This documentation is for an unreleased version of Apache Paimon. We recommend you use the latest stable version.
Metrics
Paimon Metrics #
Paimon has built a metrics system to measure the behaviours of reading and writing, like how many manifest files it scanned in the last planning, how long it took in the last commit operation, how many files it deleted in the last compact operation.
In Paimon’s metrics system, metrics are updated and reported at table granularity.
There are three types of metrics provided in the Paimon metric system, Gauge, Counter, Histogram.
Gauge: Provides a value of any type at a point in time.Counter: Used to count values by incrementing and decrementing.Histogram: Measure the statistical distribution of a set of values including the min, max, mean, standard deviation and percentile.
Paimon has supported built-in metrics to measure operations of commits, scans, writes and compactions, which can be bridged to any computing engine that supports, like Flink, Spark etc.
Metrics List #
Below is lists of Paimon built-in metrics. They are summarized into types of scan metrics, commit metrics, write metrics, write buffer metrics and compaction metrics.
Scan Metrics #
| Metrics Name | Type | Description |
|---|---|---|
| lastScanDuration | Gauge | The time it took to complete the last scan. |
| scanDuration | Histogram | Distributions of the time taken by the last few scans. |
| lastScannedManifests | Gauge | Number of scanned manifest files in the last scan. |
| lastSkippedByPartitionAndStats | Gauge | Skipped table files by partition filter and value / key stats information in the last scan. |
| lastSkippedByWholeBucketFilesFilter | Gauge | Skipped table files by bucket level value filter (only primary key table) in the last scan. |
| lastScanSkippedTableFiles | Gauge | Total skipped table files in the last scan. |
| lastScanResultedTableFiles | Gauge | Resulted table files in the last scan. |
Commit Metrics #
| Metrics Name | Type | Description |
|---|---|---|
| lastCommitDuration | Gauge | The time it took to complete the last commit. |
| commitDuration | Histogram | Distributions of the time taken by the last few commits. |
| lastCommitAttempts | Gauge | The number of attempts the last commit made. |
| lastTableFilesAdded | Gauge | Number of added table files in the last commit, including newly created data files and compacted after. |
| lastTableFilesDeleted | Gauge | Number of deleted table files in the last commit, which comes from compacted before. |
| lastTableFilesAppended | Gauge | Number of appended table files in the last commit, which means the newly created data files. |
| lastTableFilesCommitCompacted | Gauge | Number of compacted table files in the last commit, including compacted before and after. |
| lastChangelogFilesAppended | Gauge | Number of appended changelog files in last commit. |
| lastChangelogFileCommitCompacted | Gauge | Number of compacted changelog files in last commit. |
| lastGeneratedSnapshots | Gauge | Number of snapshot files generated in the last commit, maybe 1 snapshot or 2 snapshots. |
| lastDeltaRecordsAppended | Gauge | Delta records count in last commit with APPEND commit kind. |
| lastChangelogRecordsAppended | Gauge | Changelog records count in last commit with APPEND commit kind. |
| lastDeltaRecordsCommitCompacted | Gauge | Delta records count in last commit with COMPACT commit kind. |
| lastChangelogRecordsCommitCompacted | Gauge | Changelog records count in last commit with COMPACT commit kind. |
| lastPartitionsWritten | Gauge | Number of partitions written in the last commit. |
| lastBucketsWritten | Gauge | Number of buckets written in the last commit. |
| lastCompactionInputFileSize | Gauge | Total size of the input files for the last compaction. |
| lastCompactionOutputFileSize | Gauge | Total size of the output files for the last compaction. |
Write Buffer Metrics #
| Metrics Name | Type | Description |
|---|---|---|
| numWriters | Gauge | Number of writers in this parallelism. |
| bufferPreemptCount | Gauge | The total number of memory preempted. |
| usedWriteBufferSizeByte | Gauge | Current used write buffer size in byte. |
| totalWriteBufferSizeByte | Gauge | The total write buffer size configured in byte. |
Compaction Metrics #
| Metrics Name | Type | Description |
|---|---|---|
| maxLevel0FileCount | Gauge | The maximum number of level 0 files currently handled by this task. This value will become larger if asynchronous compaction cannot be done in time. |
| avgLevel0FileCount | Gauge | The average number of level 0 files currently handled by this task. This value will become larger if asynchronous compaction cannot be done in time. |
| compactionThreadBusy | Gauge | The maximum business of compaction threads in this task. Currently, there is only one compaction thread in each parallelism, so value of business ranges from 0 (idle) to 100 (compaction running all the time). |
| avgCompactionTime | Gauge | The average runtime of compaction threads, calculated based on recorded compaction time data in milliseconds. The value represents the average duration of compaction operations. Higher values indicate longer average compaction times, which may suggest the need for performance optimization. |
| compactionCompletedCount | Counter | The total number of compactions that have completed. |
| compactionQueuedCount | Counter | The total number of compactions that are queued/running. |
| maxCompactionInputSize | Gauge | The maximum input file size for this task's compaction. |
| avgCompactionInputSize/td> | Gauge | The average input file size for this task's compaction. |
| maxCompactionOutputSize | Gauge | The maximum output file size for this task's compaction. |
| avgCompactionOutputSize | Gauge | The average output file size for this task's compaction. |
Bridging To Flink #
Paimon has implemented bridging metrics to Flink’s metrics system, which can be reported by Flink, and the lifecycle of metric groups are managed by Flink.
