Thread: asynchronous support

Hi,

I  wanted to lock a table from one application and insert some data. And my requirement is, if that table is already locked by anyother process then I need to try to lock after a specific amount of time.

I am using unixODBC driver in centOS machine and my database is postgresql. I did a research on how to execute a sql asynchronously using odbc api. I found SQLSetStmtAttr api can be used to execute the sql statement asynchronously. But its not working. 

This is how I wrote the code 

ret =  SQLSetStmtAttr( stmt1,  SQL_ATTR_ASYNC_ENABLE,(SQLPOINTER) SQL_ASYNC_ENABLE_ON, 0);

// above statement returned 0 which means success


 if((ret = SQLExecDirect(stmt1,"lock table test",SQL_NTS)) == SQL_STILL_EXECUTING)

  {

     printf("\nCanceling\n");

     ret = SQLCancel(stmt);

  }

But process is getting hang on SQLExecDirect api, as that table "test" is already locked by another process. (Hang in the sense, waiting for all other processes to release the lock)

Why is it so ? Is that because my unixODBC driver does not support asynchronous execution. if its so why SQLSetStmtAttr is returning success ?

Any help is greatly appreciated. Thanks in advance.