NAME

       WAIT FOR EVENT - Have Slonik script wait for previous event to complete

SYNOPSIS

       WAIT FOR EVENT (options);

DESCRIPTION

       Waits for event Confirmation.

       Slonik  remembers  the  last event generated on every node during script execution (events
       generated by earlier calls are  currently  not  checked).  In  certain  situations  it  is
       necessary  that events generated on one node (such as CREATE SET) are processed on another
       node before issuing more commands (for instance, SLONIK SUBSCRIBE SET(7)). WAIT FOR  EVENT
       may  be  used  to  cause  the  slonik  script  to wait for confirmation of an event, which
       hopefully means that the subscriber node is ready for the next action.

       WAIT FOR EVENT must be called outside of any try block in order to work, since new confirm
       messages don't become visible within a transaction.

       ORIGIN = ival | ALL
              The origin of the event(s) to wait for.

       CONFIRMED = ival | ALL
              The node ID of the receiver that must confirm the event(s).

       WAIT ON = ival
              The ID of the node where the “sl_confirm” [not available as a man page] table is to
              be checked.

       TIMEOUT = ival
              The number of seconds to wait. Default is 600 (10 minutes). TIMEOUT = 0 causes  the
              script to wait indefinitely.

EXAMPLE

       WAIT FOR EVENT (
         ORIGIN = ALL,
         CONFIRMED = ALL,
         WAIT ON = 1
       );

LOCKING BEHAVIOUR

       No application-visible locking should take place.

VERSION INFORMATION

       This command was introduced in Slony-I 1.0

       In version 2.0, the default value for WAIT ON was removed, so a node must be specified.

ODDITIES

       Not  all  events  return  interesting results. For instance, many people have run afoul of
       problems with SLONIK SUBSCRIBE SET(7), when subscribing a new set. Be aware (and  beware!)
       that  a  SLONIK  SUBSCRIBE  SET(7)  request  will  return  the  event  confirmation almost
       immediately, even  though  there  might  be  several  hours  of  work  to  do  before  the
       subscription is ready. The trouble with SLONIK SUBSCRIBE SET(7) is that it is processed as
       two events, one on the origin node, with a second event, to enable  the  subscription,  on
       the subscriber.

       In  order  to  more  reliably monitor from within a slonik(1) script that SLONIK SUBSCRIBE
       SET(7) is complete, you may submit a SLONIK SYNC(7) event after the subscription, and have
       the WAIT request wait on the SYNC event, as follows.

            # Assuming that node 1 is the origin for set 999 that has direct subscribers 2 and 3
            SUBSCRIBE SET (ID = 999, PROVIDER = 1, RECEIVER = 2);
            WAIT FOR EVENT (ORIGIN = 1, CONFIRMED = ALL, WAIT ON=1);
            SUBSCRIBE SET (ID = 999, PROVIDER = 1, RECEIVER = 3);
            WAIT FOR EVENT (ORIGIN = 1, CONFIRMED = ALL, WAIT ON=1);
            MERGE SET ( ID = 1, ADD ID = 999, ORIGIN = 1 );

                                         1 November 2021                 SLONIK WAIT FOR EVENT(7)