druid/native-batch.md at 3e92cdf1cfcde8447e3a61dfe36eb813716ad202

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id	title	sidebar_label
native-batch	Native batch ingestion	Native batch

Apache Druid currently has two types of native batch indexing tasks, index_parallel which can run multiple tasks in parallel, and index which will run a single indexing task. Please refer to our Hadoop-based vs. native batch comparison table for comparisons between Hadoop-based, native batch (simple), and native batch (parallel) ingestion.

To run either kind of native batch indexing task, write an ingestion spec as specified below. Then POST it to the /druid/indexer/v1/task endpoint on the Overlord, or use the bin/post-index-task script included with Druid.

Tutorial

This page contains reference documentation for native batch ingestion. For a walk-through instead, check out the Loading a file tutorial, which demonstrates the "simple" (single-task) mode.

Parallel task

The Parallel task (type index_parallel) is a task for parallel batch indexing. This task only uses Druid's resource and doesn't depend on other external systems like Hadoop. The index_parallel task is a supervisor task that orchestrates the whole indexing process. The supervisor task splits the input data and creates worker tasks to process those splits. The created worker tasks are issued to the Overlord so that they can be scheduled and run on MiddleManagers or Indexers. Once a worker task successfully processes the assigned input split, it reports the generated segment list to the supervisor task. The supervisor task periodically checks the status of worker tasks. If one of them fails, it retries the failed task until the number of retries reaches the configured limit. If all worker tasks succeed, it publishes the reported segments at once and finalizes ingestion.

The detailed behavior of the Parallel task is different depending on the partitionsSpec. See each partitionsSpec for more details.

To use this task, the inputSource in the ioConfig should be splittable and maxNumConcurrentSubTasks should be set to larger than 1 in the tuningConfig. Otherwise, this task runs sequentially; the index_parallel task reads each input file one by one and creates segments by itself. The supported splittable input formats for now are:

s3 reads data from AWS S3 storage.
gs reads data from Google Cloud Storage.
azure reads data from Azure Blob Storage.
hdfs reads data from HDFS storage.
http reads data from HTTP servers.
local reads data from local storage.
druid reads data from a Druid datasource.
sql reads data from a RDBMS source.

Some other cloud storage types are supported with the legacy firehose. The below firehose types are also splittable. Note that only text formats are supported with the firehose.

static-cloudfiles

You may want to consider the below things:

You may want to control the amount of input data each worker task processes. This can be controlled using different configurations depending on the phase in parallel ingestion (see partitionsSpec for more details). For the tasks that read data from the inputSource, you can set the Split hint spec in the tuningConfig. For the tasks that merge shuffled segments, you can set the totalNumMergeTasks in the tuningConfig.
The number of concurrent worker tasks in parallel ingestion is determined by maxNumConcurrentSubTasks in the tuningConfig. The supervisor task checks the number of current running worker tasks and creates more if it's smaller than maxNumConcurrentSubTasks no matter how many task slots are currently available. This may affect to other ingestion performance. See the below Capacity Planning section for more details.
By default, batch ingestion replaces all data (in your granularitySpec's intervals) in any segment that it writes to. If you'd like to add to the segment instead, set the appendToExisting flag in the ioConfig. Note that it only replaces data in segments where it actively adds data: if there are segments in your granularitySpec's intervals that have no data written by this task, they will be left alone. If any existing segments partially overlap with the granularitySpec's intervals, the portion of those segments outside the new segments' intervals will still be visible.

Task syntax

A sample task is shown below:

{
  "type": "index_parallel",
  "spec": {
    "dataSchema": {
      "dataSource": "wikipedia_parallel_index_test",
      "timestampSpec": {
        "column": "timestamp"
      },
      "dimensionsSpec": {
        "dimensions": [
          "page",
          "language",
          "user",
          "unpatrolled",
          "newPage",
          "robot",
          "anonymous",
          "namespace",
          "continent",
          "country",
          "region",
          "city"
        ]
      },
      "metricsSpec": [
        {
          "type": "count",
              "name": "count"
            },
            {
              "type": "doubleSum",
              "name": "added",
              "fieldName": "added"
            },
            {
              "type": "doubleSum",
              "name": "deleted",
              "fieldName": "deleted"
            },
            {
              "type": "doubleSum",
              "name": "delta",
              "fieldName": "delta"
            }
        ],
        "granularitySpec": {
          "segmentGranularity": "DAY",
          "queryGranularity": "second",
          "intervals" : [ "2013-08-31/2013-09-02" ]
        }
    },
    "ioConfig": {
        "type": "index_parallel",
        "inputSource": {
          "type": "local",
          "baseDir": "examples/indexing/",
          "filter": "wikipedia_index_data*"
        },
        "inputFormat": {
          "type": "json"
        }
    },
    "tuningconfig": {
        "type": "index_parallel",
        "maxNumConcurrentSubTasks": 2
    }
  }
}

property	description	required?
type	The task type, this should always be `index_parallel`.	yes
id	The task ID. If this is not explicitly specified, Druid generates the task ID using task type, data source name, interval, and date-time stamp.	no
spec	The ingestion spec including the data schema, IOConfig, and TuningConfig. See below for more details.	yes
context	Context containing various task configuration parameters. See below for more details.	no

`dataSchema`

This field is required.

See Ingestion Spec DataSchema

If you specify intervals explicitly in your dataSchema's granularitySpec, batch ingestion will lock the full intervals specified when it starts up, and you will learn quickly if the specified interval overlaps with locks held by other tasks (e.g., Kafka ingestion). Otherwise, batch ingestion will lock each interval as it is discovered, so you may only learn that the task overlaps with a higher-priority task later in ingestion. If you specify intervals explicitly, any rows outside the specified intervals will be thrown away. We recommend setting intervals explicitly if you know the time range of the data so that locking failure happens faster, and so that you don't accidentally replace data outside that range if there's some stray data with unexpected timestamps.

`ioConfig`

property	description	default	required?
type	The task type, this should always be `index_parallel`.	none	yes
inputFormat	`inputFormat` to specify how to parse input data.	none	yes
appendToExisting	Creates segments as additional shards of the latest version, effectively appending to the segment set instead of replacing it. The current limitation is that you can append to any datasources regardless of their original partitioning scheme, but the appended segments should be partitioned using the `dynamic` partitionsSpec.	false	no

`tuningConfig`

The tuningConfig is optional and default parameters will be used if no tuningConfig is specified. See below for more details.

