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 cre

ate a temporary set, add the new objects to that, subscribe all

nodes currently subscribed to the other set to this new one, and

then merge the two together, eliminating the set ID that was be

ing 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 separate sets.

ADD ID = ival

Unique ID of the set whose objects should be trans

ferred.

ORIGIN = ival

Current origin node for both sets.

This uses .

EXAMPLE

# Assuming that set 1 has direct subscribers 2 and 3
SUBSCRIBE SET (ID = 999, PROVIDER = 1, RECEIVER = 2);
WAIT FOR EVENT (ORIGIN = 2, CONFIRMED = 1);
SYNC (ID=1);
SUBSCRIBE SET (ID = 999, PROVIDER = 1, RECEIVER = 3);
WAIT FOR EVENT (ORIGIN = 3, CONFIRMED = 1);
SYNC (ID=1);
MERGE SET ( ID = 2, ADD ID = 9999, ORIGIN = 1 );

LOCKING BEHAVIOUR

No application-visible locking should take place.

DANGEROUS/UNINTUITIVE BEHAVIOUR

Merging takes place based on the configuration on the ori

gin node. If a merge is requested while subscriptions are still

being processed, this can cause in-progress subscribers' replica

tion 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.

VERSION INFORMATION

This command was introduced in Slony-I 1.0.5. In 1.2.1, a

race condition was rectified where the merge request would be

submitted while subscriptions were still in process on sub

scribers; it refuses to merge before subscriptions are complete.

MERGE

SET(7)