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Use LightIngest to ingest data into Azure Data Explorer

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, an Azure blob storage container, or an Amazon S3 bucket.

LightIngest is most useful when you want to ingest a large amount of data, because there's 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.

For an example of how to autogenerate a LightIngest command, see ingest historical data.

Note

Ingestion supports a maximum file size of 6 GB. The recommendation is to ingest files between 100 MB and 1 GB.

Prerequisites

Run LightIngest

To run LightIngest:

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

    Tip

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

  2. 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 "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

Performance recommendations

  • To best manage the ingestion load and recover from transient errors, use the ingestion endpoint at https://ingest-{yourClusterNameAndRegion}.kusto.windows.net.

  • 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 Type Description Required
string A Kusto connection string specifying the Kusto endpoint that handles the ingestion. This value should be enclosed with double quotes. ✔️
-database, -db string The target Azure Data Explorer database name.
-table string The target Azure Data Explorer table name. ✔️
-sourcePath, -source string The location of the source data, which can be either a local file path, the root URI of an Azure blob container, or the URI of an Amazon S3 bucket. If the data is stored in Azure blobs, the URI must include the storage account key or Shared Access Signature (SAS). If the data is in an S3 bucket, the URI must include the credential key. We recommend enclosing this value in double quotes. For more information, see Storage connection strings. Pass -sourcePath:;impersonate to list Azure storage items with user permissions (user prompt authorization). ✔️
-managedIdentity, -mi string Client ID of the managed identity (user-assigned or system-assigned) to use for connecting. Use "system" for system-assigned identity.
-azCli bool If set, uses the Azure CLI to authenticate to the Kusto service. The Azure CLI must be installed and logged in.
-ingestWithManagedIdentity, -ingestmi string Client ID of the managed identity (user-assigned or system-assigned) installed on the Kusto service to download from storage. Use "system" for system-assigned identity.
-connectToStorageWithManagedIdentity, -storageMi string Client ID of the managed identity (user-assigned or system-assigned) installed on the client side to list from storage.
-connectToStorageWithUserAuth, -storageUserAuth string Authenticate to the data source storage service with user credentials. The options for this value are PROMPT or DEVICE_CODE.
-connectToStorageLoginUri, -storageLoginUri string If -connectToStorageWithUserAuth is set, you can optionally provide a Microsoft Entra ID login URI.
-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. We recommend enclosing this value in double quotes.
-pattern string Pattern by which source files/blobs are picked. Supports wildcards. For example, "*.csv". We recommend enclosing this value in double quotes.
-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". We recommend enclosing this value in double quotes.
-format, -f string Source data format. Must be one of the supported formats
-ingestionMappingPath, -mappingPath string A path to a local file for ingestion column mapping. See data mappings.
-ingestionMappingRef, -mappingRef string The name of an ingestion column mapping that was previously created on the table. See data mappings.
-creationTimePattern string When set, is used to extract the CreationTime property from the file or blob path. See How to ingest data using CreationTime.
-ignoreFirstRow, -ignoreFirst bool If set, the first record of each file/blob is ignored. For example, if the source data has headers.
-tag string Tags to associate with the ingested data. Multiple occurrences are permitted
-dontWait bool If set to true, doesn't wait for ingestion completion. Useful when ingesting large amounts of files/blobs.
-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.
-limit, -l integer If set, limits the ingestion to first N files.
-listOnly, -list bool If set, only displays the items that would have been selected for ingestion.
-ingestTimeout integer Timeout in minutes for all ingest operations completion. Defaults to 60.
-forceSync bool If set, forces synchronous ingestion. Defaults to false.
-interactive bool If set to false, doesn't prompt for arguments confirmation. For unattended flows and non-interactive environments. Default is true.
-dataBatchSize integer Sets the total size limit (MB, uncompressed) of each ingest operation.
-filesInBatch integer Sets the file/blob count limit of each ingest operation.
-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).

Azure blob-specific capabilities

When used with Azure blobs, LightIngest uses 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

The following examples assume you've installed LightIngest binaries for your operating system. If you've installed LightIngest as a .NET tool, substitute LightIngest with LightIngest in the examples.

Ingest historical data with the CreationTime property

When you load historical data from existing system to Azure Data Explorer, all records receive the same 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 "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 "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 waits until the ingest operations complete
  • Note the different options for specifying the target database and storage account key vs. SAS token
LightIngest "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 "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 posts the data for ingestion and doesn't wait for the ingest operations to complete
LightIngest "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 posts the data for ingestion and doesn't wait for the ingest operations to complete
LightIngest "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 posts the data for ingestion and doesn't wait for the ingest operations to complete
  • Diagnostics trace files are written locally under folder LOGS_PATH
LightIngest "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"

Authenticate with managed identity

There are three actions LightIngest performs that can use managed identity for authentication. The use of managed identity in each step does not require use of managed identity in other steps. For each action, the related command-line argument is given.

  • Connect to Kusto cluster: To queue the ingestion, the tool uses a connection string. Use the "-mi" argument to specify a managed identity installed on the client VM that has ingest privileges in the target database.

  • Connect to Azure Storage to download blobs: Use "-ingestmi" to specify a managed identity installed on the Kusto service that has read privileges on the storage container.

  • Connect to Azure Storage to list container blobs: Use the "-storageMi" argument to specify a managed identity installed on the client VM that has list privileges on the storage container. If you're using this method but not the previous one (connect to Azure storage to download blobs), the managed identity must have read privileges as well and a token will be passed to the Kusto service to be used for the ingestion. It is therefore recommended to set all the three arguments.