Updating metadata

Posted by / 08-Jan-2017 08:00

Be sure to read the section below on package naming conventions, tagging versions and the importance of a .

Packages can be in more complicated states, indicated by annotations to the right of the installed package version; we will explain these states and annotations as we encounter them.

There are options to change this behavior such that While SQLAlchemy directly supports emitting CREATE and DROP statements for schema constructs, the ability to alter those constructs, usually via the ALTER statement as well as other database-specific constructs, is outside of the scope of SQLAlchemy itself.

While it’s easy enough to emit ALTER statements and similar by hand, such as by passing a string to construct, it’s a common practice to automate the maintenance of database schemas in relation to application code using schema migration tools.

So rather than installing a package, you just add it to the list of requirements and then "resolve" what needs to be installed.

In particular, this means that if some package had been installed because it was needed by a previous version of something you wanted, and a newer version doesn't have that requirement anymore, updating will actually remove that package.

This means that you tell it what you want and it figures out what versions to install (or remove) to satisfy those requirements optimally – and minimally.

There are two major migration tools available for SQLAlchemy: provides a constant ‘anonymous label’ for this Column Element.

This is a label() expression which will be named at compile time.

The prefix may be used across a repository or vary based on collection within the repository.

It is not recommended to import CSV files of more than 1,000 lines (i.e. When importing files larger than this, it may be difficult for an Administrator to accurately verify the changes that the import tool states it will make.

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The same label() is returned each time anon_label is called so that expressions can reference anon_label multiple times, producing the same label name at compile time.

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