UDFs: Functions with Handler Code That Reads Files from a Stage Execute in the Owner’s Context¶

UDFs whose handler code reads files from a stage will execute in the owner’s context. A caller must pass the file location as a scoped URL, whether the handler code is in a UDF or procedure and regardless of whether they are running with caller’s or owner’s rights:

Previously:

When Java code in a UDF handler reads a file from a stage, it does so using the caller’s context.

A caller may pass the file’s location to the function using a form such as select my_function('@stage-name/filename.txt').

Handler code receives the stage URL and reads the file with SnowflakeFile.newInstance and SnowflakeFile.getInputStream or receives the file as a java.io.InputStream:

SnowflakeFile sfFile = SnowflakeFile.newInstance(file_url);
InputStream is = sfFile.getInputStream();

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Files read by handler code may be on an external stage or on a user or named internal stage.

Currently:

When Java code in a UDF handler reads a file from a stage, it will do so using the owner’s context.

For both UDFs and procedures, a caller must pass the file’s location in a scoped URL by using the BUILD_SCOPED_FILE_URL function, as in the following function example:

select my_func(build_scoped_file_url(@my_stage, 'filename.txt'));

Handler code receives the scoped URL and reads the file as before.

SnowflakeFile sfFile = SnowflakeFile.newInstance(scopedFileUrl);
InputStream is = sfFile.getInputStream();

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For files whose locations are specified within handler code (not as scoped URLs passed in by a caller), you can read the staged file in one of two ways: handler code can call the newInstance method with a boolean value for a new requireScopedUrl parameter; or handler code must use a scoped URL when creating an InputStream from the file path.

The following example uses SnowflakeFile.newInstance:

String filename = "@my_stage/filename.txt";
SnowflakeFile sfFile = SnowflakeFile.newInstance(filename, require_scoped_url = false);

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In addition, user stages are no longer supported as locations for files read by a handler. Files read by handler code must be on an external stage or on a named internal stage.

Ref: 1008