filesystem or a database system • Available state backends in Flink: • In-memory • File system • RocksDB State backends 7 Vasiliki Kalavri | Boston University 2020 MemoryStateBackend • Stores state Vasiliki Kalavri | Boston University 2020 RocksDBStateBackend • Stores all state into embedded RocksDB instances • Accesses require de/serialization • Checkpoints state to a remote file system and supports Kalavri | Boston University 2020 RocksDB 10 RocksDB is an LSM-tree storage engine with key/value interface, where keys and values are arbitrary byte streams. https://rocksdb.org/ https://www.ververica

e-1.7/ops/config.html#configuring-the-network-buffers 8 https://www.da-platform.com/blog/manage-rocksdb-memory-size-apache-flink? __hstc=216506377.c9dc814ddd168ffc714fc8d2bf20623f. 1550652804788.1550652804788 particularly important, when using the RocksDB statebackend, since RocksDB allocates a considerable amount of memory off heap. To understand how much memory RocksDB might use, you can checkout this blog

automatically checkpointed and restored • vertically scalable: Flink state can be kept in embedded RocksDB instances that scale by adding more local disk • horizontally scalable: Flink state is redistributed

• How to represent the spanner? As an adjacency list? which state primitives are suitable? Is RocksDB a suitable backend for graph state? • How to compute the distance between edges? Do we need to

to checkpoint? Do we need to checkpoint the complete application state in every checkpoint? • RocksDB supports both asynchronous and incremental checkpoints: • take a local snapshot and use a background