Adding metadata to C++ libraries

For example, the following code demonstrates adding metadata to the Add2Ints example (see C++ Example: Add2Ints).

You can add metadata, such as author name, the version of the library, a description of your library, and so on to your library. This metadata lets you track the version of your function that is deployed on a Vertica Analytic Database cluster and lets third-party users of your function know who created the function. Your library's metadata appears in the USER_LIBRARIES system table after your library has been loaded into the Vertica Analytic Database catalog.

You declare the metadata for your library by calling the RegisterLibrary() function in one of the source files for your UDx. If there is more than one function call in the source files for your UDx, whichever gets interpreted last as Vertica Analytic Database loads the library is used to determine the library's metadata.

The RegisterLibrary() function takes eight string parameters:

  • author contains whatever name you want associated with the creation of the library (your own name or your company's name for example).

  • library_build_tag is a string you want to use to represent the specific build of the library (for example, the SVN revision number or a timestamp of when the library was compiled). This is useful for tracking instances of your library as you are developing them.

  • library_version is the version of your library. You can use whatever numbering or naming scheme you want.

  • library_sdk_version is the version of the Vertica Analytic Database SDK Library for which you've compiled the library.

  • source_url is a URL where users of your function can find more information about it. This can be your company's website, the GitHub page hosting your library's source code, or whatever site you like.

  • description is a concise description of your library.

  • licenses_required is a placeholder for licensing information. You must pass an empty string for this value.

  • signature is a placeholder for a signature that will authenticate your library. You must pass an empty string for this value.

For example, the following code demonstrates adding metadata to the Add2Ints example (see C++ example: Add2Ints).

// Register the factory with Vertica

// Register the library's metadata.
RegisterLibrary("Whizzo Analytics Ltd.",
                "Add 2 Integer Library",

Loading the library and querying the USER_LIBRARIES system table shows the metadata supplied in the call to RegisterLibrary():

=> CREATE LIBRARY add2intslib AS '/home/dbadmin/';
=> \x
Expanded display is on.
=> SELECT * FROM USER_LIBRARIES WHERE lib_name = 'add2intslib';
-[ RECORD 1 ]-----+----------------------------------------
schema_name       | public
lib_name          | add2intslib
lib_oid           | 45035996273869808
author            | Whizzo Analytics Ltd.
owner_id          | 45035996273704962
lib_file_name     |
md5_sum           | 732c9e145d447c8ac6e7304313d3b8a0
sdk_version       | v7.0.0-20131105
revision          | 125200
lib_build_tag     | 1234
lib_version       | 2.0
lib_sdk_version   | 7.0.0
source_url        |
description       | Add 2 Integer Library
licenses_required |
signature         |