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While discussing comment improvements (see next commit) by Justin Pryzby, Tom complained about a few details of the logic to infer the length of the NULL bitmap when building the JITed tuple deforming function. That bitmap allows to avoid checking the tuple header's natts, a check which often causes a pipeline stall Improvements: a) As long as missing columns aren't taken into account, we can continue to infer the length of the NULL bitmap from NOT NULL columns following it. Previously we stopped at the first missing column. It's unlikely to matter much in practice, but the alternative would have been to document why we stop. b) For robustness reasons it seems better to also check against attisdropped - RemoveAttributeById() sets attnotnull to false, but an additional check is trivial. c) Improve related comments Discussion: https://postgr.es/m/20637.1555957068@sss.pgh.pa.us Backpatch: -
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