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Use LightIngest to ingest data into Azure Data Explorer

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LightIngest is a command-line utility for ad-hoc data ingestion into Azure Data Explorer. The utility can pull source data from a local folder or from an Azure blob storage container. LightIngest is most useful when you want to ingest a large amount of data, because there is no time constraint on ingestion duration. It's also useful when you want to later query records according to the time they were created, and not the time they were ingested.

To auto-generate a LightIngest command, see Use ingestion wizard for one-time ingestion of historical data with LightIngest.

Prerequisites

Install LightIngest

  1. Navigate to the location on your computer where you downloaded LightIngest.
  2. Using WinRAR, extract the tools directory to your computer.

Run LightIngest

  1. Navigate to the extracted tools directory on your computer.

  2. Delete the existing location information from the location bar.

    Delete existing location information for LightIngest in Azure Data Explorer.

  3. Enter cmd and press Enter.

  4. At the command prompt, enter LightIngest.exe followed by the relevant command-line argument.

    Tip

    For a list of supported command-line arguments, enter LightIngest.exe /help.

    Command line help for LightIngest.

  5. Enter ingest- followed by the connection string to the Azure Data Explorer cluster that will manage the ingestion. Enclose the connection string in double quotes and follow the Kusto connection strings specification.

    For example:

    LightIngest.exe "https://ingest-{Cluster name and region}.kusto.windows.net;Fed=True" -db:{Database} -table:Trips -source:"https://{Account}.blob.core.windows.net/{ROOT_CONTAINER};{StorageAccountKey}" -pattern:"*.csv.gz" -format:csv -limit:2 -ignoreFirst:true -cr:10.0 -dontWait:true

Recommendations

  • The recommended method is for LightIngest to work with the ingestion endpoint at https://ingest-{yourClusterNameAndRegion}.kusto.windows.net. This way, the Azure Data Explorer service can manage the ingestion load, and you can easily recover from transient errors. However, you can also configure LightIngest to work directly with the engine endpoint (https://{yourClusterNameAndRegion}.kusto.windows.net).

    Note

    If you ingest directly with the engine endpoint, you don't need to include ingest-. However, there won't be a DM feature to protect the engine and improve the ingestion success rate.

  • For optimal ingestion performance, the raw data size is needed so LightIngest can estimate the uncompressed size of local files. However, LightIngest might not be able to correctly estimate the raw size of compressed blobs without first downloading them. Therefore, when ingesting compressed blobs, set the rawSizeBytes property on the blob metadata to uncompressed data size in bytes.

Command-line arguments

Argument name Type Description Mandatory/Optional
string Azure Data Explorer Connection String specifying the Kusto endpoint that will handle the ingestion. Should be enclosed in double quotes Mandatory
-database, -db string Target Azure Data Explorer database name Optional
-table string Target Azure Data Explorer table name Mandatory
-sourcePath, -source string Path to source files or root URI of the blob container. If the data is in blobs, must contain storage account key or SAS. Recommended to enclose in double quotes Mandatory
-prefix string When the source data to ingest resides on blob storage, this URL prefix is shared by all blobs, excluding the container name.
For example, if the data is in MyContainer/Dir1/Dir2, then the prefix should be Dir1/Dir2. Enclosing in double quotes is recommended		 Optional
-pattern string Pattern by which source files/blobs are picked. Supports wildcards. For example, "*.csv". Recommended to enclose in double quotes Optional
-zipPattern string Regular expression to use when selecting which files in a ZIP archive to ingest.
All other files in the archive will be ignored. For example, "*.csv". It's recommended to surround it in double quotes		 Optional
-format, -f string Source data format. Must be one of the supported formats Optional
-ingestionMappingPath, -mappingPath string Path to local file for ingestion column mapping. Mandatory for Json and Avro formats. See data mappings Optional
-ingestionMappingRef, -mappingRef string Name of an ingestion column mapping that was previously created on the table. Mandatory for Json and Avro formats. See data mappings Optional
-creationTimePattern string When set, is used to extract the CreationTime property from the file or blob path. See How to ingest data using CreationTime Optional
-ignoreFirstRow, -ignoreFirst bool If set, the first record of each file/blob is ignored (for example, if the source data has headers) Optional
-tag string Tags to associate with the ingested data. Multiple occurrences are permitted Optional
-dontWait bool If set to 'true', doesn't wait for ingestion completion. Useful when ingesting large amounts of files/blobs Optional
-compression, -cr double Compression ratio hint. Useful when ingesting compressed files/blobs to help Azure Data Explorer assess the raw data size. Calculated as original size divided by compressed size Optional
-limit , -l integer If set, limits the ingestion to first N files Optional
-listOnly, -list bool If set, only displays the items that would have been selected for ingestion Optional
-ingestTimeout integer Timeout in minutes for all ingest operations completion. Defaults to 60 Optional
-forceSync bool If set, forces synchronous ingestion. Defaults to false Optional
-dataBatchSize integer Sets the total size limit (MB, uncompressed) of each ingest operation Optional
-filesInBatch integer Sets the file/blob count limit of each ingest operation Optional
-devTracing, -trace string If set, diagnostic logs are written to a local directory (by default, RollingLogs in the current directory, or can be modified by setting the switch value) Optional

Azure blob-specific capabilities

When used with Azure blobs, LightIngest will use certain blob metadata properties to augment the ingestion process.

