Enhance SCRIPT to support operations on STDOUT

[marcellorinaldo]

As now, the SCRIPT command is able to produce an output on file or in form of a ResultSet if no TO clause is specified.

Since the database can be large and disk space or heap memory can be limited, it would be useful to have the SCRIPT command output to stdout and RUNSCRIPT read from stdin so to avoid intermediate temporary files.

To achieve the result we tried using UNIX named pipes without success: the pipe is always replaced by a regular file. Note that the RunScript tool seems to be able to read from a named pipe.

[katzyn]

SCRIPT and RUNSCRIPT commands are executed on the server side, server process normally doesn't have I/O streams. Hypothetically they can support them only in embedded databases, but from my point of view it's a bad idea to introduce a feature with this limitation.

Actually there are special files /dev/stdin, /dev/stdout, /dev/stderr on POSIX systems and con on Windows and there is no need to duplicate their functionality. The only problem is that SCRIPT tries to delete the target file, it needs a flag to append output to existing file instead.

[marcellorinaldo]

SCRIPT and RUNSCRIPT commands are executed on the server side, server process normally doesn't have I/O streams. Hypothetically they can support them only in embedded databases, but from my point of view it's a bad idea to introduce a feature with this limitation.

I agree that on servers this functionality has no sense. However, on embedded environments where memory and disk space are scarce resources it would be nice to combine SCRIPT and RUNSCRIPT in pipe operations to avoid the creation of intermediate files. In this way it is possible to migrate a persisted database to the new version just using the command line tool without temporary files.

Actually there are special files /dev/stdin, /dev/stdout, /dev/stderr on POSIX systems and con on Windows and there is no need to duplicate their functionality. The only problem is that SCRIPT tries to delete the target file, it needs a flag to append output to existing file instead.

So, is it feasible to implement this special flag? Then, is it safe to import a database from a pipe using RUNSCRIPT?

[grandinj]

There are already command line tools for doing RUNSCRIPT and SCRIPT

https://h2database.com/html/tutorial.html#command_line_tools

but they might need enhancement to work with pipes