I'm sharpening up my Azure Data Factory chops, comparing Copy Activity performance vs Mapping Data Flows writing to a single CSV file in Azure Blob Storage.
When I write to a Single CSV through an Azure Blob Storage Linked Service (azureBlobLinkedService) through a Dataset (azureBlobSingleCSVFileNameDataset), using a Copy Activity get the output in the blob storage container that I expect. For example, an output file of MyData.csv in the container MyContainer under the folder /output/csv/singleFiles.
When I write to a Single CSV through the same Blob Storage Linked Service, but through a different DataSet (azureBlobSingleCSVNoFileNameDataset), using a Mapping Data Flow I get the following:
- MyContainer/output/csv/singleFiles (zero length file)
- MyContainer/output/csv/singleFiles/MyData.csv (contains the data that I expect)
I don't understand why I'm getting the zero length files produced when using a Mapping Data Flow.
Here are my source files:
linkedService/azureBlobLinkedService
{
"name": "azureBlobLinkedService",
"type": "Microsoft.DataFactory/factories/linkedservices",
"properties": {
"type": "AzureBlobStorage",
"parameters": {
"azureBlobConnectionStringSecretName": {
"type": "string"
}
},
"annotations": [],
"typeProperties": {
"connectionString": {
"type": "AzureKeyVaultSecret",
"store": {
"referenceName": "AzureKeyVaultLinkedService",
"type": "LinkedServiceReference"
},
"secretName": "@{linkedService().azureBlobConnectionStringSecretName}"
}
}
}
}
dataset/azureBlobSingleCSVFileNameDataset
{
"name": "azureBlobSingleCSVFileNameDataset",
"properties": {
"linkedServiceName": {
"referenceName": "azureBlobLinkedService",
"type": "LinkedServiceReference",
"parameters": {
"azureBlobConnectionStringSecretName": {
"value": "@dataset().azureBlobConnectionStringSecretName",
"type": "Expression"
}
}
},
"parameters": {
"azureBlobConnectionStringSecretName": {
"type": "string"
},
"azureBlobSingleCSVFileName": {
"type": "string"
},
"azureBlobSingleCSVFolderPath": {
"type": "string"
},
"azureBlobSingleCSVContainerName": {
"type": "string"
}
},
"annotations": [],
"type": "DelimitedText",
"typeProperties": {
"location": {
"type": "AzureBlobStorageLocation",
"fileName": {
"value": "@dataset().azureBlobSingleCSVFileName",
"type": "Expression"
},
"folderPath": {
"value": "@dataset().azureBlobSingleCSVFolderPath",
"type": "Expression"
},
"container": {
"value": "@dataset().azureBlobSingleCSVContainerName",
"type": "Expression"
}
},
"columnDelimiter": ",",
"escapeChar": "\\",
"firstRowAsHeader": true,
"quoteChar": "\""
},
"schema": []
},
"type": "Microsoft.DataFactory/factories/datasets"
}
pipeline/Azure SQL Table to Blob Single CSV Copy Pipeline (this produces expected results)
{
"name": "Azure SQL Table to Blob Single CSV Copy Pipeline",
"properties": {
"activities": [
{
"name": "Copy Azure SQL Table to Blob Single CSV",
"type": "Copy",
"dependsOn": [],
"policy": {
"timeout": "7.00:00:00",
"retry": 0,
"retryIntervalInSeconds": 30,
"secureOutput": false,
"secureInput": false
},
"userProperties": [],
"typeProperties": {
"source": {
"type": "AzureSqlSource",
"queryTimeout": "02:00:00"
},
"sink": {
"type": "DelimitedTextSink",
"storeSettings": {
"type": "AzureBlobStorageWriteSettings"
},
"formatSettings": {
"type": "DelimitedTextWriteSettings",
"quoteAllText": true,
"fileExtension": ".csv"
}
},
"enableStaging": false
},
"inputs": [
{
"referenceName": "azureSqlDatabaseTableDataset",
"type": "DatasetReference",
"parameters": {
"azureSqlDatabaseConnectionStringSecretName": {
"value": "@pipeline().parameters.sourceAzureSqlDatabaseConnectionStringSecretName",
"type": "Expression"
},
"azureSqlDatabaseTableSchemaName": {
"value": "@pipeline().parameters.sourceAzureSqlDatabaseTableSchemaName",
"type": "Expression"
},
"azureSqlDatabaseTableTableName": {
"value": "@pipeline().parameters.sourceAzureSqlDatabaseTableTableName",
"type": "Expression"
}
}
}
],
"outputs": [
{
"referenceName": "azureBlobSingleCSVFileNameDataset",
"type": "DatasetReference",
