A number of environment variables can be used to configure the behavior of the library. There are also functions to configure this behavior in code. The environment variables are convenient when troubleshooting problems.
Endpoint Overrides
GOOGLE_CLOUD_CPP_DATA_FUSION_ENDPOINT=...overrides theEndpointOption(which defaults to "datafusion.googleapis.com") used byMakeDataFusionConnection().
GOOGLE_CLOUD_CPP_ENABLE_TRACING=rpc: turns on tracing for most gRPC calls. The library injects an additional Stub decorator that prints each gRPC request and response. Unless you have configured your own logging backend, you should also setGOOGLE_CLOUD_CPP_ENABLE_CLOGto produce any output on the program's console.
See Also
google::cloud::LoggingComponentsOptionGOOGLE_CLOUD_CPP_TRACING_OPTIONS=...: modifies the behavior of gRPC tracing, including whether messages will be output on multiple lines, or whether string/bytes fields will be truncated.
See Also
google::cloud::GrpcTracingOptionsOptionGOOGLE_CLOUD_CPP_ENABLE_CLOG=yes: turns on logging in the library, basically the library always "logs" but the logging infrastructure has no backend to actually print anything until the application sets a backend or they set this environment variable.
[[["Easy to understand","easyToUnderstand","thumb-up"],["Solved my problem","solvedMyProblem","thumb-up"],["Other","otherUp","thumb-up"]],[["Hard to understand","hardToUnderstand","thumb-down"],["Incorrect information or sample code","incorrectInformationOrSampleCode","thumb-down"],["Missing the information/samples I need","missingTheInformationSamplesINeed","thumb-down"],["Other","otherDown","thumb-down"]],["Last updated 2025-09-04 UTC."],[[["\u003cp\u003eThis page provides documentation for various versions of the Data Fusion library, ranging from version 2.13.0 up to the latest release candidate, 2.37.0-rc.\u003c/p\u003e\n"],["\u003cp\u003eThe documentation highlights the use of environment variables for configuring the library's behavior, specifically for troubleshooting and adjusting settings.\u003c/p\u003e\n"],["\u003cp\u003eThe \u003ccode\u003eGOOGLE_CLOUD_CPP_DATA_FUSION_ENDPOINT\u003c/code\u003e environment variable allows users to override the default endpoint used by the \u003ccode\u003eMakeDataFusionConnection()\u003c/code\u003e function.\u003c/p\u003e\n"],["\u003cp\u003eTracing for gRPC calls can be enabled via \u003ccode\u003eGOOGLE_CLOUD_CPP_ENABLE_TRACING=rpc\u003c/code\u003e, with additional options provided by \u003ccode\u003eGOOGLE_CLOUD_CPP_TRACING_OPTIONS\u003c/code\u003e for modifying tracing behavior.\u003c/p\u003e\n"],["\u003cp\u003eLogging within the library can be enabled by setting \u003ccode\u003eGOOGLE_CLOUD_CPP_ENABLE_CLOG=yes\u003c/code\u003e, which activates the output of log messages to the console, however the environment variable \u003ccode\u003eGOOGLE_CLOUD_PROJECT\u003c/code\u003e is only used for examples and test cases.\u003c/p\u003e\n"]]],[],null,["Version 2.32.0keyboard_arrow_down\n\n- [2.42.0-rc (latest)](/cpp/docs/reference/datafusion/latest/datafusion-env)\n- [2.41.0](/cpp/docs/reference/datafusion/2.41.0/datafusion-env)\n- [2.40.0](/cpp/docs/reference/datafusion/2.40.0/datafusion-env)\n- [2.39.0](/cpp/docs/reference/datafusion/2.39.0/datafusion-env)\n- [2.38.0](/cpp/docs/reference/datafusion/2.38.0/datafusion-env)\n- [2.37.0](/cpp/docs/reference/datafusion/2.37.0/datafusion-env)\n- [2.36.0](/cpp/docs/reference/datafusion/2.36.0/datafusion-env)\n- [2.35.0](/cpp/docs/reference/datafusion/2.35.0/datafusion-env)\n- [2.34.0](/cpp/docs/reference/datafusion/2.34.0/datafusion-env)\n- [2.33.0](/cpp/docs/reference/datafusion/2.33.0/datafusion-env)\n- [2.32.0](/cpp/docs/reference/datafusion/2.32.0/datafusion-env)\n- [2.31.0](/cpp/docs/reference/datafusion/2.31.0/datafusion-env)\n- [2.30.0](/cpp/docs/reference/datafusion/2.30.0/datafusion-env)\n- [2.29.0](/cpp/docs/reference/datafusion/2.29.0/datafusion-env)\n- [2.28.0](/cpp/docs/reference/datafusion/2.28.0/datafusion-env)\n- [2.27.0](/cpp/docs/reference/datafusion/2.27.0/datafusion-env)\n- [2.26.0](/cpp/docs/reference/datafusion/2.26.0/datafusion-env)\n- [2.25.1](/cpp/docs/reference/datafusion/2.25.1/datafusion-env)\n- [2.24.0](/cpp/docs/reference/datafusion/2.24.0/datafusion-env)\n- [2.23.0](/cpp/docs/reference/datafusion/2.23.0/datafusion-env)\n- [2.22.1](/cpp/docs/reference/datafusion/2.22.1/datafusion-env)\n- [2.21.0](/cpp/docs/reference/datafusion/2.21.0/datafusion-env)\n- [2.20.0](/cpp/docs/reference/datafusion/2.20.0/datafusion-env)\n- [2.19.0](/cpp/docs/reference/datafusion/2.19.0/datafusion-env)\n- [2.18.0](/cpp/docs/reference/datafusion/2.18.0/datafusion-env)\n- [2.17.0](/cpp/docs/reference/datafusion/2.17.0/datafusion-env)\n- [2.16.0](/cpp/docs/reference/datafusion/2.16.0/datafusion-env)\n- [2.15.1](/cpp/docs/reference/datafusion/2.15.1/datafusion-env)\n- [2.14.0](/cpp/docs/reference/datafusion/2.14.0/datafusion-env)\n- [2.13.0](/cpp/docs/reference/datafusion/2.13.0/datafusion-env) \n\nEnvironment Variables\n=====================\n\nA number of environment variables can be used to configure the behavior of the library. There are also functions to configure this behavior in code. The environment variables are convenient when troubleshooting problems.\n\nEndpoint Overrides\n------------------\n\n- `GOOGLE_CLOUD_CPP_DATA_FUSION_ENDPOINT=...` overrides the `EndpointOption` (which defaults to \"datafusion.googleapis.com\") used by `MakeDataFusionConnection()`.\n\n###### See Also\n\n[`google::cloud::EndpointOption`](https://cloud.google.com/cpp/docs/reference/common/latest/structgoogle_1_1cloud_1_1EndpointOption.html)\n\nLogging\n-------\n\n`GOOGLE_CLOUD_CPP_ENABLE_TRACING=rpc`: turns on tracing for most gRPC calls. The library injects an additional Stub decorator that prints each gRPC request and response. Unless you have configured your own logging backend, you should also set `GOOGLE_CLOUD_CPP_ENABLE_CLOG` to produce any output on the program's console.\n\n###### See Also\n\n[`google::cloud::LoggingComponentsOption`](https://cloud.google.com/cpp/docs/reference/common/latest/structgoogle_1_1cloud_1_1LoggingComponentsOption.html)`GOOGLE_CLOUD_CPP_TRACING_OPTIONS=...`: modifies the behavior of gRPC tracing, including whether messages will be output on multiple lines, or whether string/bytes fields will be truncated.\n\n###### See Also\n\n[`google::cloud::GrpcTracingOptionsOption`](https://cloud.google.com/cpp/docs/reference/common/latest/structgoogle_1_1cloud_1_1GrpcTracingOptionsOption.html)`GOOGLE_CLOUD_CPP_ENABLE_CLOG=yes`: turns on logging in the library, basically the library always \"logs\" but the logging infrastructure has no backend to actually print anything until the application sets a backend or they set this environment variable.\n\n###### See Also\n\n[`google::cloud::LogBackend`](https://cloud.google.com/cpp/docs/reference/common/latest/classgoogle_1_1cloud_1_1LogBackend.html)\n\n###### See Also\n\n[`google::cloud::LogSink`](https://cloud.google.com/cpp/docs/reference/common/latest/classgoogle_1_1cloud_1_1LogSink.html)\n\nSetting the Default Project\n---------------------------\n\n`GOOGLE_CLOUD_PROJECT=...`: is used in examples and integration tests to configure the GCP project. This has no effect in the library."]]
