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| 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 /contrib/amcheck | |
| parent | f44ceb46ec2d8da48f6e145bf462d5620c25e079 (diff) | |
| download | postgresql-3804539e48e794781c6145c7f988f5d507418fa8.tar.gz | |
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/amcheck')
| -rw-r--r-- | contrib/amcheck/verify_nbtree.c | 5 |
1 files changed, 3 insertions, 2 deletions
diff --git a/contrib/amcheck/verify_nbtree.c b/contrib/amcheck/verify_nbtree.c index 42a830c33b..dc1508b636 100644 --- a/contrib/amcheck/verify_nbtree.c +++ b/contrib/amcheck/verify_nbtree.c @@ -32,6 +32,7 @@ #include "catalog/index.h" #include "catalog/pg_am.h" #include "commands/tablecmds.h" +#include "common/pg_prng.h" #include "lib/bloomfilter.h" #include "miscadmin.h" #include "storage/lmgr.h" @@ -466,8 +467,8 @@ bt_check_every_level(Relation rel, Relation heaprel, bool heapkeyspace, total_pages = RelationGetNumberOfBlocks(rel); total_elems = Max(total_pages * (MaxTIDsPerBTreePage / 3), (int64) state->rel->rd_rel->reltuples); - /* Random seed relies on backend srandom() call to avoid repetition */ - seed = random(); + /* Generate a random seed to avoid repetition */ + seed = pg_prng_uint64(&pg_global_prng_state); /* Create Bloom filter to fingerprint index */ state->filter = bloom_create(total_elems, maintenance_work_mem, seed); state->heaptuplespresent = 0; |