Add support for continuous aggregates for distributed hypertables by
allowing a continuous aggregate to read from a distributed hypertable
so that the continuous aggregate is on the access node while the
hypertable data is on the data nodes.
For distributed hypertables, both the hypertable and continuous
aggregate invalidation log are kept on the data nodes and the refresh
window is computed at refresh time on each data node. Since the
continuous aggregate materialization hypertable is not present on the
data nodes, the invalidation log was extended to allow using a
non-local hypertable id on the data nodes. This means that you cannot
create continuous aggregates on the data nodes since those could clash
with continuous aggregates on the access node.
Some utility statements added entries to the invalidation logs
directly (truncating chunks and hypertables, as well as dropping
individual chunks), so to handle this case, internal functions were
added to allow logging invalidation on the data nodes from the access
node.
The commit also includes some fixes to memory context usage that
caused crashes for invalidation triggers and also disable per data
node queries during refresh since that would otherwise generate an
exception.
Fixes#3435
Co-authored-by: Mats Kindahl <mats@timescale.com>
A new view in the experimental schema shows information related to
chunk replication. The view can be used to learn the replication
status of a chunk while also providing a way to easily find nodes to
move or copy chunks between in order to ensure a fully replicated
multi-node cluster.
Tests have been added to illustrate the potential usage.
This commit add functions and code to generate a downgrade script from
the current version to the previous version. This requires execution
from a Git repository since it retrieves the prolog and epilog for the
"downgrade" file from the version given by `update_from_version` in the
`version.config` file.
The commit adds several CMake functions that simplifies the composition
of script files, but these are not used to generate the update scripts.
A potential improvement is to use the scripts to also generate the
update scripts.
This commit supports generating a downgrade script from the
current version to the previous version. Other versions are handled
using a variable containing file names of reverse update
scripts and the source and target version is extracted from the file
names, which is assumed to be of the form
`<source-version>--<target-version>.sql`.
In addition to adding support for generating downgrade scripts, the
commit adds a downgrade test file that tests a release in a similar way
to the update script and adds it as a workflow.
