[Bucardo-general] replicating "transactions" "consistently"

Greg Sabino Mullane greg at endpoint.com
Fri Nov 21 16:29:21 UTC 2008

> Lets have 2 dbs what get synchronized with bucardo. Lets define 3 tables
> on master and slave. Lets define an sql transaction on master, what when
> it commits, causes changes in all of that 3 tables. Lets define a select
> query on slave db, with outcome data from all the 3 tables.
> Can i configure so bucardo, that i cant have inconsistent selects on
> slave side?

That is the default - if all three table are in the same sync, the slave
will be updated withing a single transaction. Note that there is no 
guarantee that multiple slaves will be in exact sync with each other, but
all the tables within a particular slave will be fine.

> Other: It is possible to have bucardo replicate changes from multiple
> tables in one transaction? (on slave)

Yes: typically a sync has a source herd, which maps to multiple tables
(goats) via the herdmap table.

> Other: before the sync my slave-select provides consistent data, after
> the sync my slave-select provides consitent data, until the sync process
> it is possible such select, that reads from one table old data, and from
> the other 2 tables new data?

No, the tables are replicated to the slave within a single transaction.

> And a more deepgoing one: if i have a herd, with multiple tables(goats)
> pushdelta synchronized, and there are changes in one of the goats, then
> the synchronizing process picks up automatically all changes from the
> other goats too, and will all those actually-nown changes synchronized
> to slave db in one transaction, or with multiple transactions?

One transaction.

Greg Sabino Mullane greg at endpoint.com
End Point Corporation
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