property	description	default	required?
type	The task type, this should always be `index_parallel`.	none	yes
maxRowsPerSegment	Deprecated. Use `partitionsSpec` instead. Used in sharding. Determines how many rows are in each segment.	5000000	no
maxRowsInMemory	Used in determining when intermediate persists to disk should occur. Normally user does not need to set this, but depending on the nature of data, if rows are short in terms of bytes, user may not want to store a million rows in memory and this value should be set.	1000000	no
maxBytesInMemory	Used in determining when intermediate persists to disk should occur. Normally this is computed internally and user does not need to set it. This value represents number of bytes to aggregate in heap memory before persisting. This is based on a rough estimate of memory usage and not actual usage. The maximum heap memory usage for indexing is maxBytesInMemory * (2 + maxPendingPersists)	1/6 of max JVM memory	no
maxTotalRows	Deprecated. Use `partitionsSpec` instead. Total number of rows in segments waiting for being pushed. Used in determining when intermediate pushing should occur.	20000000	no
numShards	Deprecated. Use `partitionsSpec` instead. Directly specify the number of shards to create when using a `hashed` `partitionsSpec`. If this is specified and `intervals` is specified in the `granularitySpec`, the index task can skip the determine intervals/partitions pass through the data. `numShards` cannot be specified if `maxRowsPerSegment` is set.	null	no
splitHintSpec	Used to give a hint to control the amount of data that each first phase task reads. This hint could be ignored depending on the implementation of the input source. See Split hint spec for more details.	size-based split hint spec	no
partitionsSpec	Defines how to partition data in each timeChunk, see PartitionsSpec	`dynamic` if `forceGuaranteedRollup` = false, `hashed` or `single_dim` if `forceGuaranteedRollup` = true	no
indexSpec	Defines segment storage format options to be used at indexing time, see IndexSpec	null	no
indexSpecForIntermediatePersists	Defines segment storage format options to be used at indexing time for intermediate persisted temporary segments. this can be used to disable dimension/metric compression on intermediate segments to reduce memory required for final merging. however, disabling compression on intermediate segments might increase page cache use while they are used before getting merged into final segment published, see IndexSpec for possible values.	same as indexSpec	no
maxPendingPersists	Maximum number of persists that can be pending but not started. If this limit would be exceeded by a new intermediate persist, ingestion will block until the currently-running persist finishes. Maximum heap memory usage for indexing scales with maxRowsInMemory * (2 + maxPendingPersists).	0 (meaning one persist can be running concurrently with ingestion, and none can be queued up)	no
forceGuaranteedRollup	Forces guaranteeing the perfect rollup. The perfect rollup optimizes the total size of generated segments and querying time while indexing time will be increased. If this is set to true, `intervals` in `granularitySpec` must be set and `hashed` or `single_dim` must be used for `partitionsSpec`. This flag cannot be used with `appendToExisting` of IOConfig. For more details, see the below Segment pushing modes section.	false	no
reportParseExceptions	If true, exceptions encountered during parsing will be thrown and will halt ingestion; if false, unparseable rows and fields will be skipped.	false	no
pushTimeout	Milliseconds to wait for pushing segments. It must be >= 0, where 0 means to wait forever.	0	no
segmentWriteOutMediumFactory	Segment write-out medium to use when creating segments. See SegmentWriteOutMediumFactory.	Not specified, the value from `druid.peon.defaultSegmentWriteOutMediumFactory.type` is used	no
maxNumConcurrentSubTasks	Maximum number of worker tasks which can be run in parallel at the same time. The supervisor task would spawn worker tasks up to `maxNumConcurrentSubTasks` regardless of the current available task slots. If this value is set to 1, the supervisor task processes data ingestion on its own instead of spawning worker tasks. If this value is set to too large, too many worker tasks can be created which might block other ingestion. Check Capacity Planning for more details.	1	no
maxRetry	Maximum number of retries on task failures.	3	no
maxNumSegmentsToMerge	Max limit for the number of segments that a single task can merge at the same time in the second phase. Used only `forceGuaranteedRollup` is set.	100	no
totalNumMergeTasks	Total number of tasks to merge segments in the merge phase when `partitionsSpec` is set to `hashed` or `single_dim`.	10	no
taskStatusCheckPeriodMs	Polling period in milliseconds to check running task statuses.	1000	no
chatHandlerTimeout	Timeout for reporting the pushed segments in worker tasks.	PT10S	no
chatHandlerNumRetries	Retries for reporting the pushed segments in worker tasks.	5	no

Split Hint Spec

The split hint spec is used to give a hint when the supervisor task creates input splits. Note that each worker task processes a single input split. You can control the amount of data each worker task will read during the first phase.

Size-based Split Hint Spec

The size-based split hint spec is respected by all splittable input sources except for the HTTP input source.

property	description	default	required?
type	This should always be `maxSize`.	none	yes
maxSplitSize	Maximum number of bytes of input files to process in a single task. If a single file is larger than this number, it will be processed by itself in a single task (Files are never split across tasks yet).	500MB	no

Segments Split Hint Spec

The segments split hint spec is used only for DruidInputSource (and legacy IngestSegmentFirehose).

property	description	default	required?
type	This should always be `segments`.	none	yes
maxInputSegmentBytesPerTask	Maximum number of bytes of input segments to process in a single task. If a single segment is larger than this number, it will be processed by itself in a single task (input segments are never split across tasks).	500MB	no

`partitionsSpec`

PartitionsSpec is used to describe the secondary partitioning method. You should use different partitionsSpec depending on the rollup mode you want. For perfect rollup, you should use either hashed (partitioning based on the hash of dimensions in each row) or single_dim (based on ranges of a single dimension). For best-effort rollup, you should use dynamic.

The three partitionsSpec types have different characteristics.

PartitionsSpec	Ingestion speed	Partitioning method	Supported rollup mode	Segment pruning at query time
`dynamic`	Fastest	Partitioning based on number of rows in segment.	Best-effort rollup	N/A
`hashed`	Moderate	Partitioning based on the hash value of partition dimensions. This partitioning may reduce your datasource size and query latency by improving data locality. See Partitioning for more details.	Perfect rollup	N/A
`single_dim`	Slowest	Range partitioning based on the value of the partition dimension. Segment sizes may be skewed depending on the partition key distribution. This may reduce your datasource size and query latency by improving data locality. See Partitioning for more details.	Perfect rollup	The broker can use the partition information to prune segments early to speed up queries. Since the broker knows the range of `partitionDimension` values in each segment, given a query including a filter on the `partitionDimension`, the broker can pick up only the segments holding the rows satisfying the filter on `partitionDimension` for query processing.

The recommended use case for each partitionsSpec is:

If your data has a uniformly distributed column which is frequently used in your queries, consider using single_dim partitionsSpec to maximize the performance of most of your queries.
If your data doesn't a uniformly distributed column, but is expected to have a high rollup ratio when you roll up with some dimensions, consider using hashed partitionsSpec. It could reduce the size of datasource and query latency by improving data locality.
If the above two scenarios are not the case or you don't need to roll up your datasource, consider using dynamic partitionsSpec.

Dynamic partitioning

property	description	default	required?
type	This should always be `dynamic`	none	yes
maxRowsPerSegment	Used in sharding. Determines how many rows are in each segment.	5000000	no
maxTotalRows	Total number of rows across all segments waiting for being pushed. Used in determining when intermediate segment push should occur.	20000000	no

With the Dynamic partitioning, the parallel index task runs in a single phase: it will spawn multiple worker tasks (type single_phase_sub_task), each of which creates segments. How the worker task creates segments is:

The task creates a new segment whenever the number of rows in the current segment exceeds maxRowsPerSegment.
Once the total number of rows in all segments across all time chunks reaches to maxTotalRows, the task pushes all segments created so far to the deep storage and creates new ones.

Hash-based partitioning

property	description	default	required?
type	This should always be `hashed`	none	yes
numShards	Directly specify the number of shards to create. If this is specified and `intervals` is specified in the `granularitySpec`, the index task can skip the determine intervals/partitions pass through the data.	null	yes
partitionDimensions	The dimensions to partition on. Leave blank to select all dimensions.	null	no

The Parallel task with hash-based partitioning is similar to MapReduce. The task runs in 2 phases, i.e., partial segment generation and partial segment merge.

In the partial segment generation phase, just like the Map phase in MapReduce, the Parallel task splits the input data based on the split hint spec and assigns each split to a worker task. Each worker task (type partial_index_generate) reads the assigned split, and partitions rows by the time chunk from segmentGranularity (primary partition key) in the granularitySpec and then by the hash value of partitionDimensions (secondary partition key) in the partitionsSpec. The partitioned data is stored in local storage of the middleManager or the indexer.
The partial segment merge phase is similar to the Reduce phase in MapReduce. The Parallel task spawns a new set of worker tasks (type partial_index_generic_merge) to merge the partitioned data created in the previous phase. Here, the partitioned data is shuffled based on the time chunk and the hash value of partitionDimensions to be merged; each worker task reads the data falling in the same time chunk and the same hash value from multiple MiddleManager/Indexer processes and merges them to create the final segments. Finally, they push the final segments to the deep storage at once.

Single-dimension range partitioning

Single dimension range partitioning is currently not supported in the sequential mode of the Parallel task. Try set maxNumConcurrentSubTasks to larger than 1 to use this partitioning.

property	description	default	required?
type	This should always be `single_dim`	none	yes
partitionDimension	The dimension to partition on. Only rows with a single dimension value are allowed.	none	yes
targetRowsPerSegment	Target number of rows to include in a partition, should be a number that targets segments of 500MB~1GB.	none	either this or `maxRowsPerSegment`
maxRowsPerSegment	Soft max for the number of rows to include in a partition.	none	either this or `targetRowsPerSegment`
assumeGrouped	Assume that input data has already been grouped on time and dimensions. Ingestion will run faster, but may choose sub-optimal partitions if this assumption is violated.	false	no

With single-dim partitioning, the Parallel task runs in 3 phases, i.e., partial dimension distribution, partial segment generation, and partial segment merge. The first phase is to collect some statistics to find the best partitioning and the other 2 phases are to create partial segments and to merge them, respectively, as in hash-based partitioning.

