Struct ColumnarCache 

pub struct ColumnarCache { /* private fields */ }

Tier 2: Columnar cache for OLAP queries

Implementations

impl ColumnarCache

pub fn new() -> Self

Create a new Columnar Cache with default memory limit (1GB).

pub fn with_memory_limit(max_memory: usize) -> Self

Create a new Columnar Cache with custom memory limit.

pub fn memory_usage(&self) -> usize

Get current memory usage in bytes.

pub fn memory_limit(&self) -> usize

Get memory limit in bytes.

pub fn should_evict(&self) -> bool

Check if cache should evict entries.

pub fn persist_to_disk(&self, table: &str, cache_dir: &str) -> DbxResult<()>

Persist table cache to disk using Arrow IPC format

Performance

• Eliminates JSON parsing on restart (50-70% faster)
• Zero-copy deserialization

pub fn load_from_disk( &self, table: &str, cache_dir: &str, ) -> DbxResult<Vec<RecordBatch>>

Load table cache from disk using Arrow IPC format

Performance

• ~0.5µs per batch (vs JSON: ~10µs)
• Zero-copy: direct memory mapping

pub fn clear_disk_cache(&self, table: &str, cache_dir: &str) -> DbxResult<()>

Clear persisted cache files for a table

pub fn insert_batch(&self, table: &str, batch: RecordBatch) -> DbxResult<()>

Insert a RecordBatch into the cache as Raw (Binary) data.

pub fn sync_from_storage( &self, table: &str, rows: Vec<(Vec<u8>, Vec<u8>)>, table_schema: Option<SchemaRef>, ) -> DbxResult<usize>

Sync data from storage tiers to Columnar Cache.

If table_schema is provided, converts data to typed format (SQL table). Otherwise, stores as raw Binary format (CRUD data).

pub fn get_batches_with_filter<F>( &self, table: &str, projection: Option<&[usize]>, filter: F, ) -> DbxResult<Option<Vec<RecordBatch>>>

where F: Fn(&RecordBatch) -> DbxResult<BooleanArray>,

Get batches with filter pushdown.

The filter closure takes a full RecordBatch and returns a BooleanArray (mask). Rows where mask is true are kept.

pub fn get_batches( &self, table: &str, projection: Option<&[usize]>, ) -> DbxResult<Option<Vec<RecordBatch>>>

Get all batches for a table with optional column projection.

pub fn clear_table(&self, table: &str) -> DbxResult<()>

Clear all cached data for a table.

pub fn clear_all(&self) -> DbxResult<()>

Clear all cached data.

pub fn get_schema(&self, table: &str) -> Option<SchemaRef>

Get schema for a table.

pub fn table_names(&self) -> Vec<String>

Get list of cached tables.

pub fn has_table(&self, table: &str) -> bool

Check if a table exists in the cache.

Trait Implementations

impl Default for ColumnarCache

fn default() -> Self

Returns the “default value” for a type.