Before this change, count on a distributed returned NULL if all shards
were pruned away, because on the master we replace with count(..) call
with a sum(..) call to sum the counts from the shards. However, sum
returns NULL when there are no rows, whereas count is expected to return
0.
I had changed these callbacks to use the same method I chose for the
router executor (for consistency), but as that method is flawed, we now
want to ensure we directly register them from PG_init as well.
Not entirely sure why we went with the shared memory hook approach, but
it causes problems (multiple registration) during crashes. Changing to
a simple direct registration call from PG_init.
An interaction between ReraiseRemoteError and DML transaction support
causes segfaults:
* ReraiseRemoteError calls PurgeConnection, freeing a connection...
* That connection is still in the xactParticipantHash
At transaction end, the memory in the freed connection might happen to
pass the "is this connection OK?" check, causing us to try to send an
ABORT over that connection. By removing it from the transaction hash
before calling ReraiseRemoteError, we avoid this possibility.
UNIQUE or PRIMARY KEY constraints. Also, properly propagate valid
EXCLUDE constraints to worker shard tables.
If an EXCLUDE constraint includes the distribution column,
the operator must be an equality operator.
Tests in regression suite for exclusion constraints that include
the partition column, omit it, and include it but with non-equality
operator. Regression tests also verify that valid exclusion constraints
are propagated to the shard tables. And the tests work in different
timezones now.
Fixescitusdata/citus#748 and citusdata/citus#778.
pg_toast_* oids are constantly changing, and this causes regression tests to
fail time to time. With this commit, we remove all of the pg_toast_* references
from regression test outputs.
Three changes here to get to true multi-statement, multi-relation DDL
transactions (same functionality pre-5.2, with benefits of atomicity):
1. Changed the multi-shard utility hook to always run (consistency
with router executor hook, removes ad-hoc "installed" boolean)
2. Change the global connection list in multi_shard_transaction to
instead be a hash; update related functions to operate on global
hash instead of local hash/global list
3. Remove check within DDL code to prevent subsequent DDL commands;
place unset/reset guard around call to ConnectToNode to permit
connecting to additional nodes after DDL transaction has begun
In addition, code has been added to raise an error if a ROLLBACK TO
SAVEPOINT is attempted (similar to router executor), and comprehensive
tests execute all multi-DDL scenarios (full success, user ROLLBACK, any
actual errors (say, duplicate index), partial failure (duplicate index
on one node but not others), partial COMMIT (one node fails), and 2PC
partial PREPARE (one node fails)). Interleavings with other commands
(DML, \copy) are similarly all covered.
To permit use with ZomboDB (https://github.com/zombodb/zombodb), two
changes were necessary:
1. Permit use of `tableoid` system column in queries
2. Extend relation names appearing in index expressions
The first is accomplished by simply changing the deparse logic to allow
system columns in queries destined for distributed tables. The latter
was slightly more complex, given that DDL extension currently occurs on
workers. But since indexes cannot reference tables other than the one
being indexed, it is safe to look for any relation reference ending in
a '*' character and extend their penultimate segments with a shard id.
This change also adds an error to prevent users from distributing any
relations using the WITH (OIDS) feature, which is unsupported.
The call to hash_create specified HASH_CONTEXT without actually setting
one using the provided HASHCTL. The hashes returned by this function
are used locally, so simply using CurrentMemoryContext is sufficient.
In subquery pushdown, we allow outer joins if the join condition is on the
partition columns. WhereClauseList() used to return all join conditions including
outer joins. However, this has been changed with a commit related to outer join
support on regular queries. With this commit, we refactored ExtractFromExpressionWalker()
to return two lists of qualifiers. The first list is for inner join and filter
clauses and the second list is for outer join clauses. Therefore, we can also
use outer join clauses to check subquery pushdown prerequisites.
Before this change, we do not check whether given table which already contains any data
in master_create_distributed_table command. If that table contains any data, making it
it distributed, makes that data hidden to user. With this change, we now gave error to
user if the table contains data.
Jason Petersen
Marco Slot
Marco Slot
Jason Petersen
Burak Yücesoy
Murat Tuncer
Murat Tuncer
Metin Döşlü
Metin Doslu
Andres Freund
Eren Başak
Robin Thomas
Eric B. Ridge