mirror of
https://github.com/coder/coder.git
synced 2026-10-31 02:43:21 +08:00
Garrett Delfosse
378ac91b49
Chat message search used the `simple` text search config, which folds case but does no stemming, so `refactor` did not match messages containing `refactoring`. Message bodies now index and query with the `english` config, which stems both sides. Titles, PR titles, and all other filters are unchanged. Migration `000585` adds a `chat_messages.search_tsv_config` enum column recording which config produced each stored vector and stamps existing vectors `'simple'` (a column-only update; vectors and indexes are untouched, since rewriting `search_tsv` would block message writes on large tables). The dbpurge sweep gains a bounded `ReindexStaleChatMessagesSearchTsv` pass that rewrites stale vectors newest first and stops for the process lifetime once drained. Until a row is rewritten, `GetChats` matches it with the config that produced it, so pre-migration exact-form searches keep working during the drain. Vectors written by old binaries mid rolling upgrade cannot stamp the config, stay pending, and self-heal on the next upgraded sweep. Steady-state DB load is unchanged. The down migration resets `english` vectors to `NULL` so the parent version's existing sweep rewrites them with `simple`. Closes [CODAGT-867](https://linear.app/codercom/issue/CODAGT-867/backend-search-improvements-to-handle-partial-matches) <details> <summary>Decision log</summary> - **`english` stemming over prefix matching.** On a 300k-row corpus a stemmed lookup is a single GIN entry-tree probe, while `term:*` prefix matching unions posting lists of every lexeme sharing the prefix (up to a full scan for short prefixes), is asymmetric, and loses the `websearch_to_tsquery` phrase/OR/negation UX. `pg_trgm` rejected as a heavier index with different semantics. - **Scope to message bodies only** (review). Titles and PR titles keep their `simple` FTS expressions and indexes, identical to main. - **Config-versioned queue over migration-time reset** (review). An unqualified `UPDATE ... SET search_tsv = NULL` rewrites every indexed row in the migration transaction, and an old replica could backfill reset rows with `simple` vectors that permanently leave the `search_tsv IS NULL` queue. The config column makes staleness explicit and both problems disappear. - **Enum over `text`** (review) for the config column. - **Trade-offs.** English stopwords are dropped from message search (stopword-only queries match no messages); stemming is English-specific; titles do not stem; prefix matching remains out of scope. </details> --- 🤖 This PR was generated by Coder Agents on behalf of @f0ssel.