On 07-08-2018 19:21, Fabien COELHO wrote:
Hello Marina,
Hello, Fabien!
v10-0001-Pgbench-errors-use-the-RandomState-structure-for.patch
- a patch for the RandomState structure (this is used to reset a
client's random seed during the repeating of transactions after
serialization/deadlock failures).
About this v10 part 1:
Patch applies cleanly, compile, global & local make check both ok.
The random state is cleanly separated so that it will be easy to reset
it on client error handling ISTM that the pgbench side is
deterministic with
the separation of the seeds for different uses.
Code is clean, comments are clear.
:-)
I'm wondering what is the rational for the "xseed" field name? In
particular, what does the "x" stands for?
I called it "...seed" instead of "data" because perhaps the "data" is
too general a name for use here (but I'm not entirely sure what Alvaro
Herrera meant in [1], see my answer in [2]). I called it "xseed" to
combine it with the arguments of the functions _dorand48 / pg_erand48 /
pg_jrand48 in the file erand48.c. IIUC they use a linear congruential
generator and perhaps "xseed" means the sequence with the name X of
pseudorandom values of size 48 bits (X_0, X_1, ... X_n) where X_0 is the
seed / the start value.
[1]
https://www.postgresql.org/message-id/20180711180417.3ytmmwmonsr5lra7@alvherre.pgsql
LGTM, though I'd rename the random_state struct members so that it
wouldn't look as confusing. Maybe that's just me.
[2]
https://www.postgresql.org/message-id/cb2cde10e4e7a10a38b48e9cae8fbd28%40postgrespro.ru
--
Marina Polyakova
Postgres Professional: http://www.postgrespro.com
The Russian Postgres Company
