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# Metrics and Monitoring Options
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The RocksDB State Backend provides comprehensive metrics integration that forwards RocksDB native metrics to Flink's metrics system. This enables detailed monitoring of performance, memory usage, and operational health.
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## Core Imports
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```java { .api }
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import org.apache.flink.state.rocksdb.RocksDBNativeMetricOptions;
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import org.apache.flink.state.rocksdb.RocksDBProperty;
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import org.apache.flink.configuration.ConfigOption;
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import org.apache.flink.configuration.ReadableConfig;
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import org.apache.flink.configuration.Configuration;
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import java.util.Set;
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import java.util.Collection;
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```
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## RocksDBNativeMetricOptions Class
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### Class Definition
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```java { .api }
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@PublicEvolving
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public class RocksDBNativeMetricOptions {
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    // Configuration for enabling RocksDB native metrics forwarding to Flink's metrics reporter
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}
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```
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### Factory Method
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```java { .api }
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public static RocksDBNativeMetricOptions fromConfig(ReadableConfig config)
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```
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Creates RocksDBNativeMetricOptions from configuration.
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**Parameters:**
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- `config` - Configuration containing metric settings
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**Returns:** Configured RocksDBNativeMetricOptions instance
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**Example:**
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```java
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Configuration config = new Configuration();
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config.set(RocksDBNativeMetricOptions.MONITOR_BLOCK_CACHE_HIT, true);
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config.set(RocksDBNativeMetricOptions.ESTIMATE_NUM_KEYS, true);
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RocksDBNativeMetricOptions metricOptions = RocksDBNativeMetricOptions.fromConfig(config);
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```
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## Property-Based Metrics Configuration
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### Memory Table Metrics
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```java { .api }
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public static final ConfigOption<Boolean> MONITOR_NUM_IMMUTABLE_MEM_TABLES
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```
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Monitors the number of immutable memtables that have not yet been flushed.
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```java { .api }
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public static final ConfigOption<Boolean> MONITOR_MEM_TABLE_FLUSH_PENDING  
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```
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Monitors whether a memtable flush is pending.
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```java { .api }
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public static final ConfigOption<Boolean> MONITOR_CUR_SIZE_ACTIVE_MEM_TABLE
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```
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Monitors the approximate size of the active memtable in bytes.
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```java { .api }
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public static final ConfigOption<Boolean> MONITOR_CUR_SIZE_ALL_MEM_TABLE
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```
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Monitors the approximate size of all memtables in bytes.
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```java { .api }
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public static final ConfigOption<Boolean> MONITOR_SIZE_ALL_MEM_TABLES
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```
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Monitors the total size of all memtables in bytes.
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```java { .api }
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public static final ConfigOption<Boolean> MONITOR_NUM_ENTRIES_ACTIVE_MEM_TABLE
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```
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Monitors the total number of entries in the active memtable.
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```java { .api }
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public static final ConfigOption<Boolean> MONITOR_NUM_ENTRIES_IMM_MEM_TABLES
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```
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Monitors the total number of entries in the unflushed immutable memtables.
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```java { .api }
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public static final ConfigOption<Boolean> MONITOR_NUM_DELETES_ACTIVE_MEM_TABLE
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```
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Monitors the total number of delete entries in the active memtable.
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```java { .api }
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public static final ConfigOption<Boolean> MONITOR_NUM_DELETES_IMM_MEM_TABLE
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```
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Monitors the total number of delete entries in the unflushed immutable memtables.
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### Compaction and Background Process Metrics
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```java { .api }
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public static final ConfigOption<Boolean> TRACK_COMPACTION_PENDING
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```
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Monitors whether at least one compaction is pending.
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```java { .api }
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public static final ConfigOption<Boolean> MONITOR_BACKGROUND_ERRORS
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```
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Monitors the number of background errors encountered.
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```java { .api }
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public static final ConfigOption<Boolean> MONITOR_NUM_RUNNING_COMPACTIONS
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```
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Monitors the number of currently running compactions.
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```java { .api }
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public static final ConfigOption<Boolean> MONITOR_NUM_RUNNING_FLUSHES
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```
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Monitors the number of currently running flushes.
