Struct OnDiskHashIndex 

pub struct OnDiskHashIndex<K: IndexKey> { /* private fields */ }

On-disk persistent hash index backed by the BufferManager.

Type Parameters

• K: The key type. Must implement IndexKey for serialization.

Thread Safety

This struct is Send + Sync when wrapped in Arc<Mutex<...>>.

Implementations

impl<K: IndexKey + Hash + Eq> OnDiskHashIndex<K>

pub fn new(file_name: &str) -> Self

Create a new on-disk hash index.

If bm is None, operates purely in-memory (L1 cache only). The file_name is used to register the index file with the BufferManager.

pub fn rebuild_from_disk(&mut self, bm: &mut BufferManager) -> Result<()>

Rebuild the L1 cache from on-disk pages.

Call this on database startup after the BufferManager is initialized.

pub fn len(&self) -> usize

Get the number of entries.

pub fn is_empty(&self) -> bool

pub fn lookup_cached(&self, key: &K) -> Option<u64>

Look up a key in the L1 cache (fast path).

For write operations during query execution, this is always used.

pub fn lookup(&self, key: &K, bm: &mut BufferManager) -> Result<Option<u64>>

Look up a key, potentially reading from the on-disk index.

If the key is in L1 cache, returns immediately. Otherwise, scans the on-disk bucket page.

pub fn insert(&mut self, key: K, value: u64)

Insert a key-value pair.

Writes to L1 cache immediately. The on-disk write happens on flush().

pub fn delete(&mut self, key: &K)

Delete a key.

pub fn flush(&mut self, bm: &mut BufferManager) -> Result<()>

Flush all cached entries to the on-disk hash index.

This writes all key-value pairs from L1 cache into the BufferManager page-structured hash table. After this, the index is durably stored.

pub fn iter(&self) -> impl Iterator<Item = (&K, &u64)>

Iterate over all cached entries.

Trait Implementations

impl<K: Debug + IndexKey> Debug for OnDiskHashIndex<K>

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

Formats the value using the given formatter.

impl<K: IndexKey + Hash + Eq> Default for OnDiskHashIndex<K>

fn default() -> Self

Returns the “default value” for a type.