"parameters": {
"azureBlobConnectionStringSecretName": {
"value": "@pipeline().parameters.sinkAzureBlobConnectionStringSecretName",
"type": "Expression"
},
"azureBlobSingleCSVFileName": {
"value": "@pipeline().parameters.sinkAzureBlobSingleCSVFileName",
"type": "Expression"
},
"azureBlobSingleCSVFolderPath": {
"value": "@pipeline().parameters.sinkAzureBlobSingleCSVFolderPath",
"type": "Expression"
},
"azureBlobSingleCSVContainerName": {
"value": "@pipeline().parameters.sinkAzureBlobSingleCSVContainerName",
"type": "Expression"
}
}
}
]
}
],
"parameters": {
"sourceAzureSqlDatabaseConnectionStringSecretName": {
"type": "string"
},
"sourceAzureSqlDatabaseTableSchemaName": {
"type": "string"
},
"sourceAzureSqlDatabaseTableTableName": {
"type": "string"
},
"sinkAzureBlobConnectionStringSecretName": {
"type": "string"
},
"sinkAzureBlobSingleCSVContainerName": {
"type": "string"
},
"sinkAzureBlobSingleCSVFolderPath": {
"type": "string"
},
"sinkAzureBlobSingleCSVFileName": {
"type": "string"
}
},
"annotations": []
},
"type": "Microsoft.DataFactory/factories/pipelines"
}
dataset/azureBlobSingleCSVNoFileNameDataset: (no filename in dataset required by mapping data flow, set in the mapping data flow)
{
"name": "azureBlobSingleCSVNoFileNameDataset",
"properties": {
"linkedServiceName": {
"referenceName": "azureBlobLinkedService",
"type": "LinkedServiceReference",
"parameters": {
"azureBlobConnectionStringSecretName": {
"value": "@dataset().azureBlobConnectionStringSecretName",
"type": "Expression"
}
}
},
"parameters": {
"azureBlobConnectionStringSecretName": {
"type": "string"
},
"azureBlobSingleCSVFolderPath": {
"type": "string"
},
"azureBlobSingleCSVContainerName": {
"type": "string"
}
},
"annotations": [],
"type": "DelimitedText",
"typeProperties": {
"location": {
"type": "AzureBlobStorageLocation",
"folderPath": {
"value": "@dataset().azureBlobSingleCSVFolderPath",
"type": "Expression"
},
"container": {
"value": "@dataset().azureBlobSingleCSVContainerName",
"type": "Expression"
}
},
"columnDelimiter": ",",
"escapeChar": "\\",
"firstRowAsHeader": true,
"quoteChar": "\""
},
"schema": []
},
"type": "Microsoft.DataFactory/factories/datasets"
}
dataflow/azureSqlDatabaseTableToAzureBlobSingleCSVDataFlow
{
"name": "azureSqlDatabaseTableToAzureBlobSingleCSVDataFlow",
"properties": {
"type": "MappingDataFlow",
"typeProperties": {
"sources": [
{
"dataset": {
"referenceName": "azureSqlDatabaseTableDataset",
"type": "DatasetReference"
},
"name": "readFromAzureSqlDatabase"
}
],
"sinks": [
{
"dataset": {
"referenceName": "azureBlobSingleCSVNoFileNameDataset",
"type": "DatasetReference"
},
"name": "writeToAzureBlobSingleCSV"
}
],
"transformations": [
{
"name": "enrichWithRuntimeMetadata"
}
],
"script": "\nparameters{\n\tsourceConnectionSecretName as string,\n\tsinkConnectionStringSecretName as string,\n\tsourceObjectName as string,\n\tsinkObjectName as string,\n\tdataFactoryName as string,\n\tdataFactoryPipelineName as string,\n\tdataFactoryPipelineRunId as string,\n\tsinkFileNameNoPath as string\n}\nsource(allowSchemaDrift: true,\n\tvalidateSchema: false,\n\tisolationLevel: 'READ_UNCOMMITTED',\n\tformat: 'table') ~> readFromAzureSqlDatabase\nreadFromAzureSqlDatabase derive({__sourceConnectionStringSecretName} = $sourceConnectionSecretName,\n\t\t{__sinkConnectionStringSecretName} = $sinkConnectionStringSecretName,\n\t\t{__sourceObjectName} = $sourceObjectName,\n\t\t{__sinkObjectName} = $sinkObjectName,\n\t\t{__dataFactoryName} = $dataFactoryName,\n\t\t{__dataFactoryPipelineName} = $dataFactoryPipelineName,\n\t\t{__dataFactoryPipelineRunId} = $dataFactoryPipelineRunId) ~> enrichWithRuntimeMetadata\nenrichWithRuntimeMetadata sink(allowSchemaDrift: true,\n\tvalidateSchema: false,\n\tpartitionFileNames:[($sinkFileNameNoPath)],\n\tpartitionBy('hash', 1),\n\tquoteAll: true) ~> writeToAzureBlobSingleCSV"
}
}
}
pipeline/Azure SQL Table to Blob Single CSV Data Flow Pipeline (this produces the expected results, plus zero-byte file at folder paths.)
