When initializing a Citus formation automatically from an external piece of
software such as Citus-HA, the following process process may be used:
- decide on the groupId in the external software
- SELECT * FROM master_add_inactive_node('localhost', 9701, groupid => X)
When Citus checks for maxGroupId, it forbids other software to pick their
own group Ids to ues with the master_add_inactive_node() API.
This patch removes the extra testing around maxGroupId.
Description: Support round-robin `task_assignment_policy` for queries to reference tables.
This PR allows users to query multiple placements of shards in a round robin fashion. When `citus.task_assignment_policy` is set to `'round-robin'` the planner will use a round robin scheduling feature when multiple shard placements are available.
The primary use-case is spreading the load of reference table queries to all the nodes in the cluster instead of hammering only the first placement of the reference table. Since reference tables share the same path for selecting the shards with single shard queries that have multiple placements (`citus.shard_replication_factor > 1`) this setting also allows users to spread the query load on these shards.
For modifying queries we do not apply a round-robin strategy. This would be negated by an extra reordering step in the executor for such queries where a `first-replica` strategy is enforced.
The file handling the utility functions (DDL) for citus organically grew over time and became unreasonably large. This refactor takes that file and refactored the functionality into separate files per command. Initially modeled after the directory and file layout that can be found in postgres.
Although the size of the change is quite big there are barely any code changes. Only one two functions have been added for readability purposes:
- PostProcessIndexStmt which is extracted from PostProcessUtility
- PostProcessAlterTableStmt which is extracted from multi_ProcessUtility
A README.md has been added to `src/backend/distributed/commands` describing the contents of the module and every file in the module.
We need more documentation around the overloading of the COPY command, for now the boilerplate has been added for people with better knowledge to fill out.
Each PostgreSQL backend starts with a predefined amount of stack and this stack
size can be increased if there is a need. However, stack size increase during
high memory load may cause unexpected crashes, because if there is not enough
memory for stack size increase, there is nothing to do for process apart from
crashing. An interesting thing is; the process would get OOM error instead of
crash, if the process had an explicit memory request (with palloc) for example.
However, in the case of stack size increase, there is no system call to get OOM
error, so the process simply crashes.
With this change, we are increasing the stack size explicitly by requesting extra
memory from the stack, so that, even if there is not memory, we can at least get
an OOM instead of a crash.
In recent postgres builds you cannot set client_min_messages to
values higher then ERROR, if will silently set it to ERROR if so.
During some tests we would set it to fatal to hide random values
(eg. pid's of processes) from the test output. This patch will use
different tactics for hiding these values.
After Fast ALTER TABLE ADD COLUMN with a non-NULL default in PG11, physical heaps might not contain all attributes after a ALTER TABLE ADD COLUMN happens. heap_getattr() returns NULL when the physical tuple doesn't contain an attribute. So we should use heap_deform_tuple() in these cases, which fills in the missing attributes.
Our catalog tables evolve over time, and an upgrade might involve some ALTER TABLE ADD COLUMN commands.
Note that we don't need to worry about postgres catalog tables and we can use heap_getattr() for them, because they only change between major versions.
This also fixes#2453.
PG 11 has change the way that PARAM_EXTERN is processed.
This commit ensures that Citus follows the same pattern.
For details see the related Postgres commit:
6719b238e8
Assign the distributed transaction id before trying to acquire the
executor advisory locks. This is useful to show this backend in citus
lock graphs (e.g., dump_global_wait_edges() and citus_lock_waits).
I'm pretty sure a lot of this test functionality may be covered in some
of our existing regression tests, but I've included them to ensure we
put all failure-based tests under our new testing method for that kind
of test.
Didn't include lower replication factor, as (for a single-shard mod.),
it's indistinguishable from modifying a reference table. So these all
test modifications which hit a single, replicated shard.
We made PG11 builds optional when we had an issue
with mx isolation test that we could not solve back then.
This commit solves the issue with a workaround by running
start_metadata_sync_to_node outside the transaction block.
Both of these are a bit of a shot in the dark. In one case, we noticed
a stack trace where a caller received a null pointer and attempted to
dereference the memory context field (at 0x010). In the other, I saw
that any error thrown from within AdjustParseTree could keep the stack
from being cleaned up (presumably if we push we should always pop).
Both stack traces were collected during times of high memory pressure
and locally reproducing the problem locally or otherwise has been very
tricky (i.e. it hasn't been reproduced reliably at all).
* Keep track of cached entries in case of interruption.
Previously we set DistTableCacheEntry->sortedShardIntervalArray
and DistTableCacheEntry->shardIntervalArrayLength after we entered
all related shard entries into DistShardCacheHash. The drawback was
that if populating DistShardCacheHash was interrupted,
ResetDistTableCacheEntry() didn't see the shard hash entries created,
so was unable to clean them up.
This patch fixes that by setting sortedShardIntervalArray earlier,
and incrementing shardIntervalArrayLength as we enter shards into
the cache.
Murat Tuncer
Dimitri Fontaine
Marco Slot
Hanefi Onaldi
Onder Kalaci
Nils Dijk
Burak Yucesoy
Nils Dijk
Hadi Moshayedi
Jason Petersen
Hadi Moshayedi
velioglu