Re: [PoC] Improve dead tuple storage for lazy vacuum

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От John Naylor
Тема Re: [PoC] Improve dead tuple storage for lazy vacuum
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Msg-id CAFBsxsHWX3vPGtuom5=p=Ve4NM3H9Pa5eYL3-ys+DUH4ZoxDmA@mail.gmail.com
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Ответ на Re: [PoC] Improve dead tuple storage for lazy vacuum  (John Naylor <john.naylor@enterprisedb.com>)
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I wrote:

> I see. IIUC from a brief re-reading of the code, saving that chunk would only save us from re-loading "parent->shift" from L1 cache and shifting the key. The cycles spent doing that seem small compared to the rest of the work involved in growing a node. Expressions like "if (idx < 0) return false;" return to an asserts-only variable, so in production builds, I would hope that branch gets elided (I haven't checked).

On further reflection, this is completely false and I'm not sure what I was thinking. However, for the update-inner case maybe we can assert that we found a valid slot.

--
John Naylor
EDB: http://www.enterprisedb.com

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