Module mz_adapter::coord::catalog_oracle

A timestamp oracle that relies on the Catalog for persistence/durability and reserves ranges of timestamps.

Structs

• CatalogTimestampOracle
  A type that wraps a InMemoryTimestampOracle and provides durable timestamps. This allows us to recover a timestamp that is larger than all previous timestamps on restart. The protocol is based on timestamp recovery from Percolator https://research.google/pubs/pub36726/. We “pre-allocate” a group of timestamps at once, and only durably store the largest of those timestamps. All timestamps within that interval can be served directly from memory, without going to disk. On restart, we re-initialize the current timestamp to a value one larger than the persisted timestamp.
• CatalogTimestampPersistence 🔒
  A TimestampPersistence that is backed by a Catalog.
• InMemoryTimestampOracle
  A type that provides write and read timestamps, reads observe exactly their preceding writes.

Constants

• TIMESTAMP_INTERVAL_UPPER_BOUND
  The Coordinator tries to prevent the persisted timestamp from exceeding a value TIMESTAMP_INTERVAL_UPPER_BOUND times TIMESTAMP_PERSIST_INTERVAL larger than the current system time.

Statics

• TIMESTAMP_PERSIST_INTERVAL
  Interval used to persist durable timestamps. See CatalogTimestampOracle for more details.

Traits

• TimestampPersistence
  Provides persistence of timestamps for CatalogTimestampOracle.

Functions

• monotonic_now 🔒
  Returns the current system time while protecting against backwards time jumps.
• upper_bound 🔒
  Convenience function for calculating the current upper bound that we want to prevent the global timestamp from exceeding.