Adds support for PostgreSQL 9.6 by copying in the requisite ruleutils
file and refactoring the out/readfuncs code to flexibly support the
old-style copy/pasted out/readfuncs (prior to 9.6) or use extensible
node APIs (in 9.6 and higher).
Most version-specific code within this change is only needed to set new
fields in the AggRef nodes we build for aggregations. Version-specific
test output files were added in certain cases, though in most they were
not necessary. Each such file begins by e.g. printing the major version
in order to clarify its purpose.
The comment atop citus_nodes.h details how to add support for new nodes
for when that becomes necessary.
This change adds the pg_dist_local_group metadata table, which indicates
the group id of the current node. It is expected that this table contains
one and only one row, which only contains the group id of the node as an
integer.
With this change, master_copy_shard_placement and master_move_shard_placement functions
start to copy/move given shard along with its co-located shards.
This commit completes having support in Citus by adding having support for
real-time and task-tracker executors. Multiple tests are added to regression
tests to cover new supported queries with having support.
This change adds the required infrastructure about metadata snapshot from MX
codebase into Citus, mainly metadata_sync.c file and master_metadata_snapshot UDF.
Two sets of tests are fixed by this change:
* multi_agg_approximate_distinct
* those in multi_task_tracker_extra_schedule
The first broke when we renamed stage to load in many files and was
never being run because the HyperLogLog extension wasn't easily
available in Debian. Now it's in our repo, so we install it and run
the test. I removed the distinct HLL target in favor of just always
running it and providing an output variant to handle when the extension
is absent. Basically, if PostgreSQL thinks HLL is available, the test
installs it and runs normally, otherwise the absent variant is used.
The second broke when I removed a test variant, erroneously believing
it to be related to an older Citus version. I've added a line in that
test to clarify why the variant is necessary (a practice we should
widely adopt).
So far placements were assigned an Oid, but that was just used to track
insertion order. It also did so incompletely, as it was not preserved
across changes of the shard state. The behaviour around oid wraparound
was also not entirely as intended.
The newly introduced, explicitly assigned, IDs are preserved across
shard-state changes.
The prime goal of this change is not to improve ordering of task
assignment policies, but to make it easier to reference shards. The
newly introduced UpdateShardPlacementState() makes use of that, and so
will the in-progress connection and transaction management changes.
Related to #786
This change adds the `pg_dist_node` table that contains the information
about the workers in the cluster, replacing the previously used
`pg_worker_list.conf` file (or the one specified with `citus.worker_list_file`).
Upon update, `pg_worker_list.conf` file is read and `pg_dist_node` table is
populated with the file's content. After that, `pg_worker_list.conf` file
is renamed to `pg_worker_list.conf.obsolete`
For adding and removing nodes, the change also includes two new UDFs:
`master_add_node` and `master_remove_node`, which require superuser
permissions.
'citus.worker_list_file' guc is kept for update purposes but not used after the
update is finished.