Metadata property Usage
rawSizeBytes, kustoUncompressedSizeBytes If set, will be interpreted as the uncompressed data size
kustoCreationTime, kustoCreationTimeUtc Interpreted as UTC timestamp. If set, will be used to override the creation time in Kusto. Useful for backfilling scenarios

Usage examples

How to ingest data using CreationTime

When you load historical data from existing system to Azure Data Explorer, all records receive the same the ingestion date. To enable partitioning your data by creation time and not ingestion time, you can use the -creationTimePattern argument. The -creationTimePattern argument extracts the CreationTime property from the file or blob path. The pattern doesn't need to reflect the entire item path, just the section enclosing the timestamp you want to use.

The argument values must include:

  • Constant text immediately preceding the timestamp format, enclosed in single quotes (prefix)
  • The timestamp format, in standard .NET DateTime notation
  • Constant text immediately following the timestamp (suffix).

Important

When specifying that the creation time should be overridden, make sure the Lookback property in the target table's effective Extents merge policy is aligned with the values in your file or blob paths.

Examples

  • A blob name that contains the datetime as follows: historicalvalues19840101.parquet (the timestamp is four digits for the year, two digits for the month, and two digits for the day of month),

    The value for -creationTimePattern argument is part of the filename: "'historicalvalues'yyyyMMdd'.parquet'"

    LightIngest.exe "https://ingest-{Cluster name and region}.kusto.windows.net;Fed=True" -db:{Database} -table:Trips -source:"https://{Account}.blob.core.windows.net/{ROOT_CONTAINER};{StorageAccountKey}" -creationTimePattern:"'historicalvalues'yyyyMMdd'.parquet'"
 -pattern:"*.parquet" -format:parquet -limit:2 -cr:10.0 -dontWait:true

  • For a blob URI that refers to hierarchical folder structure, like https://storageaccount/mycontainer/myfolder/2002/12/01/blobname.extension,

    The value for -creationTimePattern argument is part of the folder structure: "'folder/'yyyy/MM/dd'/blob'"

      LightIngest.exe "https://ingest-{Cluster name and region}.kusto.windows.net;Fed=True" -db:{Database} -table:Trips -source:"https://{Account}.blob.core.windows.net/{ROOT_CONTAINER};{StorageAccountKey}" -creationTimePattern:"'mycontainer/myfolder/'yyyy/MM/dd'/'"
   -pattern:"*.csv.gz" -format:csv -limit:2 -ignoreFirst:true -cr:10.0 -dontWait:true

Ingesting blobs using a storage account key or a SAS token

  • Ingest 10 blobs under specified storage account ACCOUNT, in folder DIR, under container CONT, and matching the pattern *.csv.gz
  • Destination is database DB, table TABLE, and the ingestion mapping MAPPING is precreated on the destination
  • The tool will wait until the ingest operations complete
  • Note the different options for specifying the target database and storage account key vs. SAS token
LightIngest.exe "https://ingest-{ClusterAndRegion}.kusto.windows.net;Fed=True"
  -database:DB
  -table:TABLE
  -source:"https://ACCOUNT.blob.core.windows.net/{ROOT_CONTAINER};{StorageAccountKey}"
  -prefix:"DIR"
  -pattern:*.csv.gz
  -format:csv
  -mappingRef:MAPPING
  -limit:10

LightIngest.exe "https://ingest-{ClusterAndRegion}.kusto.windows.net;Fed=True;Initial Catalog=DB"
  -table:TABLE
  -source:"https://ACCOUNT.blob.core.windows.net/{ROOT_CONTAINER}?{SAS token}"
  -prefix:"DIR"
  -pattern:*.csv.gz
  -format:csv
  -mappingRef:MAPPING
  -limit:10

Ingesting all blobs in a container, not including header rows

  • Ingest all blobs under specified storage account ACCOUNT, in folder DIR1/DIR2, under container CONT, and matching the pattern *.csv.gz
  • Destination is database DB, table TABLE, and the ingestion mapping MAPPING is precreated on the destination
  • Source blobs contain header line, so the tool is instructed to drop the first record of each blob
  • The tool will post the data for ingestion and won't wait for the ingest operations to complete
LightIngest.exe "https://ingest-{ClusterAndRegion}.kusto.windows.net;Fed=True"
  -database:DB
  -table:TABLE
  -source:"https://ACCOUNT.blob.core.windows.net/{ROOT_CONTAINER}?{SAS token}"
  -prefix:"DIR1/DIR2"
  -pattern:*.csv.gz
  -format:csv
  -mappingRef:MAPPING
  -ignoreFirstRow:true

Ingesting all JSON files from a path

  • Ingest all files under path PATH, matching the pattern *.json
  • Destination is database DB, table TABLE, and the ingestion mapping is defined in local file MAPPING_FILE_PATH
  • The tool will post the data for ingestion and won't wait for the ingest operations to complete
LightIngest.exe "https://ingest-{ClusterAndRegion}.kusto.windows.net;Fed=True"
  -database:DB
  -table:TABLE
  -source:"PATH"
  -pattern:*.json
  -format:json
  -mappingPath:"MAPPING_FILE_PATH"

Ingesting files and writing diagnostic trace files

  • Ingest all files under path PATH, matching the pattern *.json
  • Destination is database DB, table TABLE, and the ingestion mapping is defined in local file MAPPING_FILE_PATH
  • The tool will post the data for ingestion and won't wait for the ingest operations to complete
  • Diagnostics trace files will be written locally under folder LOGS_PATH
LightIngest.exe "https://ingest-{ClusterAndRegion}.kusto.windows.net;Fed=True"
  -database:DB
  -table:TABLE
  -source:"PATH"
  -pattern:*.json
  -format:json
  -mappingPath:"MAPPING_FILE_PATH"
  -trace:"LOGS_PATH"