Text datums can't be directly accessed via the struct equivalence trick
used to access catalogs. That's because, as an optimization, they're
sometimes aligned to 1 byte ("text"'s alignment), and sometimes to 4
bytes. That depends on it being a short
varlena (cf. VARATT_NOT_PAD_BYTE) or not.
In the case at hand here, partkey became longer than 127 characters -
the boundary for short varlenas (cf. VARATT_CAN_MAKE_SHORT()). Thus it
became 4 byte/int aligned. Which lead to the direct struct access
accessing the wrong data.
The fix is simply to never access partkey that way - to enforce that,
hide partkey ehind the usual ifdef.
Fixes: #674
Previously several commands, amongst them commands like
master_create_distributed_table(), were allowed for everyone. That's not
good: Even though citus currently requires superuser permissions, we
shouldn't allow non-superusers to perform actions as sensitive as making
a table distributed.
There's no checks on the worker_* functions, as these usually just punt
the action to underlying postgres functionality, which then perform the
necessary checks.
So far we've always used libpq defaults when connecting to workers; bar
special environment variables being set that'll always be the user that
started the server. That's not desirable because it prevents using
users with fewer privileges.
Thus change the various APIs creating connections to workers to always
use usernames. That means:
1) MultiClientConnect() needs to, optionally, accept a username
2) GetOrEstablishConnection(), including the underlying cache, need to
use the current user as part of the connection cache key. That way
connections for separate users are distinct, and we always use one
with the correct authorization.
3) The task tracker needs to keep track of the username associated with
a task, so it can use it when establishing connections outside the
originating session.
This commit adds a fast shard pruning path for INSERTs on
hash-partitioned tables. The rationale behind this change is
that if there exists a sorted shard interval array, a single
index lookup on the array allows us to find the corresponding
shard interval. As mentioned above, we need a sorted
(wrt shardminvalue) shard interval array. Thus, this commit
updates shardIntervalArray to sortedShardIntervalArray in the
metadata cache. Then uses the low-level API that is defined in
multi_copy to handle the fast shard pruning.
The performance impact of this change is more apparent as more
shards exist for a distributed table. Previous implementation
was relying on linear search through the shard intervals. However,
this commit relies on constant lookup time on shard interval
array. Thus, the shard pruning becomes less dependent on the
shard count.
When we notice that pg_dist_partition is being invalidated we assume
that the citus extension is being dropped and drop state such as
extensionLoaded and the cached oids of all the metadata tables.
This frees the user from needing to reconnect after running DROP
EXTENSION, so we also no longer send a warning message.
All citusdb references in
- extension, binary names
- file headers
- all configuration name prefixes
- error/warning messages
- some functions names
- regression tests
are changed to be citus.
Burak Yucesoy
Andres Freund
Murat Tuncer
Onder Kalaci
Brian Cloutier
Jason Petersen
Marco Slot