FahdShalhoub
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18 lines
995 B
SQL
18 lines
995 B
SQL
-- Browsing the catalogue, and paging through it.
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--
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-- Every search orders by (rank, created_at, id). When there is no title term
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-- the rank is a constant, and Postgres folds a constant sort key away — so the
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-- order that remains is exactly this index, and a browse becomes an index-only
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-- scan that stops as soon as the page is full instead of sorting the table.
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--
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-- Measured at 200k rows: a first page of a browse goes from a 15 ms parallel
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-- sequential scan with a top-N sort to 0.03 ms. It matters more for the cursor
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-- than for the first page — the keyset comparison (created_at, id) < (…)
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-- becomes an index condition rather than a filter, so a deep page is a seek
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-- to the right place in the index rather than a walk through everything
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-- before it.
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--
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-- DESC on both columns to match the ORDER BY: a btree can be read backwards,
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-- but only as a whole, so a mixed-direction ordering could not use it.
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CREATE INDEX videos_recent_idx ON videos (created_at DESC, id DESC);
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