bf462d5620c25e079 (diff) | |
Replace random(), pg_erand48(), etc with a better PRNG API and algorithm.
Standardize on xoroshiro128** as our basic PRNG algorithm, eliminating
a bunch of platform dependencies as well as fundamentally-obsolete PRNG
code. In addition, this API replacement will ease replacing the
algorithm again in future, should that become necessary.
xoroshiro128** is a few percent slower than the drand48 family,
but it can produce full-width 64-bit random values not only 48-bit,
and it should be much more trustworthy. It's likely to be noticeably
faster than the platform's random(), depending on which platform you
are thinking about; and we can have non-global state vectors easily,
unlike with random(). It is not cryptographically strong, but neither
are the functions it replaces.
Fabien Coelho, reviewed by Dean Rasheed, Aleksander Alekseev, and myself
Discussion: https://postgr.es/m/alpine.DEB.2.22.394.2105241211230.165418@pseudo
Diffstat (limited to 'contrib/auto_explain')
| -rw-r--r-- | contrib/auto_explain/auto_explain.c | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/contrib/auto_explain/auto_explain.c b/contrib/auto_explain/auto_explain.c index e9092ba359a..59ba63455fd 100644 --- a/contrib/auto_explain/auto_explain.c +++ b/contrib/auto_explain/auto_explain.c @@ -16,6 +16,7 @@ #include "access/parallel.h" #include "commands/explain.h" +#include "common/pg_prng.h" #include "executor/instrument.h" #include "jit/jit.h" #include "utils/guc.h" @@ -275,8 +276,7 @@ explain_ExecutorStart(QueryDesc *queryDesc, int eflags) if (nesting_level == 0) { if (auto_explain_log_min_duration >= 0 && !IsParallelWorker()) - current_query_sampled = (random() < auto_explain_sample_rate * - ((double) MAX_RANDOM_VALUE + 1)); + current_query_sampled = (pg_prng_double(&pg_global_prng_state) < auto_explain_sample_rate); else current_query_sampled = false; } |