Where is the real documentation on directory access servers?

[VolkerBarth]

There have been some questions on that lately in this forum, and I'm also stuck with some limitations, and the 12.0.1 help is rather quiet on this facility...

And I guess I think I remember I have once seen several samples in the newsgroups, possibly in an answer by Mark. Unfortunately, even Google couldn't help to find them (if they have been published i>anywhere).

IMHO, what is really missing in the docs are topics like:

• Samples to INSERT, UPDATE, DELETE from proxy tables on DASs
• Can I use an environment variable within the CREATE SERVER definition, such as %TEMP%? - In my tests, no.
• Can I use anything else as a "file_name = " condition to INSERT/UPDATE/DELETE files? - In my tests, no - even "file_name like" seems to fail
  And if not, how to use cursor loops to use other conditions?
• Can I use INSERT ... SELECT to copy files between two DASs? - Seems to work
• Can I use all fields to insert/update the proxy tables, or are some fields "computed"? - Apparently, specifying unfitting values for contents and size might lead to problems...
• How to debug such access? - Setting CIS_OPTION = 7 is not too helpful here, methinks, in contrast to other server types.
• Should I copy the contents via querying/inserting the contents field, or is using xp_read_file/xp_write_file the preferred method?

In my tests (with 12.0.1.3726 on Windows XP), directory access servers seem rather different to handle in contrast to other remote access servers, and that should be documented better.

If there's a whitepaper or the like, I'd like to get to know:)

[VolkerBarth]

A further issue: What is a table scan w.r.t. DASs as documented here:

To improve performance, avoid selecting the contents column when using queries that result in a table scan.

BTW: That page at least explains why to use file_name equality conditions from a performance point of view - but it doesn't tell whether other conditions will fail (for DML statements)...

[thomas_duemesnil]

Did you post a Enhancement Request on http://dcx.sybase.com ? I think that is the way to go here.

[VolkerBarth]

Good suggestion - but I'm gonna wait for hints to other official material first...

[VolkerBarth]

A partial success - with the help of Breck's great "SQL Anywhere Technical Documents" list, I found the following technical document that at least shows some usages, including creating a directory:

• How to Use the Directory Access Server Feature in SQL Anywhere 10

I had used the Google search facility on Breck's page with "directory", but that didn't return a fitting result. However, Just searching within the page itself showed the entry - sigh...

Still I think there are much more topics and details waiting to be explained.

[Breck_Carter]

Alas, the Google Custom Search Engine is getting worse over time, not better, and I have run out of ideas to make it better... the good news is, having all the titles on one page does make the browser "search on this page" facility fairly useful.