In the partial dimension distribution phase, the Parallel task splits the input data and assigns them to worker tasks based on the split hint spec. Each worker task (type partial_dimension_distribution) reads the assigned split and builds a histogram for partitionDimension. The Parallel task collects those histograms from worker tasks and finds the best range partitioning based on partitionDimension to evenly distribute rows across partitions. Note that either targetRowsPerSegment or maxRowsPerSegment will be used to find the best partitioning.
In the partial segment generation phase, the Parallel task spawns new worker tasks (type partial_range_index_generate) to create partitioned data. Each worker task reads a split created as in the previous phase, partitions rows by the time chunk from the segmentGranularity (primary partition key) in the granularitySpec and then by the range partitioning found in the previous phase. The partitioned data is stored in local storage of the middleManager or the indexer.
In the partial segment merge phase, the parallel index task spawns a new set of worker tasks (type partial_index_generic_merge) to merge the partitioned data created in the previous phase. Here, the partitioned data is shuffled based on the time chunk and the value of partitionDimension; each worker task reads the segments falling in the same partition of the same range from multiple MiddleManager/Indexer processes and merges them to create the final segments. Finally, they push the final segments to the deep storage.

Because the task with single-dimension range partitioning makes two passes over the input in partial dimension distribution and partial segment generation phases, the task may fail if the input changes in between the two passes.

HTTP status endpoints

The supervisor task provides some HTTP endpoints to get running status.

http://{PEON_IP}:{PEON_PORT}/druid/worker/v1/chat/{SUPERVISOR_TASK_ID}/mode

Returns 'parallel' if the indexing task is running in parallel. Otherwise, it returns 'sequential'.

http://{PEON_IP}:{PEON_PORT}/druid/worker/v1/chat/{SUPERVISOR_TASK_ID}/phase

Returns the name of the current phase if the task running in the parallel mode.

http://{PEON_IP}:{PEON_PORT}/druid/worker/v1/chat/{SUPERVISOR_TASK_ID}/progress

Returns the estimated progress of the current phase if the supervisor task is running in the parallel mode.

An example of the result is

{
  "running":10,
  "succeeded":0,
  "failed":0,
  "complete":0,
  "total":10,
  "estimatedExpectedSucceeded":10
}

http://{PEON_IP}:{PEON_PORT}/druid/worker/v1/chat/{SUPERVISOR_TASK_ID}/subtasks/running

Returns the task IDs of running worker tasks, or an empty list if the supervisor task is running in the sequential mode.

http://{PEON_IP}:{PEON_PORT}/druid/worker/v1/chat/{SUPERVISOR_TASK_ID}/subtaskspecs

Returns all worker task specs, or an empty list if the supervisor task is running in the sequential mode.

http://{PEON_IP}:{PEON_PORT}/druid/worker/v1/chat/{SUPERVISOR_TASK_ID}/subtaskspecs/running

Returns running worker task specs, or an empty list if the supervisor task is running in the sequential mode.

http://{PEON_IP}:{PEON_PORT}/druid/worker/v1/chat/{SUPERVISOR_TASK_ID}/subtaskspecs/complete

Returns complete worker task specs, or an empty list if the supervisor task is running in the sequential mode.

http://{PEON_IP}:{PEON_PORT}/druid/worker/v1/chat/{SUPERVISOR_TASK_ID}/subtaskspec/{SUB_TASK_SPEC_ID}

Returns the worker task spec of the given id, or HTTP 404 Not Found error if the supervisor task is running in the sequential mode.

http://{PEON_IP}:{PEON_PORT}/druid/worker/v1/chat/{SUPERVISOR_TASK_ID}/subtaskspec/{SUB_TASK_SPEC_ID}/state

Returns the state of the worker task spec of the given id, or HTTP 404 Not Found error if the supervisor task is running in the sequential mode. The returned result contains the worker task spec, a current task status if exists, and task attempt history.

An example of the result is

{
  "spec": {
    "id": "index_parallel_lineitem_2018-04-20T22:12:43.610Z_2",
    "groupId": "index_parallel_lineitem_2018-04-20T22:12:43.610Z",
    "supervisorTaskId": "index_parallel_lineitem_2018-04-20T22:12:43.610Z",
    "context": null,
    "inputSplit": {
      "split": "/path/to/data/lineitem.tbl.5"
    },
    "ingestionSpec": {
      "dataSchema": {
        "dataSource": "lineitem",
        "timestampSpec": {
          "column": "l_shipdate",
          "format": "yyyy-MM-dd"
        },
        "dimensionsSpec": {
          "dimensions": [
            "l_orderkey",
            "l_partkey",
            "l_suppkey",
            "l_linenumber",
            "l_returnflag",
            "l_linestatus",
            "l_shipdate",
            "l_commitdate",
            "l_receiptdate",
            "l_shipinstruct",
            "l_shipmode",
            "l_comment"
          ]
        },
        "metricsSpec": [
          {
            "type": "count",
            "name": "count"
          },
          {
            "type": "longSum",
            "name": "l_quantity",
            "fieldName": "l_quantity",
            "expression": null
          },
          {
            "type": "doubleSum",
            "name": "l_extendedprice",
            "fieldName": "l_extendedprice",
            "expression": null
          },
          {
            "type": "doubleSum",
            "name": "l_discount",
            "fieldName": "l_discount",
            "expression": null
          },
          {
            "type": "doubleSum",
            "name": "l_tax",
            "fieldName": "l_tax",
            "expression": null
          }
        ],
        "granularitySpec": {
          "type": "uniform",
          "segmentGranularity": "YEAR",
          "queryGranularity": {
            "type": "none"
          },
          "rollup": true,
          "intervals": [
            "1980-01-01T00:00:00.000Z/2020-01-01T00:00:00.000Z"
          ]
        },
        "transformSpec": {
          "filter": null,
          "transforms": []
        }
      },
      "ioConfig": {
        "type": "index_parallel",
        "inputSource": {
          "type": "local",
          "baseDir": "/path/to/data/",
          "filter": "lineitem.tbl.5"
        },
        "inputFormat": {
          "format": "tsv",
          "delimiter": "|",
          "columns": [
            "l_orderkey",
            "l_partkey",
            "l_suppkey",
            "l_linenumber",
            "l_quantity",
            "l_extendedprice",
            "l_discount",
            "l_tax",
            "l_returnflag",
            "l_linestatus",
            "l_shipdate",
            "l_commitdate",
            "l_receiptdate",
            "l_shipinstruct",
            "l_shipmode",
            "l_comment"
          ]
        },
        "appendToExisting": false
      },
      "tuningConfig": {
        "type": "index_parallel",
        "maxRowsPerSegment": 5000000,
        "maxRowsInMemory": 1000000,
        "maxTotalRows": 20000000,
        "numShards": null,
        "indexSpec": {
          "bitmap": {
            "type": "roaring"
          },
          "dimensionCompression": "lz4",
          "metricCompression": "lz4",
          "longEncoding": "longs"
        },
        "indexSpecForIntermediatePersists": {
          "bitmap": {
            "type": "roaring"
          },
          "dimensionCompression": "lz4",
          "metricCompression": "lz4",
          "longEncoding": "longs"
        },
        "maxPendingPersists": 0,
        "reportParseExceptions": false,
        "pushTimeout": 0,
        "segmentWriteOutMediumFactory": null,
        "maxNumConcurrentSubTasks": 4,
        "maxRetry": 3,
        "taskStatusCheckPeriodMs": 1000,
        "chatHandlerTimeout": "PT10S",
        "chatHandlerNumRetries": 5,
        "logParseExceptions": false,
        "maxParseExceptions": 2147483647,
        "maxSavedParseExceptions": 0,
        "forceGuaranteedRollup": false,
        "buildV9Directly": true
      }
    }
  },
  "currentStatus": {
    "id": "index_sub_lineitem_2018-04-20T22:16:29.922Z",
    "type": "index_sub",
    "createdTime": "2018-04-20T22:16:29.925Z",
    "queueInsertionTime": "2018-04-20T22:16:29.929Z",
    "statusCode": "RUNNING",
    "duration": -1,
    "location": {
      "host": null,
      "port": -1,
      "tlsPort": -1
    },
    "dataSource": "lineitem",
    "errorMsg": null
  },
  "taskHistory": []
}

http://{PEON_IP}:{PEON_PORT}/druid/worker/v1/chat/{SUPERVISOR_TASK_ID}/subtaskspec/{SUB_TASK_SPEC_ID}/history

Returns the task attempt history of the worker task spec of the given id, or HTTP 404 Not Found error if the supervisor task is running in the sequential mode.

