Re: [WIP] Zipfian distribution in pgbench

From: Fabien COELHO <coelho(at)cri(dot)ensmp(dot)fr>
To: Alik Khilazhev <a(dot)khilazhev(at)postgrespro(dot)ru>
Cc: PostgreSQL Developers <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: [WIP] Zipfian distribution in pgbench
Date: 2017-09-06 06:42:15
Message-ID: alpine.DEB.2.20.1709060838320.17848@lancre
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Hello Alik,

Applies, compiles, works for me.

Some minor comments and suggestions.

Two typos:
- "usinng" -> "using"
- "a rejection method used" -> "a rejection method is used"

I'm not sure of "least_recently_used_i", this naming style is not used in
pgbench. "least_recently_used" would be ok.

"..nb_cells.. != ZIPF_CACHE_SIZE", ISTM that "<" is more logical,
even if the result is the same?

I would put the parameter value check in getZipfianRand, so that if
someone reuse the function elsewhere the check is also performed. That
would also simplify a bit the already very large expression evaluation

When/if the pgbench tap test patch get through, coverage tests should
be added.

Maybe the cache overflow could be counted, to allow for a possible warning
message in the final report?


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