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4.19.2 Out-of-Band Attention Signal

  • Artikkeli

In this example, a SQL statement is sent to the server, yet before all the data has been returned an interrupt or "Attention Signal" is sent to the server. The client reads and discards any data received between the time the interrupt was sent and the interrupt acknowledgment was received. The interrupt acknowledgment from the server is a bit set in the status field of the DONE token.

 Client:    select name, empid from employees
  
 Server:    COLMETADATA   data stream
            ROW           data stream
            .
            .
            ROW           data stream
  
 Client:    ATTENTION SENT

[The client reads and discards any data already buffered by the server until the acknowledgment is found. There might be or might not be a DONE token with the DONE_MORE bit clear prior to the DONE token with the DONE_ATTN bit set.]

 Server:    DONE          data stream (with DONE_ATTN bit set)