Capacity planning

The supervisor task can create up to maxNumConcurrentSubTasks worker tasks no matter how many task slots are currently available. As a result, total number of tasks which can be run at the same time is (maxNumConcurrentSubTasks + 1) (including the supervisor task). Please note that this can be even larger than total number of task slots (sum of the capacity of all workers). If maxNumConcurrentSubTasks is larger than n (available task slots), then maxNumConcurrentSubTasks tasks are created by the supervisor task, but only n tasks would be started. Others will wait in the pending state until any running task is finished.

If you are using the Parallel Index Task with stream ingestion together, we would recommend to limit the max capacity for batch ingestion to prevent stream ingestion from being blocked by batch ingestion. Suppose you have t Parallel Index Tasks to run at the same time, but want to limit the max number of tasks for batch ingestion to b. Then, (sum of maxNumConcurrentSubTasks of all Parallel Index Tasks + t (for supervisor tasks)) must be smaller than b.

If you have some tasks of a higher priority than others, you may set their maxNumConcurrentSubTasks to a higher value than lower priority tasks. This may help the higher priority tasks to finish earlier than lower priority tasks by assigning more task slots to them.

Simple task

The simple task (type index) is designed to be used for smaller data sets. The task executes within the indexing service.

Task syntax

A sample task is shown below:

{
  "type" : "index",
  "spec" : {
    "dataSchema" : {
      "dataSource" : "wikipedia",
      "timestampSpec" : {
        "column" : "timestamp",
        "format" : "auto"
      },
      "dimensionsSpec" : {
        "dimensions": ["page","language","user","unpatrolled","newPage","robot","anonymous","namespace","continent","country","region","city"],
        "dimensionExclusions" : []
      },
      "metricsSpec" : [
        {
          "type" : "count",
          "name" : "count"
        },
        {
          "type" : "doubleSum",
          "name" : "added",
          "fieldName" : "added"
        },
        {
          "type" : "doubleSum",
          "name" : "deleted",
          "fieldName" : "deleted"
        },
        {
          "type" : "doubleSum",
          "name" : "delta",
          "fieldName" : "delta"
        }
      ],
      "granularitySpec" : {
        "type" : "uniform",
        "segmentGranularity" : "DAY",
        "queryGranularity" : "NONE",
        "intervals" : [ "2013-08-31/2013-09-01" ]
      }
    },
    "ioConfig" : {
      "type" : "index",
      "inputSource" : {
        "type" : "local",
        "baseDir" : "examples/indexing/",
        "filter" : "wikipedia_data.json"
       },
       "inputFormat": {
         "type": "json"
       }
    },
    "tuningConfig" : {
      "type" : "index",
      "maxRowsPerSegment" : 5000000,
      "maxRowsInMemory" : 1000000
    }
  }
}

property	description	required?
type	The task type, this should always be `index`.	yes
id	The task ID. If this is not explicitly specified, Druid generates the task ID using task type, data source name, interval, and date-time stamp.	no
spec	The ingestion spec including the data schema, IOConfig, and TuningConfig. See below for more details.	yes
context	Context containing various task configuration parameters. See below for more details.	no

`dataSchema`

This field is required.

See the dataSchema section of the ingestion docs for details.

If you do not specify intervals explicitly in your dataSchema's granularitySpec, the Local Index Task will do an extra pass over the data to determine the range to lock when it starts up. If you specify intervals explicitly, any rows outside the specified intervals will be thrown away. We recommend setting intervals explicitly if you know the time range of the data because it allows the task to skip the extra pass, and so that you don't accidentally replace data outside that range if there's some stray data with unexpected timestamps.

`ioConfig`

property	description	default	required?
type	The task type, this should always be "index".	none	yes
inputFormat	`inputFormat` to specify how to parse input data.	none	yes
appendToExisting	Creates segments as additional shards of the latest version, effectively appending to the segment set instead of replacing it. The current limitation is that you can append to any datasources regardless of their original partitioning scheme, but the appended segments should be partitioned using the `dynamic` partitionsSpec.	false	no

`tuningConfig`

The tuningConfig is optional and default parameters will be used if no tuningConfig is specified. See below for more details.

property	description	default	required?
type	The task type, this should always be "index".	none	yes
maxRowsPerSegment	Deprecated. Use `partitionsSpec` instead. Used in sharding. Determines how many rows are in each segment.	5000000	no
maxRowsInMemory	Used in determining when intermediate persists to disk should occur. Normally user does not need to set this, but depending on the nature of data, if rows are short in terms of bytes, user may not want to store a million rows in memory and this value should be set.	1000000	no
maxBytesInMemory	Used in determining when intermediate persists to disk should occur. Normally this is computed internally and user does not need to set it. This value represents number of bytes to aggregate in heap memory before persisting. This is based on a rough estimate of memory usage and not actual usage. The maximum heap memory usage for indexing is maxBytesInMemory * (2 + maxPendingPersists)	1/6 of max JVM memory	no
maxTotalRows	Deprecated. Use `partitionsSpec` instead. Total number of rows in segments waiting for being pushed. Used in determining when intermediate pushing should occur.	20000000	no
numShards	Deprecated. Use `partitionsSpec` instead. Directly specify the number of shards to create. If this is specified and `intervals` is specified in the `granularitySpec`, the index task can skip the determine intervals/partitions pass through the data. `numShards` cannot be specified if `maxRowsPerSegment` is set.	null	no
partitionDimensions	Deprecated. Use `partitionsSpec` instead. The dimensions to partition on. Leave blank to select all dimensions. Only used with `forceGuaranteedRollup` = true, will be ignored otherwise.	null	no
partitionsSpec	Defines how to partition data in each timeChunk, see PartitionsSpec	`dynamic` if `forceGuaranteedRollup` = false, `hashed` if `forceGuaranteedRollup` = true	no
indexSpec	Defines segment storage format options to be used at indexing time, see IndexSpec	null	no
indexSpecForIntermediatePersists	Defines segment storage format options to be used at indexing time for intermediate persisted temporary segments. this can be used to disable dimension/metric compression on intermediate segments to reduce memory required for final merging. however, disabling compression on intermediate segments might increase page cache use while they are used before getting merged into final segment published, see IndexSpec for possible values.	same as indexSpec	no
maxPendingPersists	Maximum number of persists that can be pending but not started. If this limit would be exceeded by a new intermediate persist, ingestion will block until the currently-running persist finishes. Maximum heap memory usage for indexing scales with maxRowsInMemory * (2 + maxPendingPersists).	0 (meaning one persist can be running concurrently with ingestion, and none can be queued up)	no
forceGuaranteedRollup	Forces guaranteeing the perfect rollup. The perfect rollup optimizes the total size of generated segments and querying time while indexing time will be increased. If this is set to true, the index task will read the entire input data twice: one for finding the optimal number of partitions per time chunk and one for generating segments. Note that the result segments would be hash-partitioned. This flag cannot be used with `appendToExisting` of IOConfig. For more details, see the below Segment pushing modes section.	false	no
reportParseExceptions	DEPRECATED. If true, exceptions encountered during parsing will be thrown and will halt ingestion; if false, unparseable rows and fields will be skipped. Setting `reportParseExceptions` to true will override existing configurations for `maxParseExceptions` and `maxSavedParseExceptions`, setting `maxParseExceptions` to 0 and limiting `maxSavedParseExceptions` to no more than 1.	false	no
pushTimeout	Milliseconds to wait for pushing segments. It must be >= 0, where 0 means to wait forever.	0	no
segmentWriteOutMediumFactory	Segment write-out medium to use when creating segments. See SegmentWriteOutMediumFactory.	Not specified, the value from `druid.peon.defaultSegmentWriteOutMediumFactory.type` is used	no
logParseExceptions	If true, log an error message when a parsing exception occurs, containing information about the row where the error occurred.	false	no
maxParseExceptions	The maximum number of parse exceptions that can occur before the task halts ingestion and fails. Overridden if `reportParseExceptions` is set.	unlimited	no
maxSavedParseExceptions	When a parse exception occurs, Druid can keep track of the most recent parse exceptions. "maxSavedParseExceptions" limits how many exception instances will be saved. These saved exceptions will be made available after the task finishes in the task completion report. Overridden if `reportParseExceptions` is set.	0	no

