diff options
| author | Tom Lane <tgl@sss.pgh.pa.us> | 2021-11-28 21:32:36 -0500 |
|---|---|---|
| committer | Tom Lane <tgl@sss.pgh.pa.us> | 2021-11-28 21:33:07 -0500 |
| commit | 3804539e48e794781c6145c7f988f5d507418fa8 (patch) | |
| tree | 317904b43ca8c1d510b23cb8fdd7b05a75e971bc /src/backend/access/gin/ginget.c | |
| 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 'src/backend/access/gin/ginget.c')
| -rw-r--r-- | src/backend/access/gin/ginget.c | 3 |
1 files changed, 2 insertions, 1 deletions
diff --git a/src/backend/access/gin/ginget.c b/src/backend/access/gin/ginget.c index 03191e016ce..e93bf299990 100644 --- a/src/backend/access/gin/ginget.c +++ b/src/backend/access/gin/ginget.c @@ -16,6 +16,7 @@ #include "access/gin_private.h" #include "access/relscan.h" +#include "common/pg_prng.h" #include "miscadmin.h" #include "storage/predicate.h" #include "utils/datum.h" @@ -787,7 +788,7 @@ entryLoadMoreItems(GinState *ginstate, GinScanEntry entry, } } -#define gin_rand() (((double) random()) / ((double) MAX_RANDOM_VALUE)) +#define gin_rand() pg_prng_double(&pg_global_prng_state) #define dropItem(e) ( gin_rand() > ((double)GinFuzzySearchLimit)/((double)((e)->predictNumberResult)) ) /* |