Key | Default | Type | Description
--- | --- | --- | ---
##### state.backend.rocksdb.block.blocksize | 4 kb | MemorySize | The approximate size (in bytes) of user data packed per block. The default blocksize is '4KB'.
##### state.backend.rocksdb.block.cache-size | 8 mb | MemorySize | The amount of the cache for data blocks in RocksDB. The default block-cache size is '8MB'.
##### state.backend.rocksdb.block.metadata-blocksize | 4 kb | MemorySize | Approximate size of partitioned metadata packed per block. Currently applied to indexes block when partitioned index/filters option is enabled. The default blocksize is '4KB'.
##### state.backend.rocksdb.bloom-filter.bits-per-key | 10.0 | Double | Bits per key that bloom filter will use, this only take effect when bloom filter is used. The default value is 10.0.
##### state.backend.rocksdb.bloom-filter.block-based-mode | false | Boolean | If true, RocksDB will use block-based filter instead of full filter, this only take effect when bloom filter is used. The default value is 'false'.
##### state.backend.rocksdb.compaction.level.max-size-level-base | 256 mb | MemorySize | The upper-bound of the total size of level base files in bytes. The default value is '256MB'.
##### state.backend.rocksdb.compaction.level.target-file-size-base | 64 mb | MemorySize | The target file size for compaction, which determines a level-1 file size. The default value is '64MB'.
##### state.backend.rocksdb.compaction.level.use-dynamic-size | false | Boolean | If true, RocksDB will pick target size of each level dynamically. From an empty DB, RocksDB would make last level the base level, which means merging L0 data into the last level, until it exceeds max_bytes_for_level_base. And then repeat this process for second last level and so on. The default value is 'false'. For more information, please refer to RocksDB's doc.
##### state.backend.rocksdb.compaction.style | LEVEL | Enum | The specified compaction style for DB. Candidate compaction style is LEVEL, FIFO, UNIVERSAL or NONE, and Flink chooses 'LEVEL' as default style. Possible values: "LEVEL" "UNIVERSAL" "FIFO" "NONE"
##### state.backend.rocksdb.files.open | -1 | Integer | The maximum number of open files (per stateful operator) that can be used by the DB, '-1' means no limit. The default value is '-1'.
##### state.backend.rocksdb.log.dir | (none) | String | The directory for RocksDB's information logging files. If empty (Flink default setting), log files will be in the same directory as the Flink log. If non-empty, this directory will be used and the data directory's absolute path will be used as the prefix of the log file name. If setting this option as a non-existing location, e.g '/dev/null', RocksDB will then create the log under its own database folder as before.
##### state.backend.rocksdb.log.file-num | 4 | Integer | The maximum number of files RocksDB should keep for information logging (Default setting: 4).
##### state.backend.rocksdb.log.level | INFO_LEVEL | Enum | The specified information logging level for RocksDB. If unset, Flink will use `INFO_LEVEL`. Note: RocksDB info logs will not be written to the TaskManager logs and there is no rolling strategy, unless you configure `state.backend.rocksdb.log.dir`, `state.backend.rocksdb.log.max-file-size`, and `state.backend.rocksdb.log.file-num` accordingly. Without a rolling strategy, long-running tasks may lead to uncontrolled disk space usage if configured with increased log levels! There is no need to modify the RocksDB log level, unless for troubleshooting RocksDB. Possible values: "DEBUG_LEVEL" "INFO_LEVEL" "WARN_LEVEL" "ERROR_LEVEL" "FATAL_LEVEL" "HEADER_LEVEL" "NUM_INFO_LOG_LEVELS"
##### state.backend.rocksdb.log.max-file-size | 25 mb | MemorySize | The maximum size of RocksDB's file used for information logging. If the log files becomes larger than this, a new file will be created. If 0, all logs will be written to one log file. The default maximum file size is '25MB'.
##### state.backend.rocksdb.restore-overlap-fraction-threshold | 0.0 | Double | The threshold of overlap fraction between the handle's key-group range and target key-group range. When restore base DB, only the handle which overlap fraction greater than or equal to threshold has a chance to be an initial handle. The default value is 0.0, there is always a handle will be selected for initialization.
##### state.backend.rocksdb.thread.num | 2 | Integer | The maximum number of concurrent background flush and compaction jobs (per stateful operator). The default value is '2'.
##### state.backend.rocksdb.use-bloom-filter | false | Boolean | If true, every newly created SST file will contain a Bloom filter. It is disabled by default.
##### state.backend.rocksdb.write-batch-size | 2 mb | MemorySize | The max size of the consumed memory for RocksDB batch write, will flush just based on item count if this config set to 0.
##### state.backend.rocksdb.writebuffer.count | 2 | Integer | The maximum number of write buffers that are built up in memory. The default value is '2'.
##### state.backend.rocksdb.writebuffer.number-to-merge | 1 | Integer | The minimum number of write buffers that will be merged together before writing to storage. The default value is '1'.
##### state.backend.rocksdb.writebuffer.size | 64 mb | MemorySize | The amount of data built up in memory (backed by an unsorted log on disk) before converting to a sorted on-disk files. The default writebuffer size is '64MB'.