A custom ostream

A custom destination for ostream means implementing your own ostreambuf. If you want your streambuf to actually buffer (i.e. don’t connect to the database after each character), the easiest way to do that is by creating a class inheriting from std::stringbuf. The only function that you’ll need to override is the sync() method, which is being called whenever the stream is flushed.

class MyBuf : public std::stringbuf
    virtual int sync() {
        // add this->str() to database here
        // (optionally clear buffer afterwards)

You can then create a std::ostream using your buffer:

MyBuf buff;
std::ostream stream(&buf)

Most people advised against redirecting the stream to a database, but they ignored my description that the database basically has a single blob field where all text is going to.
In rare cases, I might send data to a different field. This can be facilitated with custom attributes understood by my stream. For example:

MyStream << "Some text " << process_id(1234) << "more text" << std::flush

The code above will create a record in the database with:

blob: 'Some text more text'
process_id: 1234

process_id() is a method returning a structure ProcessID. Then, in the implementation of my ostream, I have an operator<<(ProcessID const& pid), which stores the process ID until it gets written. Works great!

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