Module memory_pool 

Hierarchical MemoryPool for query execution.

Replaces the flat per-query MemoryBudget with a multi-level tree:

DatabaseMemoryPool (process-level, admission control)
  → QueryPool       (per-query slice)
    → FragmentPool   (per-fragment within query)
      → OperatorPool  (per-operator within fragment)
        → TaskPool     (per-task within operator)

All reservations use RAII guards. The database pool enforces a global admission limit so that no single query can exhaust memory for the entire process.

Structs

DatabaseMemoryPool

Process-level memory pool with admission control.

FragmentPool

Per-fragment memory pool, allocated from QueryPool.

MemoryPoolReservation

RAII guard that releases reserved memory on drop.

OperatorPool

Per-operator memory pool, allocated from FragmentPool.

PoolHandle

Clonable handle that shares the same pool account.

PooledChunk

A DataChunk with an attached MemoryPoolReservation.

QueryPool

Per-query memory pool, allocated from DatabaseMemoryPool.

TaskPool

Per-task memory pool, allocated from OperatorPool.

Enums

MemoryPoolError

Error type for memory pool operations.