Configuration Items

The parameter configuration rules for the Log, StateStore, and Metric modules of OmniStateStore cover log management, state storage, and performance monitoring, providing guidance for deploying and tuning OmniStateStore on Flink.

Table 1, Table 2, and Table 3 describe the configuration items of the Log, StateStore, and Metric modules.

**Table 1** Configuration items of the Log module
Configuration Item	Description	Default Value	Value Range	Remarks
state.backend.ockdb.jni.logfile	Log file path and name.	/usr/local/flink/log/kv.log	Files in the path on which the Flink run user has the read and write permissions (The path must exist.)	Check that the path exists and the Flink run user has the read and write permissions on the path.
state.backend.ockdb.jni.loglevel	Log level. 1: DEBUG 2: INFO 3: WARN 4: ERROR	2	[1, 4]	None
state.backend.ockdb.jni.lognum	Maximum number of log files.	20	[10, 50]	None
state.backend.ockdb.jni.logsize	Size of a single log file. Unit: MB.	20	[10, 50]	None

**Table 2** Configuration items of the StateStore module
Configuration Item	Description	Default Value	Value Range	Remarks
state.backend	Open source Flink parameter, which is used to configure the state backend.	None	com.huawei.ock.bss.OckDBStateBackendFactory	Ensure that the case-sensitive characters are correctly spelled.
state.backend.ockdb.localdir	Local OmniStateStore data path.	None	An existing path for which the Flink run user has the read and write permissions.	Check that the path exists and the Flink run user has the read and write permissions on the path. Check that the path and the taskmanager.state.local.root-dirs path are in the same file system.
taskmanager.state.local.root-dirs	Open-source Flink parameter, which is used to set the local checkpoint temporary directory.	None	An existing path for which the Flink run user has the read and write permissions.	You are recommended to set this configuration item. If you choose not to set this configuration item, the path specified by io.tmp.dirs is used by default. Check that the path and the state.backend.ockdb.localdir path are in the same file system.
state.backend.ockdb.savepoint.sort.local.dir	Path for storing temporary sorting files generated during savepoint creation. This parameter is required for using savepoints.	/usr/local/flink/savepoint/tmp	An existing path for which the Flink run user has the read and write permissions.	Check that the path exists and the Flink run user has the read and write permissions on the path.
state.backend.ockdb.jni.slice.watermark.ratio	The cache layer triggers data eviction by setting the high and low watermark ratio thresholds. Cold data is migrated to the LSM file storage layer based on the preset policy to dynamically balance storage resources.	0.8	(0, 1)	Generally, you do not need to set it separately.
state.backend.ockdb.file.memory.fraction	Ratio of the memory cache space used for reading and writing data at the LSM layer to the maximum memory of the entire database instance.	0.2	[0.1, 0.5]	Generally, you do not need to set it separately.
state.backend.ockdb.jni.lsmstore.compaction.switch	Indicates whether to sort and merge data in the LSM file storage layer. The leveled compaction mechanism of the LSM file storage layer controls the sorting and compaction of data files to optimize storage performance and space utilization.	1	0: disable 1: enable	It is recommended that you enable this option.
state.backend.ockdb.ttl.filter.switch	Compresses time to live (TTL) expired data in the background.	false	false: disable true: enable	You are advised to enable this function for TTL State.
state.backend.ockdb.lsmstore.compression.policy	Compression policy of each level in the LSM store. It is used with the default value of "state.backend.ockdb.lsmstore.compression.level.policy". level0: Compression is disabled. level1: Compression is disabled. level2: LZ4 compression is enabled. Other levels: Full compression is enabled.	lz4	none: Compression is disabled. lz4: LZ4 compression is enabled.	If the checkpoint file to be uploaded is too large, you are advised to enable this function.
state.backend.ockdb.lsmstore.compression.level.policy	Configures the LSM file compression policy for different levels. The default value is none,none,lz4, which indicates that compression is disabled at level 0 and level 1 and LZ4 compression is enabled at level 2.	none,none,lz4	none: Compression is disabled. lz4: LZ4 compression is enabled.	When checkpoints become a bottleneck, you can advance the compression policy to a lower level. The default level range is [0, 5]. level0 indicates foreground write compression. None is recommended. Other levels indicate background compression.
state.backend.ockdb.lazy.download.switch	Indicates whether to enable lazy loading during recovery from a checkpoint.	false	false: disable true: enable	When the checkpoint size is large, enable this option to shorten the time required for restoring a task to the running state.
state.backend.ockdb.bloom.filter.switch	Enables or disables the Bloom filter for status keys.	true	false: disable true: enable	You are advised to enable this function in scenarios where a large number of invalid key accesses. When this function is enabled, the memory usage increases by dozens of megabytes.
state.backend.bloom.filter.expected.key.count	Order of magnitude of keys to be filtered by the Bloom filter in a single state.	8000000	[1000000, 10000000]	Generally, you do not need to set it separately. A larger value indicates that the Bloom filter occupies more memory.
state.backend.ockdb.cache.filter.and.index.switch	Enables or disables the use of the least recently used (LRU) cache for filter and index blocks at the LSM layer.	true	false: disable true: enable	Generally, you do not need to set it separately. If there are a large number of files and different files are frequently read, you are advised to enable this function.
state.backend.ockdb.cache.filter.and.index.ratio	Ratio of the memory occupied by the filter and index blocks to the total memory. This memory is not subject to LRU-based eviction.	0	(0, 1)	Generally, you do not need to set it separately. You are advised to enable this function when the filter and index blocks are frequently released in the cache due to heavy pressure.
state.backend.ockdb.checkpoint.backup	Directory for storing local checkpoint backup slice files when local restoration is enabled.	None	Files in the path on which the Flink run user has the read and write permissions (The path must exist.)	Set this parameter when local restoration is enabled. Check that the path exists and the Flink run user has the read and write permissions on the path.
state.backend.ockdb.timer-service.factory	Location where the Flink timer is stored.	OCKDB	OCKDB: persistently stored in the state backend HEAP: stored in the JVM heap memory	When the number of timers is small, the heap-based timer may have better performance.
state.backend.ockdb.kv-separate.switch	Enables or disables KV separation.	false	false: disable true: enable	Enable KV separation if this value is large.
state.backend.ockdb.kv-separate.threshold	Threshold for enabling KV separation. Enable KV separation when this value is exceeded.	200	(8, 4294967295)	Values greater than this threshold are stored separately after KV separation.

**Table 3** Configuration items of the Metric module
Configuration Item	Description	Default Value	Value Range	Remarks
state.backend.ockdb.metric.enable	Enables or disables the overall metric function. OmniStateStore collects metric information after this function is enabled.	false	false: disable true: enable	The metric function of each module takes effect only after this option is enabled.
state.backend.ockdb.metric.memory	Enables or disables the metric function of the MemoryManager module.	false	false: disable true: enable	None
state.backend.ockdb.metric.fresh.table	Enables or disables the metric function of the FreshTable module.	false	false: disable true: enable	None
state.backend.ockdb.metric.slice.table	Enables or disables the metric function of the SliceTable module.	false	false: disable true: enable	None
state.backend.ockdb.metric.lsm.store	Enables or disables the metric function of the LSM Store module.	false	false: disable true: enable	None
state.backend.ockdb.metric.lsm.cache	Enables or disables the metric function of the LSM Cache module.	false	false: disable true: enable	None
state.backend.ockdb.metric.snapshot	Enables or disables the metric function of the Snapshot module.	false	false: disable true: enable	None
state.backend.ockdb.metric.restore	Enables or disables the metric function of the Restore module.	false	false: disable true: enable	None

Parent topic: References