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```java { .api }
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public static final ConfigOption<Boolean> ESTIMATE_PENDING_COMPACTION_BYTES
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```
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Estimates the total bytes of files pending compaction.
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### Database Size and Key Metrics
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```java { .api }
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public static final ConfigOption<Boolean> ESTIMATE_NUM_KEYS
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```
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Estimates the number of keys in the RocksDB instance.
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```java { .api }
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public static final ConfigOption<Boolean> ESTIMATE_LIVE_DATA_SIZE
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```
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Estimates the size of live data in bytes.
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```java { .api }
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public static final ConfigOption<Boolean> MONITOR_TOTAL_SST_FILES_SIZE
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```
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Monitors the total size of all SST files in bytes.
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```java { .api }
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public static final ConfigOption<Boolean> MONITOR_LIVE_SST_FILES_SIZE
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```
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Monitors the total size of live SST files in bytes.
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### Memory and Cache Metrics
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```java { .api }
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public static final ConfigOption<Boolean> ESTIMATE_TABLE_READERS_MEM
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```
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Estimates the memory used by table readers.
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```java { .api }
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public static final ConfigOption<Boolean> BLOCK_CACHE_CAPACITY
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```
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Monitors the block cache capacity.
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```java { .api }
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public static final ConfigOption<Boolean> BLOCK_CACHE_USAGE
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```
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Monitors the memory size used by the block cache.
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```java { .api }
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public static final ConfigOption<Boolean> BLOCK_CACHE_PINNED_USAGE
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```
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Monitors the memory size used by pinned blocks in the block cache.
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### Snapshot and Version Metrics
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```java { .api }
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public static final ConfigOption<Boolean> MONITOR_NUM_SNAPSHOTS
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```
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Monitors the number of unreleased snapshots of the database.
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```java { .api }
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public static final ConfigOption<Boolean> MONITOR_NUM_LIVE_VERSIONS
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```
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Monitors the number of live versions (column family metadata).
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### Write Performance Metrics
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```java { .api }
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public static final ConfigOption<Boolean> MONITOR_ACTUAL_DELAYED_WRITE_RATE
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```
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Monitors the current actual delayed write rate.
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```java { .api }
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public static final ConfigOption<Boolean> IS_WRITE_STOPPED
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```
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Monitors whether writes have been stopped.
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### File Level Metrics
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```java { .api }
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public static final ConfigOption<Boolean> MONITOR_NUM_FILES_AT_LEVEL
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```
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Monitors the number of files at each level of the LSM tree.
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### Column Family Configuration
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```java { .api }
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public static final ConfigOption<Boolean> COLUMN_FAMILY_AS_VARIABLE
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```
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Exposes the column family name as a variable in metric names.
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## Statistics-Based Metrics Configuration  
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### Cache Performance Metrics
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```java { .api }
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public static final ConfigOption<Boolean> MONITOR_BLOCK_CACHE_HIT
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```
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Monitors the number of block cache hits.
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```java { .api }
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public static final ConfigOption<Boolean> MONITOR_BLOCK_CACHE_MISS
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```
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Monitors the number of block cache misses.
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### Bloom Filter Metrics
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```java { .api }
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public static final ConfigOption<Boolean> MONITOR_BLOOM_FILTER_USEFUL
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```
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Monitors the number of times bloom filter was useful in avoiding reads.
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```java { .api }
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public static final ConfigOption<Boolean> MONITOR_BLOOM_FILTER_FULL_POSITIVE
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```
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Monitors the number of times bloom filter gave a positive result.
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```java { .api }
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public static final ConfigOption<Boolean> MONITOR_BLOOM_FILTER_FULL_TRUE_POSITIVE
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```
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Monitors the number of times bloom filter gave a true positive result.
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### I/O Performance Metrics
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```java { .api }
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public static final ConfigOption<Boolean> MONITOR_BYTES_READ
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```
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Monitors the total number of bytes read.
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```java { .api }
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public static final ConfigOption<Boolean> MONITOR_ITER_BYTES_READ
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```
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Monitors the total number of bytes read by iterators.
