SLONIK MERGE SET(7) Configuration and Action commands SLONIK MERGE SET(7)NAME
MERGE SET - Merge Slony-I replication sets together
SYNOPSIS
MERGE SET (options);
DESCRIPTION
Merge a set of tables and sequences into another one. This function is
a workaround for the problem that it is not possible to add
tables/sequences to already-subscribed sets. One may create a temporary
set, add the new objects to that, subscribe all nodes currently sub‐
scribed to the other set to this new one, and then merge the two
together, eliminating the set ID that was being added.
This operation will refuse to be run if the two sets do not have
exactly the same set of subscribers.
ID = ival
Unique ID of the set to contain the union of the two formerly
separate sets.
ADD ID = ival
Unique ID of the set whose objects should be transferred into
the above set.
ORIGIN = ival
Current origin node for both sets.
This uses mergeset(integer,integer) .
EXAMPLE
# Assuming that node 1 is the origin of set 999 that has direct subscribers 2 and 3
SUBSCRIBE SET (ID = 999, PROVIDER = 1, RECEIVER = 2);
SUBSCRIBE SET (ID = 999, PROVIDER = 1, RECEIVER = 3);
MERGE SET ( ID = 1, ADD ID = 999, ORIGIN = 1 );
LOCKING BEHAVIOUR
No application-visible locking should take place.
DANGEROUS/UNINTUITIVE BEHAVIOUR
Merging takes place based on the configuration on the origin node. If
a merge is requested while subscriptions are still being processed,
this can cause in-progress subscribers' replication to break, as
they'll be looking for configuration for this set which the merge
request deletes. Do not be too quick to merge sets.
SLONIK EVENT CONFIRMATION BEHAVIOUR
Slonik waits for the command submitted to the previous event node to be
confirmed on the specified event node before submitting this command.
Slonik will also wait for any in progress subscriptions involving the
ADD ID to be subscribed before submitting the MERGE SET command.
VERSION INFORMATION
This command was introduced in Slony-I 1.0.5. In 1.2.1, a race condi‐
tion was rectified where the merge request would be submitted while
subscriptions were still in process on subscribers; it refuses to merge
before subscriptions are complete.
18 January 2015 SLONIK MERGE SET(7)
