Struct ColumnarCache 

pub struct ColumnarCache { /* private fields */ }

LRU cache for columnar table representations

Provides memory-bounded caching of columnar table data with automatic eviction when the memory budget is exceeded. Tables are stored as Arc to enable zero-copy sharing between queries.

Memory Management

The cache tracks memory usage based on ColumnarTable::size_in_bytes(). When inserting a new entry would exceed the budget, the least recently used entries are evicted until there’s sufficient space.

Example

use vibesql_storage::columnar_cache::ColumnarCache;

// Create a cache with 256MB budget
let cache = ColumnarCache::new(256 * 1024 * 1024);

// Get or create columnar representation
if let Some(columnar) = cache.get("lineitem") {
    // Use cached data
} else {
    // Convert and cache
    let columnar = table.scan_columnar()?;
    cache.insert("lineitem", columnar);
}

Implementations

impl ColumnarCache

pub fn new(max_memory: usize) -> Self

Create a new columnar cache with the specified memory budget

Arguments

• max_memory - Maximum memory budget in bytes

Example

// 256MB cache
let cache = ColumnarCache::new(256 * 1024 * 1024);

pub fn get(&self, table_name: &str) -> Option<Arc<ColumnarTable>>

Get a cached columnar table representation

Returns Some(Arc<ColumnarTable>) if the table is cached, None otherwise. Accessing a cached entry marks it as recently used. Table names are normalized for case-insensitive matching.

pub fn insert( &self, table_name: &str, columnar: ColumnarTable, ) -> Arc<ColumnarTable>

Insert or update a columnar table in the cache

If the table is already cached, the existing entry is updated. If inserting would exceed the memory budget, least recently used entries are evicted until there’s sufficient space. Table names are normalized for case-insensitive matching.

Arguments

• table_name - Name of the table
• columnar - The columnar table data to cache

Returns

The Arc-wrapped columnar table (for immediate use)

pub fn invalidate(&self, table_name: &str)

Invalidate a cached table entry

Called when a table is modified (INSERT/UPDATE/DELETE) to ensure the cache doesn’t serve stale data. Table names are normalized for case-insensitive matching.

pub fn clear(&self)

Clear all cached entries

pub fn stats(&self) -> CacheStats

Get cache statistics

pub fn memory_usage(&self) -> usize

Get current memory usage in bytes

pub fn max_memory(&self) -> usize

Get the memory budget in bytes

pub fn len(&self) -> usize

Get the number of cached tables

pub fn is_empty(&self) -> bool

Check if the cache is empty

pub fn contains(&self, table_name: &str) -> bool

Check if a table is cached Table names are normalized for case-insensitive matching.

Trait Implementations

impl Clone for ColumnarCache

fn clone(&self) -> Self

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for ColumnarCache

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.