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```java { .api }
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public static final ConfigOption<Boolean> MONITOR_BYTES_WRITTEN
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```
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Monitors the total number of bytes written.
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```java { .api }
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public static final ConfigOption<Boolean> MONITOR_COMPACTION_READ_BYTES
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```
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Monitors the total number of bytes read during compaction.
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```java { .api }
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public static final ConfigOption<Boolean> MONITOR_COMPACTION_WRITE_BYTES
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```
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Monitors the total number of bytes written during compaction.
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### Performance Degradation Metrics
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```java { .api }
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public static final ConfigOption<Boolean> MONITOR_STALL_MICROS
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```
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Monitors the total time spent in write stalls in microseconds.
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## Enable Methods for Property-Based Metrics
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### Memory Table Enable Methods
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```java { .api }
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public void enableNumImmutableMemTable()
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```
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Enables monitoring of immutable memtable count.
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```java { .api }
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public void enableMemTableFlushPending()
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```
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Enables monitoring of pending memtable flushes.
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```java { .api }
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public RocksDBNativeMetricOptions enableCurSizeActiveMemTable()
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```
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Enables monitoring of active memtable size.
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```java { .api }
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public RocksDBNativeMetricOptions enableCurSizeAllMemTables()
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```
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Enables monitoring of all memtables size.
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```java { .api }
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public RocksDBNativeMetricOptions enableSizeAllMemTables()
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```
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Enables monitoring of total memtables size.
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```java { .api }
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public RocksDBNativeMetricOptions enableNumEntriesActiveMemTable()
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```
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Enables monitoring of active memtable entries.
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```java { .api }
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public RocksDBNativeMetricOptions enableNumEntriesImmMemTables()
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```
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Enables monitoring of immutable memtable entries.
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```java { .api }
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public RocksDBNativeMetricOptions enableNumDeletesActiveMemTable()
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```
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Enables monitoring of delete entries in active memtable.
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```java { .api }
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public RocksDBNativeMetricOptions enableNumDeletesImmMemTables()
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```
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Enables monitoring of delete entries in immutable memtables.
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### Compaction Enable Methods
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```java { .api }
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public RocksDBNativeMetricOptions enableCompactionPending()
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```
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Enables monitoring of pending compactions.
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```java { .api }
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public RocksDBNativeMetricOptions enableBackgroundErrors()
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```
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Enables monitoring of background errors.
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```java { .api }
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public RocksDBNativeMetricOptions enableNumRunningCompactions()
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```
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Enables monitoring of running compactions.
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```java { .api }
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public RocksDBNativeMetricOptions enableNumRunningFlushes()
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```
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Enables monitoring of running flushes.
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```java { .api }
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public RocksDBNativeMetricOptions enableEstimatePendingCompactionBytes()
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```
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Enables estimation of pending compaction bytes.
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### Database Metrics Enable Methods
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```java { .api }
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public RocksDBNativeMetricOptions enableEstimateNumKeys()
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```
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Enables estimation of key count.
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```java { .api }
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public RocksDBNativeMetricOptions enableEstimateTableReadersMem()
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```
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Enables estimation of table readers memory.
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```java { .api }
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public RocksDBNativeMetricOptions enableEstimateLiveDataSize()
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```
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Enables estimation of live data size.
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```java { .api }
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public RocksDBNativeMetricOptions enableTotalSstFilesSize()
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```
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Enables monitoring of total SST files size.
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```java { .api }
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public RocksDBNativeMetricOptions enableLiveSstFilesSize()
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```
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Enables monitoring of live SST files size.
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### Cache Enable Methods
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```java { .api }
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public RocksDBNativeMetricOptions enableBlockCacheCapacity()
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```
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Enables monitoring of block cache capacity.
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```java { .api }
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public RocksDBNativeMetricOptions enableBlockCacheUsage()
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```
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Enables monitoring of block cache usage.
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```java { .api }
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public RocksDBNativeMetricOptions enableBlockCachePinnedUsage()
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```
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Enables monitoring of pinned block cache usage.