`partitionsSpec`

PartitionsSpec is to describe the secondary partitioning method. You should use different partitionsSpec depending on the rollup mode you want. For perfect rollup, you should use hashed.

property	description	default	required?
type	This should always be `hashed`	none	yes
maxRowsPerSegment	Used in sharding. Determines how many rows are in each segment.	5000000	no
numShards	Directly specify the number of shards to create. If this is specified and `intervals` is specified in the `granularitySpec`, the index task can skip the determine intervals/partitions pass through the data. `numShards` cannot be specified if `maxRowsPerSegment` is set.	null	no
partitionDimensions	The dimensions to partition on. Leave blank to select all dimensions.	null	no

For best-effort rollup, you should use dynamic.

property	description	default	required?
type	This should always be `dynamic`	none	yes
maxRowsPerSegment	Used in sharding. Determines how many rows are in each segment.	5000000	no
maxTotalRows	Total number of rows in segments waiting for being pushed.	20000000	no

`segmentWriteOutMediumFactory`

Field	Type	Description	Required
type	String	See Additional Peon Configuration: SegmentWriteOutMediumFactory for explanation and available options.	yes

Segment pushing modes

While ingesting data using the Index task, it creates segments from the input data and pushes them. For segment pushing, the Index task supports two segment pushing modes, i.e., bulk pushing mode and incremental pushing mode for perfect rollup and best-effort rollup, respectively.

In the bulk pushing mode, every segment is pushed at the very end of the index task. Until then, created segments are stored in the memory and local storage of the process running the index task. As a result, this mode might cause a problem due to limited storage capacity, and is not recommended to use in production.

On the contrary, in the incremental pushing mode, segments are incrementally pushed, that is they can be pushed in the middle of the index task. More precisely, the index task collects data and stores created segments in the memory and disks of the process running that task until the total number of collected rows exceeds maxTotalRows. Once it exceeds, the index task immediately pushes all segments created until that moment, cleans all pushed segments up, and continues to ingest remaining data.

To enable bulk pushing mode, forceGuaranteedRollup should be set in the TuningConfig. Note that this option cannot be used with appendToExisting of IOConfig.

Input Sources

The input source is the place to define from where your index task reads data. Only the native Parallel task and Simple task support the input source.

S3 Input Source

You need to include the druid-s3-extensions as an extension to use the S3 input source.

The S3 input source is to support reading objects directly from S3. Objects can be specified either via a list of S3 URI strings or a list of S3 location prefixes, which will attempt to list the contents and ingest all objects contained in the locations. The S3 input source is splittable and can be used by the Parallel task, where each worker task of index_parallel will read one or multiple objects.

Sample specs:

...
    "ioConfig": {
      "type": "index_parallel",
      "inputSource": {
        "type": "s3",
        "uris": ["s3://foo/bar/file.json", "s3://bar/foo/file2.json"]
      },
      "inputFormat": {
        "type": "json"
      },
      ...
    },
...

...
    "ioConfig": {
      "type": "index_parallel",
      "inputSource": {
        "type": "s3",
        "prefixes": ["s3://foo/bar", "s3://bar/foo"]
      },
      "inputFormat": {
        "type": "json"
      },
      ...
    },
...

...
    "ioConfig": {
      "type": "index_parallel",
      "inputSource": {
        "type": "s3",
        "objects": [
          { "bucket": "foo", "path": "bar/file1.json"},
          { "bucket": "bar", "path": "foo/file2.json"}
        ]
      },
      "inputFormat": {
        "type": "json"
      },
      ...
    },
...

property	description	default	required?
type	This should be `s3`.	None	yes
uris	JSON array of URIs where S3 objects to be ingested are located.	None	`uris` or `prefixes` or `objects` must be set
prefixes	JSON array of URI prefixes for the locations of S3 objects to be ingested. Empty objects starting with one of the given prefixes will be skipped.	None	`uris` or `prefixes` or `objects` must be set
objects	JSON array of S3 Objects to be ingested.	None	`uris` or `prefixes` or `objects` must be set
properties	Properties Object for overriding the default S3 configuration. See below for more information.	None	No (defaults will be used if not given)

Note that the S3 input source will skip all empty objects only when prefixes is specified.

S3 Object:

property	description	default	required?
bucket	Name of the S3 bucket	None	yes
path	The path where data is located.	None	yes

Properties Object:

property	description	default	required?
accessKeyId	The Password Provider or plain text string of this S3 InputSource's access key	None	yes if secretAccessKey is given
secretAccessKey	The Password Provider or plain text string of this S3 InputSource's secret key	None	yes if accessKeyId is given

Note : If accessKeyId and secretAccessKey are not given, the default S3 credentials provider chain is used.

Google Cloud Storage Input Source

You need to include the druid-google-extensions as an extension to use the Google Cloud Storage input source.

The Google Cloud Storage input source is to support reading objects directly from Google Cloud Storage. Objects can be specified as list of Google Cloud Storage URI strings. The Google Cloud Storage input source is splittable and can be used by the Parallel task, where each worker task of index_parallel will read one or multiple objects.

Sample specs:

...
    "ioConfig": {
      "type": "index_parallel",
      "inputSource": {
        "type": "google",
        "uris": ["gs://foo/bar/file.json", "gs://bar/foo/file2.json"]
      },
      "inputFormat": {
        "type": "json"
      },
      ...
    },
...

...
    "ioConfig": {
      "type": "index_parallel",
      "inputSource": {
        "type": "google",
        "prefixes": ["gs://foo/bar", "gs://bar/foo"]
      },
      "inputFormat": {
        "type": "json"
      },
      ...
    },
...

...
    "ioConfig": {
      "type": "index_parallel",
      "inputSource": {
        "type": "google",
        "objects": [
          { "bucket": "foo", "path": "bar/file1.json"},
          { "bucket": "bar", "path": "foo/file2.json"}
        ]
      },
      "inputFormat": {
        "type": "json"
      },
      ...
    },
...

property	description	default	required?
type	This should be `google`.	None	yes
uris	JSON array of URIs where Google Cloud Storage objects to be ingested are located.	None	`uris` or `prefixes` or `objects` must be set
prefixes	JSON array of URI prefixes for the locations of Google Cloud Storage objects to be ingested. Empty objects starting with one of the given prefixes will be skipped.	None	`uris` or `prefixes` or `objects` must be set
objects	JSON array of Google Cloud Storage objects to be ingested.	None	`uris` or `prefixes` or `objects` must be set

Note that the Google Cloud Storage input source will skip all empty objects only when prefixes is specified.

Google Cloud Storage object:

property	description	default	required?
bucket	Name of the Google Cloud Storage bucket	None	yes
path	The path where data is located.	None	yes

Azure Input Source

You need to include the druid-azure-extensions as an extension to use the Azure input source.

The Azure input source is to support reading objects directly from Azure Blob store. Objects can be specified as list of Azure Blob store URI strings. The Azure input source is splittable and can be used by the Parallel task, where each worker task of index_parallel will read a single object.

