Transactions

[Phillip B Oldham]

I note that Hypertable has had "simple row/range level transaction
support" since the 0.9.1.0. Reading the issue report, this doesn't
seem to be something usable from the "client" side.

Will transactions, as in committing a number of cell updates at once
and rolling back if unsuccessful, be available in Hypertable? If so,
what release is this planned for?

[Luke]

On Tue, Jun 16, 2009 at 5:11 AM, Phillip B
Oldham<phillip...@gmail.com> wrote:
>
> I note that Hypertable has had "simple row/range level transaction
> support" since the 0.9.1.0. Reading the issue report, this doesn't
> seem to be something usable from the "client" side.
> Will transactions, as in committing a number of cell updates at once
> and rolling back if unsuccessful, be available in Hypertable?

It's implemented in the sense that if "set_cells" calls contain
multiple cell updates to the same row and return successfully, the
transaction is considered successful (the update is sync'ed to commit
log and in memory data structure is updated accordingly.) Otherwise
the whole update is not applied. This behavior relies on the
assumption that dfs sync failures imply incomplete update in the
commit log that would be skipped upon recovery. We thought the
assumption is "reasonable" for most dfs implementations. But one can
argue certain rare corner cases (especially when involving
replication), where a sync can return failure but dfs would retain a
full update which would be reapply upon recovery.

> If so, what release is this planned for?

General transaction support (with multiple rows) is planned post 1.0.
Probably 1.1. People/org can vote with their money to bump up its
priority :)

__Luke