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Joins work; it is their speed that is unmeasured (#402 follow-up) #404

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jdatcmd merged 2 commits into from
Aug 4, 2026
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Joins work; it is their speed that is unmeasured (#402 follow-up) #404

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docs: joins work; it is their speed that is unmeasured (#402 follow-up)
jdatcmd Aug 4, 2026
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docs: split the joins sentence to the 25-word STE limit
jdatcmd Aug 4, 2026
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6 changes: 6 additions & 0 deletions docs/benchmarks.md
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Expand Up @@ -625,6 +625,12 @@ to dimensions, and the selective-dimension-join pattern. Those are a large part
what columnar storage is usually bought for, and this page says nothing about
them. Not that we do badly on them. We have not measured them. See #401.

Joins themselves work. A columnar table joins a heap table in either direction,
and joins another columnar table. Hash, merge and nested-loop strategies all return
the same rows as the all-heap equivalent. Column projection survives the join, so
the columnar side reads only the columns the join and the target list need. What is
absent is a measurement of how fast that is, not evidence that it works.

Read the conclusions below as being about single-table scan and aggregate work,
because that is the evidence behind them.

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