Sample specs:

...
    "ioConfig": {
      "type": "index_parallel",
      "inputSource": {
        "type": "azure",
        "uris": ["azure://container/prefix1/file.json", "azure://container/prefix2/file2.json"]
      },
      "inputFormat": {
        "type": "json"
      },
      ...
    },
...

...
    "ioConfig": {
      "type": "index_parallel",
      "inputSource": {
        "type": "azure",
        "prefixes": ["azure://container/prefix1", "azure://container/prefix2"]
      },
      "inputFormat": {
        "type": "json"
      },
      ...
    },
...

...
    "ioConfig": {
      "type": "index_parallel",
      "inputSource": {
        "type": "azure",
        "objects": [
          { "bucket": "container", "path": "prefix1/file1.json"},
          { "bucket": "container", "path": "prefix2/file2.json"}
        ]
      },
      "inputFormat": {
        "type": "json"
      },
      ...
    },
...

property	description	default	required?
type	This should be `azure`.	None	yes
uris	JSON array of URIs where Azure Blob objects to be ingested are located. Should be in form "azure://<container>/<path-to-file>"	None	`uris` or `prefixes` or `objects` must be set
prefixes	JSON array of URI prefixes for the locations of Azure Blob objects to be ingested. Should be in the form "azure://<container>/<prefix>". Empty objects starting with one of the given prefixes will be skipped.	None	`uris` or `prefixes` or `objects` must be set
objects	JSON array of Azure Blob objects to be ingested.	None	`uris` or `prefixes` or `objects` must be set

Note that the Azure input source will skip all empty objects only when prefixes is specified.

Azure Blob object:

property	description	default	required?
bucket	Name of the Azure Blob Storage container	None	yes
path	The path where data is located.	None	yes

HDFS Input Source

You need to include the druid-hdfs-storage as an extension to use the HDFS input source.

The HDFS input source is to support reading files directly from HDFS storage. File paths can be specified as an HDFS URI string or a list of HDFS URI strings. The HDFS input source is splittable and can be used by the Parallel task, where each worker task of index_parallel will read one or multiple files.

Sample specs:

...
    "ioConfig": {
      "type": "index_parallel",
      "inputSource": {
        "type": "hdfs",
        "paths": "hdfs://foo/bar/", "hdfs://bar/foo"
      },
      "inputFormat": {
        "type": "json"
      },
      ...
    },
...

...
    "ioConfig": {
      "type": "index_parallel",
      "inputSource": {
        "type": "hdfs",
        "paths": ["hdfs://foo/bar", "hdfs://bar/foo"]
      },
      "inputFormat": {
        "type": "json"
      },
      ...
    },
...

...
    "ioConfig": {
      "type": "index_parallel",
      "inputSource": {
        "type": "hdfs",
        "paths": "hdfs://foo/bar/file.json", "hdfs://bar/foo/file2.json"
      },
      "inputFormat": {
        "type": "json"
      },
      ...
    },
...

...
    "ioConfig": {
      "type": "index_parallel",
      "inputSource": {
        "type": "hdfs",
        "paths": ["hdfs://foo/bar/file.json", "hdfs://bar/foo/file2.json"]
      },
      "inputFormat": {
        "type": "json"
      },
      ...
    },
...

property	description	default	required?
type	This should be `hdfs`.	None	yes
paths	HDFS paths. Can be either a JSON array or comma-separated string of paths. Wildcards like `*` are supported in these paths. Empty files located under one of the given paths will be skipped.	None	yes

You can also ingest from cloud storage using the HDFS input source. However, if you want to read from AWS S3 or Google Cloud Storage, consider using the S3 input source or the Google Cloud Storage input source instead.

HTTP Input Source

The HTTP input source is to support reading files directly from remote sites via HTTP. The HTTP input source is splittable and can be used by the Parallel task, where each worker task of index_parallel will read only one file.

Sample specs:

...
    "ioConfig": {
      "type": "index_parallel",
      "inputSource": {
        "type": "http",
        "uris": ["http://example.com/uri1", "http://example2.com/uri2"]
      },
      "inputFormat": {
        "type": "json"
      },
      ...
    },
...

Example with authentication fields using the DefaultPassword provider (this requires the password to be in the ingestion spec):

...
    "ioConfig": {
      "type": "index_parallel",
      "inputSource": {
        "type": "http",
        "uris": ["http://example.com/uri1", "http://example2.com/uri2"],
        "httpAuthenticationUsername": "username",
        "httpAuthenticationPassword": "password123"
      },
      "inputFormat": {
        "type": "json"
      },
      ...
    },
...

You can also use the other existing Druid PasswordProviders. Here is an example using the EnvironmentVariablePasswordProvider:

...
    "ioConfig": {
      "type": "index_parallel",
      "inputSource": {
        "type": "http",
        "uris": ["http://example.com/uri1", "http://example2.com/uri2"],
        "httpAuthenticationUsername": "username",
        "httpAuthenticationPassword": {
          "type": "environment",
          "variable": "HTTP_INPUT_SOURCE_PW"
        }
      },
      "inputFormat": {
        "type": "json"
      },
      ...
    },
...
}

property	description	default	required?
type	This should be `http`	None	yes
uris	URIs of the input files.	None	yes
httpAuthenticationUsername	Username to use for authentication with specified URIs. Can be optionally used if the URIs specified in the spec require a Basic Authentication Header.	None	no
httpAuthenticationPassword	PasswordProvider to use with specified URIs. Can be optionally used if the URIs specified in the spec require a Basic Authentication Header.	None	no

Inline Input Source

The Inline input source can be used to read the data inlined in its own spec. It can be used for demos or for quickly testing out parsing and schema.

Sample spec:

...
    "ioConfig": {
      "type": "index_parallel",
      "inputSource": {
        "type": "inline",
        "data": "0,values,formatted\n1,as,CSV"
      },
      "inputFormat": {
        "type": "csv"
      },
      ...
    },
...

property	description	required?
type	This should be "inline".	yes
data	Inlined data to ingest.	yes

Local Input Source

The Local input source is to support reading files directly from local storage, and is mainly intended for proof-of-concept testing. The Local input source is splittable and can be used by the Parallel task, where each worker task of index_parallel will read one or multiple files.

Sample spec:

...
    "ioConfig": {
      "type": "index_parallel",
      "inputSource": {
        "type": "local",
        "filter" : "*.csv",
        "baseDir": "/data/directory",
        "files": ["/bar/foo", "/foo/bar"]
      },
      "inputFormat": {
        "type": "csv"
      },
      ...
    },
...

property	description	required?
type	This should be "local".	yes
filter	A wildcard filter for files. See here for more information.	yes if `baseDir` is specified
baseDir	Directory to search recursively for files to be ingested. Empty files under the `baseDir` will be skipped.	At least one of `baseDir` or `files` should be specified
files	File paths to ingest. Some files can be ignored to avoid ingesting duplicate files if they are located under the specified `baseDir`. Empty files will be skipped.	At least one of `baseDir` or `files` should be specified

Druid Input Source

The Druid input source is to support reading data directly from existing Druid segments, potentially using a new schema and changing the name, dimensions, metrics, rollup, etc. of the segment. The Druid input source is splittable and can be used by the Parallel task. This input source has a fixed input format for reading from Druid segments; no inputFormat field needs to be specified in the ingestion spec when using this input source.

property	description	required?
type	This should be "druid".	yes
dataSource	A String defining the Druid datasource to fetch rows from	yes
interval	A String representing an ISO-8601 interval, which defines the time range to fetch the data over.	yes
dimensions	A list of Strings containing the names of dimension columns to select from the Druid datasource. If the list is empty, no dimensions are returned. If null, all dimensions are returned.	no
metrics	The list of Strings containing the names of metric columns to select. If the list is empty, no metrics are returned. If null, all metrics are returned.	no
filter	See Filters. Only rows that match the filter, if specified, will be returned.	no

A minimal example DruidInputSource spec is shown below:

...
    "ioConfig": {
      "type": "index_parallel",
      "inputSource": {
        "type": "druid",
        "dataSource": "wikipedia",
        "interval": "2013-01-01/2013-01-02"
      }
      ...
    },
...

