Re: misleading comments in pgbench
От | Tatsuo Ishii |
---|---|
Тема | Re: misleading comments in pgbench |
Дата | |
Msg-id | 20091026.092605.96918067.t-ishii@sraoss.co.jp обсуждение исходный текст |
Ответ на | misleading comments in pgbench (Jeff Janes <jeff.janes@gmail.com>) |
Список | pgsql-hackers |
> * Note: TPC-B requires at least 100 bytes per row, and the "filler" > * fields in these table declarations were intended to comply with that. > * But because they default to NULLs, they don't actually take any > * space. We could fix that by giving them non-null default values. > * However, that would completely break comparability of pgbench > * results with prior versions. Since pgbench has never pretended > * to be fully TPC-B compliant anyway, we stick with the historical > * behavior. > > The statement about NULLs applies to the other 3 tables, but > pgbench_accounts.filler is loaded (via COPY) as empty strings, not as > NULLs. When stored into char(84), the empty string takes the full > specified storage. So on my system, rows in pgbench_accounts take up > about 130 bytes, rather than than the about 40 they would with a NULL. Ok, what about this? * Note: TPC-B requires at least 100 bytes per row, and the * "filler" fields in these table declarations were intendedto * comply with that. But because they default to NULLs, they * don't actually take any space(except pgbench_accounts * table. It's filled with spaces by pgbench -i command). We * could fix that by giving them non-nulldefault values. * However, that would completely break comparability of pgbench * results with prior versions. Since pgbench has never pretended * to be fully TPC-B compliant anyway, we stick with the * historical behavior. -- Tatsuo Ishii SRA OSS, Inc. Japan
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