On Sunday 12 October 2008 12:16, Helen Borrie wrote:

> 3. Now, you might argue that all it takes is to put the data file tree
> beneath the Firebird root, e.g. in ../datafiles (similar to UDFAccess) and
> set up ExternalFileAccess RESTRICT to the relative tree address. Then you
> could just plonk all your external files there and define external tables
> to point to this platform-independent location. Doesn't work. For
> example, pathing the <filespec> argument as
> 'datafiles\specialdir\special.data' results (on Windows) in a violation of
> your RESTRICT list as Firebird attempts to open a file in
> c:\windows\system32\datafiles\specialdir.

Helen, you are not completely precise here. Yep, it does not work for a file
with pathname. But it works just fine for a simple file name. For example,
with line in firebird.conf:

ExternalFileAccess = Restrict /opt/extern

I specify default location of external files. And can use it. After:

SQL> create table qq external file 'zz' (x int);
SQL> insert into qq values(1);
SQL> commit;

I have file /opt/extern/zz. If I rename '/opt/extern' to be '/opt/external'
and change appropriately line in firebird.conf, I can access it successfully.
Moreover, with line of firebird.conf:

ExternalFileAccess = Restrict /var/log;/opt/external

and external file 'zz' in /opt/external, it's still accessible. I.e. the file
is searched for in all Restrict entries.

Certainly I agree that it will be good to support relative paths too. Can you
add a tracker item for it?

> So - is it possible to do some or all of the following:
>
> 1. Add a new config parameter for ExternalFileRoot to take care of the
> platform dependence problem. There can be no default, obviously, so
> enforce ExternalFileAccess=NONE, regardless of current settings, if
> ExternalFileRoot is empty or invalid.

Currently any item of restrict list works as external file root. In case when
file with desired name is missing in any of them, new one will be created in
the first dir. That behavior was discussed in devel a few years ago.

> 2. Allow (encourage? enforce?) a UDFAccess-style relative path for the
> <filespec> argument of CREATE TABLE...EXTERNAL FILE

I do not understand big difference between this and p.1 - same theng said in
other manner...

> 3. Make Firebird interpret slash and backslash in the subdirectory parts
> of the strings appropriately for the platform it's running on.

If it does not work in any place of engine - this is a bug, not worth even
discussing in architect. Just add an item to the tracker:)

> 4. And - of course - wake up and fix the code for handling delimited text
> record formats and get REAL LOVE by enabling an external table to suck in
> the contents of text or binary files (as XML processors can do) for
> treatment as clobs and blobs.

This is what is really worth discussing here. And it's really much to discuss
before doing something.

First problem. Currently external engines access is actively developed by the
project. Looks like very soon we will be able access virtually any file
format using ODBC. Would not extending of external tables be just a
duplication of our efforts in that direction?

Alex.