DESCRIPTION: Fixes a bug in background shard rebalancer where the
replicate reference tables task fails if the current user is not a
superuser.
This change is to be backported to earlier releases. We should fix the
permissions for replicate_reference_tables on main branch such that it
can be run by non-superuser roles.
Fixes#6925.
Fixes#6926.
(cherry picked from commit f9a5be59b9)
DESCRIPTION: This PR removes the task dependencies between shard moves
for which the shards belong to different colocation groups. This change
results in scheduling multiple tasks in the RUNNABLE state. Therefore it
is possible that the background task monitor can run them concurrently.
Previously, all the shard moves planned in a rebalance operation took
dependency on each other sequentially.
For instance, given the following table and shards
colocation group 1 colocation group 2
table1 table2 table3 table4 table 5
shard11 shard21 shard31 shard41 shard51
shard12 shard22 shard32 shard42 shard52
if the rebalancer planner returned the below set of moves
` {move(shard11), move(shard12), move(shard41), move(shard42)}`
background rebalancer scheduled them such that they depend on each other
sequentially.
```
{move(reftables) if there is any, none}
|
move( shard11)
|
move(shard12)
| {move(shard41)<--- move(shard12)} This is an artificial dependency
move(shard41)
|
move(shard42)
```
This results in artificial dependencies between otherwise independent
moves.
Considering that the shards in different colocation groups can be moved
concurrently, this PR changes the dependency relationship between the
moves as follows:
```
{move(reftables) if there is any, none} {move(reftables) if there is any, none}
| |
move(shard11) move(shard41)
| |
move(shard12) move(shard42)
```
---------
Co-authored-by: Jelte Fennema <jelte.fennema@microsoft.com>
DESCRIPTION: Fix background rebalance when reference table has no PK
For the background rebalance we would always fail if a reference table
that was not replicated to all nodes would not have a PK (or replica
identity). Even when we used force_logical or block_writes as the shard
transfer mode. This fixes that and adds some regression tests.
Fixes#6680
No need for description, fixing issue introduced with new feature for
11.1
Fixes#6333
Due to Postgres' C api being o-indexed and postgres' attributes being
1-indexed, we were reading the wrong Datum as the Task owner when
cancelling. Here we add a test to show the error and fix the off-by-one
error.
DESCRIPTION: Add a rebalancer that uses background tasks for its
execution
Based on the baclground jobs and tasks introduced in #6296 we implement
a new rebalancer on top of the primitives of background execution. This
allows the user to initiate a rebalance and let Citus execute the long
running steps in the background until completion.
Users can invoke the new background rebalancer with `SELECT
citus_rebalance_start();`. It will output information on its job id and
how to track progress. Also it returns its job id for automation
purposes. If you simply want to wait till the rebalance is done you can
use `SELECT citus_rebalance_wait();`
A running rebalance can be canelled/stopped with `SELECT
citus_rebalance_stop();`.
Emel Şimşek
Jelte Fennema
Ahmet Gedemenli
Nils Dijk