Add lesson 30: Index types beyond B-tree#89
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Part of #6 Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
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…t scale Grows docs from ~40k to ~5,000,000 rows (seed-once base branch). At that size the old demos regressed to Seq Scans, so distributions were fixed so each index genuinely wins: rare 'gin' tag / 'report' kind (~1%), a rare 'pinned' key for the GIN ? existence demo (the old 'priority' key was on every row -> always a Seq Scan), ~50k distinct emails and ~500k owners. Moved the hash demo to email (a truer wide-key example) so the covering index is the sole owner_id index and yields a real Index Only Scan. No VACUUM (the seed runs as one implicit transaction; high owner cardinality gives the Index Only Scan instead). All 7 demos verified on Postgres 16. Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
query-returns check confirms the learner built the GIN index on tags via pg_indexes matching 'gin (tags' — robust to naming, ignores the meta GIN. Verified on PG16 (0 before, 1 after). Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
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Adds the third lesson of Module 7: Performance & indexing — index types beyond B-tree (roadmap item
30-index-types).What's in the lesson
Each with a when-to-use, a cost note, a
CREATE INDEX, and a query it accelerates:@>,?), arrays (@>,<@,&&),tsvector(@@)&&), spatial, KNN (<->), exclusion constraintscreated_at)CREATE INDEX … WHERE …… (lower(email))INCLUDEfor Index-Only Scanspg_trgmis mentioned only as an out-of-scope extension (the sandbox is core-only).Seed
A
docstable (~40k rows viagenerate_series) withjsonb,text[], a skewedstatus, mixed-caseemail, and time-orderedcreated_atso every index type is demonstrable; ends withANALYZE.Checks
One
query-returnscheck (tags-gin-created): confirms the learner built the GIN index ontagsby queryingpg_indexesfor a definition matchinggin (tags— robust to the index name and ignoring themetaGIN. Verified on PG16 (0 before, 1 after).Notes
Includes the byte-identical Module 7
module.yaml.npm run lessons:validateandnext buildboth pass.Part of #6
🤖 Generated with Claude Code