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### Snapshot and Version Enable Methods
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```java { .api }
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public RocksDBNativeMetricOptions enableNumSnapshots()
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```
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Enables monitoring of unreleased snapshots.
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```java { .api }
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public RocksDBNativeMetricOptions enableNumLiveVersions()
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```
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Enables monitoring of live versions.
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### Write Performance Enable Methods
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```java { .api }
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public RocksDBNativeMetricOptions enableActualDelayedWriteRate()
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```
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Enables monitoring of delayed write rate.
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```java { .api }
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public RocksDBNativeMetricOptions enableIsWriteStopped()
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```
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Enables monitoring of write stopped status.
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### File Level Enable Methods
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```java { .api }
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public RocksDBNativeMetricOptions enableNumFilesAtLevel()
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```
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Enables monitoring of files per LSM tree level.
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## Configuration Methods
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### Column Family Configuration
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```java { .api }
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public void setColumnFamilyAsVariable(boolean columnFamilyAsVariable)
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```
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Sets whether to expose column family name as a variable in metric names.
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**Parameters:**
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- `columnFamilyAsVariable` - Whether to include column family in metric names
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### Statistics Configuration
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```java { .api }
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public void enableNativeStatistics(ConfigOption<Boolean> nativeStatisticsOption)
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```
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Enables a native statistics metric.
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**Parameters:**
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- `nativeStatisticsOption` - The statistics option to enable
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## Query Methods
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### Status Methods
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```java { .api }
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public boolean isEnabled()
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```
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Checks if any metrics are enabled.
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**Returns:** `true` if any metrics are configured, `false` otherwise
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```java { .api }
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public boolean isStatisticsEnabled()
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```
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Checks if statistics-based metrics are enabled.
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**Returns:** `true` if statistics metrics are enabled, `false` otherwise
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```java { .api }
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public boolean isColumnFamilyAsVariable()
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```
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Checks if column family is exposed as a variable in metric names.
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**Returns:** `true` if column family is used as variable, `false` otherwise
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### Metrics Collection Methods
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```java { .api }
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public Set<RocksDBProperty> getProperties()
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```
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Gets the set of enabled property-based metrics.
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**Returns:** Set of enabled RocksDBProperty instances
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```java { .api }
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public Collection<ConfigOption<Boolean>> getMonitorTickerTypes()
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```
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Gets the collection of enabled statistics-based metrics.
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**Returns:** Collection of enabled statistics metric options
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## RocksDBProperty Enum
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### Property Enum Definition
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```java { .api }
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@Internal  // Referenced in public APIs
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public enum RocksDBProperty {
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    NumImmutableMemTable,
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    MemTableFlushPending,
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    CompactionPending,
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    BackgroundErrors,
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    CurSizeActiveMemTable,
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    CurSizeAllMemTables,
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    SizeAllMemTables,
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    NumEntriesActiveMemTable,
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    NumEntriesImmMemTables,
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    EstimateNumKeys,
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    EstimateTableReadersMem,
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    NumSnapshots,
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    EstimateLiveDataSize,
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    TotalSstFilesSize,
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    LiveSstFilesSize,
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    BlockCacheCapacity,
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    BlockCacheUsage,
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    BlockCachePinnedUsage,
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    NumFilesAtLevel0,
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    NumFilesAtLevel1,
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    NumFilesAtLevel2,
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    NumFilesAtLevel3,
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    NumFilesAtLevel4,
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    NumFilesAtLevel5,
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    NumFilesAtLevel6
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    // ... and more levels
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}
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```
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### Property Methods
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```java { .api }
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public String getRocksDBProperty()
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```
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Gets the RocksDB property string for querying.
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**Returns:** RocksDB property name string
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```java { .api }
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public long getNumericalPropertyValue(RocksDB rocksDB, ColumnFamilyHandle handle)
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```
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Gets the numerical value of this property from RocksDB.
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**Parameters:**
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- `rocksDB` - RocksDB instance to query
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- `handle` - Column family handle
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**Returns:** Numerical property value
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```java { .api }
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public String getConfigKey()
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```
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Gets the configuration key for this property.