The spec above will read all existing dimension and metric columns from the wikipedia datasource, including all rows with a timestamp (the __time column) within the interval 2013-01-01/2013-01-02.

A spec that applies a filter and reads a subset of the original datasource's columns is shown below.

...
    "ioConfig": {
      "type": "index_parallel",
      "inputSource": {
        "type": "druid",
        "dataSource": "wikipedia",
        "interval": "2013-01-01/2013-01-02",
        "dimensions": [
          "page",
          "user"
        ],
        "metrics": [
          "added"
        ],
        "filter": {
          "type": "selector",
          "dimension": "page",
          "value": "Druid"
        }
      }
      ...
    },
...

This spec above will only return the page, user dimensions and added metric. Only rows where page = Druid will be returned.

SQL Input Source

The SQL input source is used to read data directly from RDBMS. The SQL input source is splittable and can be used by the Parallel task, where each worker task will read from one SQL query from the list of queries. Since this input source has a fixed input format for reading events, no inputFormat field needs to be specified in the ingestion spec when using this input source. Please refer to the Recommended practices section below before using this input source.

property	description	required?
type	This should be "sql".	Yes
database	Specifies the database connection details. The database type corresponds to the extension that supplies the `connectorConfig` support and this extension must be loaded into Druid. For database types `mysql` and `postgresql`, the `connectorConfig` support is provided by mysql-metadata-storage and postgresql-metadata-storage extensions respectively.	Yes
foldCase	Toggle case folding of database column names. This may be enabled in cases where the database returns case insensitive column names in query results.	No
sqls	List of SQL queries where each SQL query would retrieve the data to be indexed.	Yes

An example SqlInputSource spec is shown below:

...
    "ioConfig": {
      "type": "index_parallel",
      "inputSource": {
        "type": "sql",
        "database": {
            "type": "mysql",
            "connectorConfig": {
                "connectURI": "jdbc:mysql://host:port/schema",
                "user": "user",
                "password": "password"
            }
        },
        "sqls": ["SELECT * FROM table1 WHERE timestamp BETWEEN '2013-01-01 00:00:00' AND '2013-01-01 11:59:59'", "SELECT * FROM table2 WHERE timestamp BETWEEN '2013-01-01 00:00:00' AND '2013-01-01 11:59:59'"]
      }
    },
...

The spec above will read all events from two separate SQLs for the interval 2013-01-01/2013-01-02. Each of the SQL queries will be run in its own sub-task and thus for the above example, there would be two sub-tasks.

Recommended practices

Compared to the other native batch InputSources, SQL InputSource behaves differently in terms of reading the input data and so it would be helpful to consider the following points before using this InputSource in a production environment:

During indexing, each sub-task would execute one of the SQL queries and the results are stored locally on disk. The sub-tasks then proceed to read the data from these local input files and generate segments. Presently, there isn’t any restriction on the size of the generated files and this would require the MiddleManagers or Indexers to have sufficient disk capacity based on the volume of data being indexed.
Filtering the SQL queries based on the intervals specified in the granularitySpec can avoid unwanted data being retrieved and stored locally by the indexing sub-tasks. For example, if the intervals specified in the granularitySpec is ["2013-01-01/2013-01-02"] and the SQL query is SELECT * FROM table1, SqlInputSource will read all the data for table1 based on the query, even though only data between the intervals specified will be indexed into Druid.
Pagination may be used on the SQL queries to ensure that each query pulls a similar amount of data, thereby improving the efficiency of the sub-tasks.
Similar to file-based input formats, any updates to existing data will replace the data in segments specific to the intervals specified in the granularitySpec.

Firehoses (Deprecated)

Firehoses are deprecated in 0.17.0. It's highly recommended to use the Input source instead. There are several firehoses readily available in Druid, some are meant for examples, others can be used directly in a production environment.

StaticS3Firehose

You need to include the druid-s3-extensions as an extension to use the StaticS3Firehose.

This firehose ingests events from a predefined list of S3 objects. This firehose is splittable and can be used by the Parallel task. Since each split represents an object in this firehose, each worker task of index_parallel will read an object.

Sample spec:

"firehose" : {
    "type" : "static-s3",
    "uris": ["s3://foo/bar/file.gz", "s3://bar/foo/file2.gz"]
}

This firehose provides caching and prefetching features. In the Simple task, a firehose can be read twice if intervals or shardSpecs are not specified, and, in this case, caching can be useful. Prefetching is preferred when direct scan of objects is slow. Note that prefetching or caching isn't that useful in the Parallel task.

property	description	default	required?
type	This should be `static-s3`.	None	yes
uris	JSON array of URIs where s3 files to be ingested are located.	None	`uris` or `prefixes` must be set
prefixes	JSON array of URI prefixes for the locations of s3 files to be ingested.	None	`uris` or `prefixes` must be set
maxCacheCapacityBytes	Maximum size of the cache space in bytes. 0 means disabling cache. Cached files are not removed until the ingestion task completes.	1073741824	no
maxFetchCapacityBytes	Maximum size of the fetch space in bytes. 0 means disabling prefetch. Prefetched files are removed immediately once they are read.	1073741824	no
prefetchTriggerBytes	Threshold to trigger prefetching s3 objects.	maxFetchCapacityBytes / 2	no
fetchTimeout	Timeout for fetching an s3 object.	60000	no
maxFetchRetry	Maximum retry for fetching an s3 object.	3	no

StaticGoogleBlobStoreFirehose

You need to include the druid-google-extensions as an extension to use the StaticGoogleBlobStoreFirehose.

This firehose ingests events, similar to the StaticS3Firehose, but from an Google Cloud Store.

As with the S3 blobstore, it is assumed to be gzipped if the extension ends in .gz

This firehose is splittable and can be used by the Parallel task. Since each split represents an object in this firehose, each worker task of index_parallel will read an object.

Sample spec:

"firehose" : {
    "type" : "static-google-blobstore",
    "blobs": [
        {
          "bucket": "foo",
          "path": "/path/to/your/file.json"
        },
        {
          "bucket": "bar",
          "path": "/another/path.json"
        }
    ]
}

property	description	default	required?
type	This should be `static-google-blobstore`.	None	yes
blobs	JSON array of Google Blobs.	None	yes
maxCacheCapacityBytes	Maximum size of the cache space in bytes. 0 means disabling cache. Cached files are not removed until the ingestion task completes.	1073741824	no
maxFetchCapacityBytes	Maximum size of the fetch space in bytes. 0 means disabling prefetch. Prefetched files are removed immediately once they are read.	1073741824	no
prefetchTriggerBytes	Threshold to trigger prefetching Google Blobs.	maxFetchCapacityBytes / 2	no
fetchTimeout	Timeout for fetching a Google Blob.	60000	no
maxFetchRetry	Maximum retry for fetching a Google Blob.	3	no

Google Blobs:

property	description	default	required?
bucket	Name of the Google Cloud bucket	None	yes
path	The path where data is located.	None	yes

HDFSFirehose

You need to include the druid-hdfs-storage as an extension to use the HDFSFirehose.

This firehose ingests events from a predefined list of files from the HDFS storage. This firehose is splittable and can be used by the Parallel task. Since each split represents an HDFS file, each worker task of index_parallel will read files.

Sample spec:

"firehose" : {
    "type" : "hdfs",
    "paths": "/foo/bar,/foo/baz"
}

This firehose provides caching and prefetching features. During native batch indexing, a firehose can be read twice if intervals are not specified, and, in this case, caching can be useful. Prefetching is preferred when direct scanning of files is slow. Note that prefetching or caching isn't that useful in the Parallel task.

