Practice — Database Indexing (6 questions)
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One Index, and Write Throughput Craters Anyway Permalink →
A Postgres user_sessions table has exactly one index: a B-tree
on last_active_at, which is updated on essentially every request.
Write throughput is far worse than "one extra index write per update"
would suggest, and table bloat / autovacuum load is unusually high —
for a table with only a single index.
Beyond simple write-count scaling with the number of indexes, what's actually happening?
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