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**Returns:** Configuration key string
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## Configuration Examples
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### Basic Metrics Configuration
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```java
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Configuration config = new Configuration();
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// Enable essential performance metrics
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config.set(RocksDBNativeMetricOptions.MONITOR_BLOCK_CACHE_HIT, true);
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config.set(RocksDBNativeMetricOptions.MONITOR_BLOCK_CACHE_MISS, true);
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config.set(RocksDBNativeMetricOptions.ESTIMATE_NUM_KEYS, true);
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config.set(RocksDBNativeMetricOptions.MONITOR_COMPACTION_READ_BYTES, true);
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config.set(RocksDBNativeMetricOptions.MONITOR_COMPACTION_WRITE_BYTES, true);
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// Create options from config
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RocksDBNativeMetricOptions metricOptions = RocksDBNativeMetricOptions.fromConfig(config);
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```
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### Memory Monitoring Configuration
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```java
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Configuration config = new Configuration();
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// Memory-related metrics
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config.set(RocksDBNativeMetricOptions.MONITOR_CUR_SIZE_ACTIVE_MEM_TABLE, true);
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config.set(RocksDBNativeMetricOptions.MONITOR_CUR_SIZE_ALL_MEM_TABLE, true);
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config.set(RocksDBNativeMetricOptions.BLOCK_CACHE_USAGE, true);
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config.set(RocksDBNativeMetricOptions.BLOCK_CACHE_CAPACITY, true);
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config.set(RocksDBNativeMetricOptions.ESTIMATE_TABLE_READERS_MEM, true);
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// Compaction and flush monitoring
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config.set(RocksDBNativeMetricOptions.MONITOR_MEM_TABLE_FLUSH_PENDING, true);
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config.set(RocksDBNativeMetricOptions.TRACK_COMPACTION_PENDING, true);
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config.set(RocksDBNativeMetricOptions.MONITOR_NUM_RUNNING_COMPACTIONS, true);
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RocksDBNativeMetricOptions memoryMetrics = RocksDBNativeMetricOptions.fromConfig(config);
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```
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### Comprehensive Monitoring Configuration
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```java
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public RocksDBNativeMetricOptions createComprehensiveMetrics() {
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    Configuration config = new Configuration();
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    // Performance metrics
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    config.set(RocksDBNativeMetricOptions.MONITOR_BLOCK_CACHE_HIT, true);
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    config.set(RocksDBNativeMetricOptions.MONITOR_BLOCK_CACHE_MISS, true);
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    config.set(RocksDBNativeMetricOptions.MONITOR_BLOOM_FILTER_USEFUL, true);
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    // Memory metrics
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    config.set(RocksDBNativeMetricOptions.BLOCK_CACHE_USAGE, true);
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    config.set(RocksDBNativeMetricOptions.MONITOR_CUR_SIZE_ALL_MEM_TABLE, true);
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    config.set(RocksDBNativeMetricOptions.ESTIMATE_TABLE_READERS_MEM, true);
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    // I/O metrics
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    config.set(RocksDBNativeMetricOptions.MONITOR_BYTES_READ, true);
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    config.set(RocksDBNativeMetricOptions.MONITOR_BYTES_WRITTEN, true);
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    config.set(RocksDBNativeMetricOptions.MONITOR_COMPACTION_READ_BYTES, true);
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    config.set(RocksDBNativeMetricOptions.MONITOR_COMPACTION_WRITE_BYTES, true);
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    // Database health metrics
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    config.set(RocksDBNativeMetricOptions.ESTIMATE_NUM_KEYS, true);
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    config.set(RocksDBNativeMetricOptions.ESTIMATE_LIVE_DATA_SIZE, true);
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    config.set(RocksDBNativeMetricOptions.MONITOR_BACKGROUND_ERRORS, true);
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    config.set(RocksDBNativeMetricOptions.IS_WRITE_STOPPED, true);
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    // Compaction metrics
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    config.set(RocksDBNativeMetricOptions.TRACK_COMPACTION_PENDING, true);
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    config.set(RocksDBNativeMetricOptions.MONITOR_NUM_RUNNING_COMPACTIONS, true);
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    config.set(RocksDBNativeMetricOptions.ESTIMATE_PENDING_COMPACTION_BYTES, true);