{
"name": "Azure SQL Table to Blob Single CSV Data Flow Pipeline",
"properties": {
"activities": [
{
"name": "Copy Sql Database Table To Blob Single CSV Data Flow",
"type": "ExecuteDataFlow",
"dependsOn": [],
"policy": {
"timeout": "7.00:00:00",
"retry": 0,
"retryIntervalInSeconds": 30,
"secureOutput": false,
"secureInput": false
},
"userProperties": [],
"typeProperties": {
"dataflow": {
"referenceName": "azureSqlDatabaseTableToAzureBlobSingleCSVDataFlow",
"type": "DataFlowReference",
"parameters": {
"sourceConnectionSecretName": {
"value": "'@{pipeline().parameters.sourceAzureSqlDatabaseConnectionStringSecretName}'",
"type": "Expression"
},
"sinkConnectionStringSecretName": {
"value": "'@{pipeline().parameters.sinkAzureBlobConnectionStringSecretName}'",
"type": "Expression"
},
"sourceObjectName": {
"value": "'@{concat('[', pipeline().parameters.sourceAzureSqlDatabaseTableSchemaName, '].[', pipeline().parameters.sourceAzureSqlDatabaseTableTableName, ']')}'",
"type": "Expression"
},
"sinkObjectName": {
"value": "'@{concat(pipeline().parameters.sinkAzureBlobSingleCSVContainerName, '/', pipeline().parameters.sinkAzureBlobSingleCSVFolderPath, '/', \npipeline().parameters.sinkAzureBlobSingleCSVFileName)}'",
"type": "Expression"
},
"dataFactoryName": {
"value": "'@{pipeline().DataFactory}'",
"type": "Expression"
},
"dataFactoryPipelineName": {
"value": "'@{pipeline().Pipeline}'",
"type": "Expression"
},
"dataFactoryPipelineRunId": {
"value": "'@{pipeline().RunId}'",
"type": "Expression"
},
"sinkFileNameNoPath": {
"value": "'@{pipeline().parameters.sinkAzureBlobSingleCSVFileName}'",
"type": "Expression"
}
},
"datasetParameters": {
"readFromAzureSqlDatabase": {
"azureSqlDatabaseConnectionStringSecretName": {
"value": "@pipeline().parameters.sourceAzureSqlDatabaseConnectionStringSecretName",
"type": "Expression"
},
"azureSqlDatabaseTableSchemaName": {
"value": "@pipeline().parameters.sourceAzureSqlDatabaseTableSchemaName",
"type": "Expression"
},
"azureSqlDatabaseTableTableName": {
"value": "@pipeline().parameters.sourceAzureSqlDatabaseTableTableName",
"type": "Expression"
}
},
"writeToAzureBlobSingleCSV": {
"azureBlobConnectionStringSecretName": {
"value": "@pipeline().parameters.sinkAzureBlobConnectionStringSecretName",
"type": "Expression"
},
"azureBlobSingleCSVFolderPath": {
"value": "@pipeline().parameters.sinkAzureBlobSingleCSVFolderPath",
"type": "Expression"
},
"azureBlobSingleCSVContainerName": {
"value": "@pipeline().parameters.sinkAzureBlobSingleCSVContainerName",
"type": "Expression"
}
}
}
},
"compute": {
"coreCount": 8,
"computeType": "General"
}
}
}
],
"parameters": {
"sourceAzureSqlDatabaseConnectionStringSecretName": {
"type": "string"
},
"sourceAzureSqlDatabaseTableSchemaName": {
"type": "string"
},
"sourceAzureSqlDatabaseTableTableName": {
"type": "string"
},
"sinkAzureBlobConnectionStringSecretName": {
"type": "string"
},
"sinkAzureBlobSingleCSVContainerName": {
"type": "string"
},
"sinkAzureBlobSingleCSVFolderPath": {
"type": "string"
},
"sinkAzureBlobSingleCSVFileName": {
"type": "string"
}
},
"annotations": []
},
"type": "Microsoft.DataFactory/factories/pipelines"
}
