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 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:)

asked 12 Sep '12, 17:36

Volker%20Barth's gravatar image

Volker Barth
accept rate: 34%

edited 12 Sep '12, 17:41

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)...

(12 Sep '12, 17:57) Volker Barth

Did you post a Enhancement Request on ? I think that is the way to go here.

(13 Sep '12, 06:16) Thomas Dueme...
Replies hidden

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

(13 Sep '12, 06:51) Volker Barth

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:

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.

permanent link

answered 13 Sep '12, 04:01

Volker%20Barth's gravatar image

Volker Barth
accept rate: 34%


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.

(13 Sep '12, 11:18) Breck Carter
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question asked: 12 Sep '12, 17:36

question was seen: 2,931 times

last updated: 13 Sep '12, 11:18