Property	Description	Default
type	This should be `hdfs`.	none (required)
paths	HDFS paths. Can be either a JSON array or comma-separated string of paths. Wildcards like `*` are supported in these paths.	none (required)
maxCacheCapacityBytes	Maximum size of the cache space in bytes. 0 means disabling cache. Cached files are not removed until the ingestion task completes.	1073741824
maxFetchCapacityBytes	Maximum size of the fetch space in bytes. 0 means disabling prefetch. Prefetched files are removed immediately once they are read.	1073741824
prefetchTriggerBytes	Threshold to trigger prefetching files.	maxFetchCapacityBytes / 2
fetchTimeout	Timeout for fetching each file.	60000
maxFetchRetry	Maximum number of retries for fetching each file.	3

LocalFirehose

This Firehose can be used to read the data from files on local disk, and is mainly intended for proof-of-concept testing, and works with string typed parsers. This Firehose is splittable and can be used by native parallel index tasks. Since each split represents a file in this Firehose, each worker task of index_parallel will read a file. A sample local Firehose spec is shown below:

{
    "type": "local",
    "filter" : "*.csv",
    "baseDir": "/data/directory"
}

property	description	required?
type	This should be "local".	yes
filter	A wildcard filter for files. See here for more information.	yes
baseDir	directory to search recursively for files to be ingested.	yes

HttpFirehose

This Firehose can be used to read the data from remote sites via HTTP, and works with string typed parsers. This Firehose is splittable and can be used by native parallel index tasks. Since each split represents a file in this Firehose, each worker task of index_parallel will read a file. A sample HTTP Firehose spec is shown below:

{
    "type": "http",
    "uris": ["http://example.com/uri1", "http://example2.com/uri2"]
}

The below configurations can be optionally used if the URIs specified in the spec require a Basic Authentication Header. Omitting these fields from your spec will result in HTTP requests with no Basic Authentication Header.

property	description	default
httpAuthenticationUsername	Username to use for authentication with specified URIs	None
httpAuthenticationPassword	PasswordProvider to use with specified URIs	None

Example with authentication fields using the DefaultPassword provider (this requires the password to be in the ingestion spec):

{
    "type": "http",
    "uris": ["http://example.com/uri1", "http://example2.com/uri2"],
    "httpAuthenticationUsername": "username",
    "httpAuthenticationPassword": "password123"
}

You can also use the other existing Druid PasswordProviders. Here is an example using the EnvironmentVariablePasswordProvider:

{
    "type": "http",
    "uris": ["http://example.com/uri1", "http://example2.com/uri2"],
    "httpAuthenticationUsername": "username",
    "httpAuthenticationPassword": {
        "type": "environment",
        "variable": "HTTP_FIREHOSE_PW"
    }
}

The below configurations can optionally be used for tuning the Firehose performance. Note that prefetching or caching isn't that useful in the Parallel task.

property	description	default
maxCacheCapacityBytes	Maximum size of the cache space in bytes. 0 means disabling cache. Cached files are not removed until the ingestion task completes.	1073741824
maxFetchCapacityBytes	Maximum size of the fetch space in bytes. 0 means disabling prefetch. Prefetched files are removed immediately once they are read.	1073741824
prefetchTriggerBytes	Threshold to trigger prefetching HTTP objects.	maxFetchCapacityBytes / 2
fetchTimeout	Timeout for fetching an HTTP object.	60000
maxFetchRetry	Maximum retries for fetching an HTTP object.	3

IngestSegmentFirehose

This Firehose can be used to read the data from existing druid segments, potentially using a new schema and changing the name, dimensions, metrics, rollup, etc. of the segment. This Firehose is splittable and can be used by native parallel index tasks. This firehose will accept any type of parser, but will only utilize the list of dimensions and the timestamp specification. A sample ingest Firehose spec is shown below:

{
    "type": "ingestSegment",
    "dataSource": "wikipedia",
    "interval": "2013-01-01/2013-01-02"
}

property	description	required?
type	This should be "ingestSegment".	yes
dataSource	A String defining the data source to fetch rows from, very similar to a table in a relational database	yes
interval	A String representing the ISO-8601 interval. This defines the time range to fetch the data over.	yes
dimensions	The list of dimensions to select. If left empty, no dimensions are returned. If left null or not defined, all dimensions are returned.	no
metrics	The list of metrics to select. If left empty, no metrics are returned. If left null or not defined, all metrics are selected.	no
filter	See Filters	no
maxInputSegmentBytesPerTask	Deprecated. Use Segments Split Hint Spec instead. When used with the native parallel index task, the maximum number of bytes of input segments to process in a single task. If a single segment is larger than this number, it will be processed by itself in a single task (input segments are never split across tasks). Defaults to 150MB.	no

SqlFirehose

This Firehose can be used to ingest events residing in an RDBMS. The database connection information is provided as part of the ingestion spec. For each query, the results are fetched locally and indexed. If there are multiple queries from which data needs to be indexed, queries are prefetched in the background, up to maxFetchCapacityBytes bytes. This Firehose is splittable and can be used by native parallel index tasks. This firehose will accept any type of parser, but will only utilize the list of dimensions and the timestamp specification. See the extension documentation for more detailed ingestion examples.

Requires one of the following extensions:

{
    "type": "sql",
    "database": {
        "type": "mysql",
        "connectorConfig": {
            "connectURI": "jdbc:mysql://host:port/schema",
            "user": "user",
            "password": "password"
        }
     },
    "sqls": ["SELECT * FROM table1", "SELECT * FROM table2"]
}

property	description	default	required?
type	This should be "sql".		Yes
database	Specifies the database connection details.		Yes
maxCacheCapacityBytes	Maximum size of the cache space in bytes. 0 means disabling cache. Cached files are not removed until the ingestion task completes.	1073741824	No
maxFetchCapacityBytes	Maximum size of the fetch space in bytes. 0 means disabling prefetch. Prefetched files are removed immediately once they are read.	1073741824	No
prefetchTriggerBytes	Threshold to trigger prefetching SQL result objects.	maxFetchCapacityBytes / 2	No
fetchTimeout	Timeout for fetching the result set.	60000	No
foldCase	Toggle case folding of database column names. This may be enabled in cases where the database returns case insensitive column names in query results.	false	No
sqls	List of SQL queries where each SQL query would retrieve the data to be indexed.		Yes

Database

property	description	default	required?
type	The type of database to query. Valid values are `mysql` and `postgresql`_		Yes
connectorConfig	Specify the database connection properties via `connectURI`, `user` and `password`		Yes

InlineFirehose

This Firehose can be used to read the data inlined in its own spec. It can be used for demos or for quickly testing out parsing and schema, and works with string typed parsers. A sample inline Firehose spec is shown below:

{
    "type": "inline",
    "data": "0,values,formatted\n1,as,CSV"
}

property	description	required?
type	This should be "inline".	yes
data	Inlined data to ingest.	yes

CombiningFirehose

This Firehose can be used to combine and merge data from a list of different Firehoses.

{
    "type": "combining",
    "delegates": [ { firehose1 }, { firehose2 }, ... ]
}

property	description	required?
type	This should be "combining"	yes
delegates	List of Firehoses to combine data from	yes

77 KiB Raw Blame History Unescape Escape

Tutorial

Parallel task

Task syntax

dataSchema

ioConfig

tuningConfig

Split Hint Spec

Size-based Split Hint Spec

Segments Split Hint Spec

partitionsSpec

Dynamic partitioning

Hash-based partitioning

Single-dimension range partitioning

HTTP status endpoints

Capacity planning

Simple task

Task syntax

dataSchema

ioConfig

tuningConfig

partitionsSpec

segmentWriteOutMediumFactory

Segment pushing modes

Input Sources

S3 Input Source

Google Cloud Storage Input Source

Azure Input Source

HDFS Input Source

HTTP Input Source

Inline Input Source

Local Input Source

Druid Input Source

SQL Input Source

Firehoses (Deprecated)

StaticS3Firehose

StaticGoogleBlobStoreFirehose

HDFSFirehose

LocalFirehose

HttpFirehose

IngestSegmentFirehose

SqlFirehose

Database

InlineFirehose

CombiningFirehose

77 KiB

Raw Blame History

`dataSchema`

`ioConfig`

`tuningConfig`

`partitionsSpec`

`dataSchema`

`ioConfig`

`tuningConfig`

`partitionsSpec`

`segmentWriteOutMediumFactory`