dblink_exists

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ml
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dblink_exists

ml
Hello,

I need a function like "dblink_exists()", but there is no one.
Here is my script:

create function trading.stats_symbols()  returns boolean as  
$$
declare
sql text;
begin
sql='...';
truncate trading.stats_symbols ;
perform dblink_connect('updatesymbols', 'dbname=ftc') ;
perform dblink_send_query('updatesymbols', sql) ;
perform dblink_disconnect('updatesymbols') ;
end;
$$ language plpgsql;

My general problem:
I need a command that send a answer immediately and not, when the query
if finished.  
dblink_send_query connect with the own database and runs a long time.

When someone start the script again (when it is running), so I need a
section like:

if dblink_exists(updatesymbols)   -- but this function do not exists
then
return false -- or do nothing
end if;

dblink_is_busy is not usable: when the function is not running, it
stops.


2. question:
When dlink_send_query is running,
select dblink_get_connections()
send NULL as answer.


Franz




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Re: dblink_exists

David G Johnston
On Sunday, December 20, 2020, <[hidden email]> wrote:

My general problem:
I need a command that send a answer immediately and not, when the query
if finished. 


dblink_exec()?

 

When someone start the script again (when it is running), so I need a
section like:

Advisory locks?
 

2. question:
When dlink_send_query is running,
select dblink_get_connections()
send NULL as answer.


Don’t know - though suggest showing actual code that results in this behavior.

David J.
 
ml
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Re: dblink_exists

ml
On Sun, 2020-12-20 at 18:52 -0700, David G. Johnston wrote:
On Sunday, December 20, 2020, <[hidden email]> wrote:

My general problem:
I need a command that send a answer immediately and not, when the query
if finished. 
dblink_exec()?
  no, it needs a connection string
 

When someone start the script again (when it is running), so I need a
section like:
Advisory locks?
lock on a table: it is the  best solution  

2. question:
When dlink_send_query is running,
select dblink_get_connections()
send NULL as answer.

Don’t know - though suggest showing actual code that results in this behavior.

Franz