Please be aware that the SAP SQL Anywhere Forum will be shut down on August 29th, 2024 when all it's content will be migrated to the SAP Community.

For Version and all subsequent versions, unless a "behavior change" is documented, is it safe to assume that CONNECTION_PROPERTY ( 'Name' ) evaluated inside an event will always return the event name as defined by the CREATE EVENT statement?

I want to write the following...

   if another invocation of this event is already running
   then quit this invocation of the event;

and I plan to query sa_conn_info() to do that.

asked 14 Oct '10, 17:20

Breck%20Carter's gravatar image

Breck Carter
accept rate: 20%

edited 06 Aug '11, 17:27

good question! I've got a handful of things that could really benefit from this.

(14 Oct '10, 23:16) Ron Hiner

Not really an answer, but I use following on V10:

ALTER FUNCTION "DBA"."EventIsRunning"() RETURNS INTEGER DETERMINISTIC BEGIN DECLARE @active_events integer ; -- SELECT event_parameter('NumActive') INTO @active_events ; -- if @active_events > 1 then Return 1 -- another instance of this event is already running end if ; -- RETURN 0 -- this is the only running instance of this event END

(15 Oct '10, 11:03) Dmitri
Comment Text Removed

@Dmitri: I guess that's one of the best of those "not really answers" around here:)

(15 Oct '10, 14:41) Volker Barth

@Dmtri: Shouldn't that function be NOT DETERMINSTIC? - IMHO, separate runs may give different results though the (empty) parameter list remains unchanged.

(18 Oct '10, 07:18) Volker Barth

Well, maybe... but TBH I don't expect it to be called multilple times within single query.

(19 Oct '10, 11:11) Dmitri

The value of connection_property('Name',number) for an event will be the name of the event; however, there is nothing preventing a normal connection from using the same name. The value of connection_property('EventName',number) is also the name of the event, but will be NULL for non-event connections. If this is the only property you are going to be using, sa_conn_list() is a more efficient way to get a list of connections. sa_conn_list was added in version 10. To limit the number of instances of an event that are active, checking the value of event_parameter('NumActive') within the event is the simplest approach.

permanent link

answered 15 Oct '10, 13:25

Bruce%20Hay's gravatar image

Bruce Hay
accept rate: 48%

Question: So when did NumActive get added to SQL Anywhere? Answer: It's been there since Day One, when CREATE EVENT was added in Version 7. Yikes! Maybe it's time for me to take a course on SQL Anywhere, maybe get Dmitri to teach it.

(15 Oct '10, 13:57) Breck Carter

I would sign up for that.

(15 Oct '10, 14:17) Siger Matt

@Breck: To make it even more "embarassing", there' s even a sample with NumActive in the docs, cf. - Double-Yikes!!

(15 Oct '10, 14:39) Volker Barth

It gets worse... not only have I not taken a course, or read the Help since Version 6, but apparently I don't even read this website:

(16 Oct '10, 09:54) Breck Carter

@Volker: At this point I may not be the right person to suggest the Help get changed, but the statement IF EVENT_PARAMETER( 'NumActive' ) = 1 THEN creeps me out because it is relying on an implicit data conversion... EVENT_PARAMETER returns VARCHAR. Such implicit conversions are not as well documented in SQL Anywhere as they are in, say PL/I (the Father Of All Implicit Type Conversions)... and even with PL/I wizened pros learned to be explicit about all such conversions.

(16 Oct '10, 10:01) Breck Carter

Correction: When I said I have "not read the Help since Version 6" I mean cover-to-cover, end-to-end, in one swell foop, er, fell swoop. I read the Help every day, but just individual topics.

(16 Oct '10, 10:08) Breck Carter

@Breck: I would not expect anyone (well, except the doc team) to have read the help completely for current versions... I remember to have read the v5.5 docs (nearly) from page to page, but nowadays - that's way too much stuff, I guess. - Another question to come: "What is the most important SQL Anywhere feature you wish you had noticed when it was introduced and not n years later?"

(16 Oct '10, 17:46) Volker Barth
More comments hidden
showing 5 of 7 show all flat view
Your answer
toggle preview

Follow this question

By Email:

Once you sign in you will be able to subscribe for any updates here



Answers and Comments

Markdown Basics

  • *italic* or _italic_
  • **bold** or __bold__
  • link:[text]( "title")
  • image?![alt text](/path/img.jpg "title")
  • numbered list: 1. Foo 2. Bar
  • to add a line break simply add two spaces to where you would like the new line to be.
  • basic HTML tags are also supported

Question tags:


question asked: 14 Oct '10, 17:20

question was seen: 2,583 times

last updated: 06 Aug '11, 17:27