菜单
VelociDB Change Data Capture - the in-memory change log in src/cdc.rs and its executor hooks. Use when modifying cdc.rs, adding CDC hooks to new write paths, changing ChangeEvent fields, or debugging missing/duplicate/out-of-order change events.
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基于 SOC 职业分类
How VelociDB's async API and parallel query execution work - the tokio spawn_blocking model in src/async_api.rs and the rayon thresholds in the executor. Use when modifying async_api.rs, adding async methods, tuning parallelism, or debugging blocked runtimes, stalled futures, or async test hangs.
How to run and write VelociDB tests - test suite layout, commands, and patterns for unit, integration, crash-recovery, property-based, and async tests. Use when adding features, fixing bugs, writing new tests, or deciding which suites must pass before a change is done.
VelociDB vector search implementation - F32_BLOB(n)/VECTOR(n) columns, vector32 literals, distance functions, and exact parallel KNN. Use when modifying src/vector.rs, adding distance metrics, extending vector SQL syntax, or debugging dimension-mismatch, KNN-ordering, or vector-parsing issues.
VelociDB code conventions - error handling, module boundaries, the experimental-modules policy, locking style, and documentation expectations. Use when writing or reviewing any VelociDB code, deciding where new code lives, or cleaning up warnings.
Debugging VelociDB - REPL-based reproduction, tracing, inspecting db/WAL files, and a map of common failure modes to their causes. Use when investigating bugs, corruption errors, deadlocks/hangs, wrong query results, or data that disappears after reopen.
Extending VelociDB's regex-based SQL parser in src/parser.rs - statement dispatch, quote/paren-aware splitting helpers, value parsing, and known fragility. Use when adding SQL syntax, new statements or operators, changing WHERE/ORDER BY/VALUES parsing, or debugging "Invalid ... syntax" / mis-split errors.
| name | cdc |
| description | VelociDB Change Data Capture - the in-memory change log in src/cdc.rs and its executor hooks. Use when modifying cdc.rs, adding CDC hooks to new write paths, changing ChangeEvent fields, or debugging missing/duplicate/out-of-order change events. |
Turso-inspired real-time change tracking. Opt-in, in-memory, bounded.
src/cdc.rs)CdcManager holds a VecDeque<ChangeEvent> behind a parking_lot::RwLock,
a monotonic AtomicU64 sequence counter (starts at 1), and an enabled flag.DEFAULT_CDC_CAPACITY = 65_536); oldest events are
dropped when full. Consumers detect gaps by comparing sequence numbers.disable() also clears the log.ChangeEvent: seq, table, op (Insert/Update/Delete), rowid
(primary key), before: Option<Row>, after: Option<Row>.
Insert has no before; Delete has no after.
Database::{enable_cdc, disable_cdc, cdc_enabled, changes_since(seq), cdc_latest_seq}AsyncConnection::changes_since(seq).await.cdc on|off, .changes [seq]One Arc<CdcManager> lives on Database and is passed into Executor::new.
Hooks exist in execute_insert, execute_update, execute_delete in
src/executor.rs. When adding a hook to a new write path:
cdc_events into a local Vec inside the B-tree block and call
cdc.record(...) only after the result is Ok — a failed statement's
pages are rolled back by abort_group, so recording early would emit
phantom events.self.cdc.is_enabled() to keep the disabled
path zero-cost.rowid is the OLD key; the new key is
visible in after.Unit tests in src/cdc.rs (disabled-by-default, ordering, capacity bound);
end-to-end in tests/advanced_features_tests.rs::test_cdc_capture_and_poll
(asserts op sequence, before/after images, incremental polling).