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    // Column family as variable for better metric organization
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    config.set(RocksDBNativeMetricOptions.COLUMN_FAMILY_AS_VARIABLE, true);
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622
    return RocksDBNativeMetricOptions.fromConfig(config);
623
}
624
```
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### Programmatic Metrics Configuration
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```java
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public RocksDBNativeMetricOptions createProgrammaticMetrics() {
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    RocksDBNativeMetricOptions metrics = new RocksDBNativeMetricOptions();
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632
    // Enable using method calls
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    metrics.enableBlockCacheUsage();
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    metrics.enableBlockCacheCapacity();
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    metrics.enableEstimateNumKeys();
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    metrics.enableEstimateLiveDataSize();
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    metrics.enableCompactionPending();
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    metrics.enableBackgroundErrors();
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    metrics.setColumnFamilyAsVariable(true);
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641
    return metrics;
642
}
643
```
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## Integration with Options Factory
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```java
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import org.apache.flink.state.rocksdb.RocksDBOptionsFactory;
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public class MetricsEnabledOptionsFactory implements RocksDBOptionsFactory {
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652
    @Override
653
    public RocksDBNativeMetricOptions createNativeMetricsOptions(
654
            RocksDBNativeMetricOptions nativeMetricOptions) {
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656
        // Override default metrics with custom configuration
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        nativeMetricOptions.enableBlockCacheUsage();
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        nativeMetricOptions.enableEstimateNumKeys();
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        nativeMetricOptions.enableCompactionPending();
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        nativeMetricOptions.enableBackgroundErrors();
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        nativeMetricOptions.setColumnFamilyAsVariable(true);
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663
        return nativeMetricOptions;
664
    }
665
    
666
    // ... other factory methods
667
}
668
```
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## Metrics Integration with Flink
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### YAML Configuration
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```yaml
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# flink-conf.yaml
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state.backend.rocksdb.metrics.block-cache-hit: true
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state.backend.rocksdb.metrics.block-cache-miss: true  
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state.backend.rocksdb.metrics.estimate-num-keys: true
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state.backend.rocksdb.metrics.compaction-read-bytes: true
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state.backend.rocksdb.metrics.compaction-write-bytes: true
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state.backend.rocksdb.metrics.column-family-as-variable: true
682
```
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### Runtime Monitoring
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The enabled metrics will be automatically forwarded to Flink's metrics system and can be accessed through:
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- **Flink Web UI**: Metrics section showing RocksDB metrics per operator
689
- **Metrics Reporters**: JMX, Prometheus, InfluxDB, etc.
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- **REST API**: Flink REST API for programmatic access
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- **Logging**: Metrics can be logged periodically
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### Metric Naming Convention
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Metrics follow this naming pattern:
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```
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<job_name>.<operator_name>.rocksdb.[column_family.]<metric_name>
698
```
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Example metric names:
701
- `my_job.my_operator.rocksdb.estimate-num-keys`
702
- `my_job.my_operator.rocksdb.default.block-cache-usage` (with column family)
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- `my_job.my_operator.rocksdb.compaction-read-bytes`
704

705
## Performance Considerations
706

707
### Metrics Overhead
708
- Property-based metrics have minimal overhead (simple property reads)
709
- Statistics-based metrics require RocksDB statistics collection (slight overhead)
710
- Enable only necessary metrics for production to minimize impact
711

712
### Useful Metric Combinations
713

714
**Performance Monitoring:**
715
- Block cache hit/miss ratio
716
- Compaction read/write bytes  
717
- Write stall duration
718

719
**Memory Monitoring:**
720
- Block cache usage vs capacity
721
- Memtable sizes
722
- Table readers memory
723

724
**Health Monitoring:**
725
- Background errors
726
- Write stopped status
727
- Pending compactions
728

729
**Capacity Planning:**
730
- Estimate number of keys
731
- Live data size
732
- Total SST file size