Please join the <scope>.<infix>.<metric_name> to get the complete metric identifier when using Flink to access Paimon, metric_name can be got from Metric List.
For example, the identifier of metric lastPartitionsWritten for table word_count in Flink job named insert_word_count is:
localhost.taskmanager.localhost:60340-775a20.insert_word_count.Global Committer : word_count.0.paimon.table.word_count.commit.lastPartitionsWritten.
From Flink Web-UI, go to the committer operator’s metrics, it’s shown as:
0.Global_Committer___word_count.paimon.table.word_count.commit.lastPartitionsWritten.
- Please refer to System Scope to understand Flink
scope- Scan metrics are only supported by Flink versions >= 1.18
| Scope | Infix | |
|---|---|---|
| Scan Metrics | <host>.jobmanager.<job_name> | <source_operator_name>.coordinator. enumerator.paimon.table.<table_name>.scan |
| Commit Metrics | <host>.taskmanager.<tm_id>.<job_name>.<committer_operator_name>.<subtask_index> | paimon.table.<table_name>.commit |
| Write Metrics | <host>.taskmanager.<tm_id>.<job_name>.<writer_operator_name>.<subtask_index> | paimon.table.<table_name>.partition.<partition_string>.bucket.<bucket_index>.writer |
| Write Buffer Metrics | <host>.taskmanager.<tm_id>.<job_name>.<writer_operator_name>.<subtask_index> | paimon.table.<table_name>.writeBuffer |
| Compaction Metrics | <host>.taskmanager.<tm_id>.<job_name>.<writer_operator_name>.<subtask_index> | paimon.table.<table_name>.partition.<partition_string>.bucket.<bucket_index>.compaction |
| Flink Source Metrics | <host>.taskmanager.<tm_id>.<job_name>.<source_operator_name>.<subtask_index> | - |
| Flink Sink Metrics | <host>.taskmanager.<tm_id>.<job_name>.<committer_operator_name>.<subtask_index> | - |
Flink Connector Standard Metrics #
When using Flink to read and write, Paimon has implemented some key standard Flink connector metrics to measure the source latency and output of sink, see FLIP-33: Standardize Connector Metrics. Flink source / sink metrics implemented are listed here.
Source Metrics (Flink) #
| Metrics Name | Level | Type | Description |
|---|---|---|---|
| currentEmitEventTimeLag | Flink Source Operator | Gauge | Time difference between sending the record out of source and file creation. |
| currentFetchEventTimeLag | Flink Source Operator | Gauge | Time difference between reading the data file and file creation. |
Please note that if you specifiedconsumer-idin your streaming query, the level of source metrics should turn into the reader operator, which is behind theMonitoroperator.
Sink Metrics (Flink) #
| Metrics Name | Level | Type | Description |
|---|---|---|---|
| numBytesOut | Table | Counter | The total number of output bytes. |
| numBytesOutPerSecond | Table | Meter | The output bytes per second. |
| numRecordsOut | Table | Counter | The total number of output records. |
| numRecordsOutPerSecond | Table | Meter | The output records per second. |