comparable to https://github.com/citusdata/tools/pull/88
this patch adds checks to the perl script running the testing harness of citus to start the postgres instances via the fixopen binary when present to work around `Interrupted System` call errors on OSX Big Sur.
Earlier versions of Citus (pre 9.0) had a bug where a user was able to get in a situation where a foreign key between two non-colocated tables was allowed. This was caused by the wrongful scoping together with only setting to on of a boolean variable in a loop, causing the `true` from an earlier iteration to leak into a new iteration.
This was 'by accident' solved in a refactor that was executed in the preparation of the 9.0 release. Only recently we had a user running into this and it was tracked down to this behaviour.
Given the dire situation a user could get them self into when running into this bug we have backported a fix to the latest 8.3 release branch.
To make sure this regression does not happen anymore in the future I propose we add the tests from the backport to our mainline.
For reference: https://github.com/citusdata/citus/pull/4840
With https://github.com/citusdata/citus/pull/4806 we enabled
2PC for any non-read-only local task. However, if the execution
is a single task, enabling 2PC (CoordinatedTransactionShouldUse2PC)
hits an assertion as we are not in a coordinated transaction.
There is no downside of using a coordinated transaction for single
task local queries.
Because setting the flag doesn't necessarily mean that we'll
use 2PC. If connections are read-only, we will not use 2PC.
In other words, we'll use 2PC only for connections that modified
any placements.
Before this commit, Citus used 2PC no matter what kind of
local query execution happens.
For example, if the coordinator has shards (and the workers as well),
even a simple SELECT query could start 2PC:
```SQL
WITH cte_1 AS (SELECT * FROM test LIMIT 10) SELECT count(*) FROM cte_1;
```
In this query, the local execution of the shards (and also intermediate
result reads) triggers the 2PC.
To prevent that, Citus now distinguishes local reads and local writes.
And, Citus switches to 2PC only if a modification happens. This may
still lead to unnecessary 2PCs when there is a local modification
and remote SELECTs only. Though, we handle that separately
via #4587.
Postgres keeps AFTER trigger state for each transaction, because we can have deferred AFTER triggers which will be fired at the end of a transaction. Postgres cleans up this state at the end of transaction.
Postgres processes ON COMMIT triggers after cleaning-up the AFTER trigger states. So if we fire any triggers in ON COMMIT, the AFTER trigger state won't be cleaned-up properly and the transaction state will be left in an inconsistent state, which might result in assertion failure.
So with this commit, we remove foreign keys between columnar metadata tables and enforce constraints between them manually when dropping columnar tables.
* Skip 2PC for readonly connections in a transaction
* Use ConnectionModifiedPlacement() function
* Remove the second check of ConnectionModifiedPlacement()
* Add order by to prevent flaky output
* Test using pg_dist_transaction
With this commit, we make sure to prevent infinite recursion for queries
in the format: [subquery with a UNION ALL] JOIN [table or subquery]
Also, fixes a bug where we pushdown UNION ALL below a JOIN even if the
UNION ALL is not safe to pushdown.
* Reimplement citus_update_table_statistics
* Update stats for the given table not colocation group
* Add tests for reimplemented citus_update_table_statistics
* Use coordinated transaction, merge with citus_shard_sizes functions
* Update the old master_update_table_statistics as well
* Use translated vars in postgres 13 as well
Postgres 13 removed translated vars with pg 13 so we had a special logic
for pg 13. However it had some bug, so now we copy the translated vars
before postgres deletes it. This also simplifies the logic.
* fix rtoffset with pg >= 13
/*
* The physical planner assumes that all worker queries would have
* target list entries based on the fact that at least the column
* on the JOINs have to be on the target list. However, there is
* an exception to that if there is a cartesian product join and
* there is no additional target list entries belong to one side
* of the JOIN. Once we support cartesian product join, we should
* remove this error.
*/
When executing alter_table / undistribute_table udf's, we should not try
to change sequence dependencies on MX workers if new table wouldn't
require syncing metadata.
Previously, we were checking that for input table. But in some cases, the
fact that input table requires syncing metadata doesn't imply the same
for resulting table (e.g when undistributing a Citus table).
Even more, doing that was giving an unexpected error when undistributing
a Citus table so this commit actually fixes that.
It seems that we need to consider only pseudo constants while doing some
shortcuts in planning. For example there could be a false clause but it
can contribute to the result in which case it will not be a pseudo
constant.
We would exclude tables without relationRestriction from conversion
candidates in local-distributed table joins. This could leave a leftover
local table which should have been converted to a subquery.
Ideally I would expect that in each call to CreateDistributedPlan we
would pass a new plan id, but that seems like a bigger change.
/*
* Colocated intermediate results are just files and not required to use
* the same connections with their co-located shards. So, we are free to
* use any connection we can get.
*
* Also, the current connection re-use logic does not know how to handle
* intermediate results as the intermediate results always truncates the
* existing files. That's why, we use one connection per intermediate
* result.
*/
We do not include dummy column if original task didn't return any
columns.
Otherwise, number of columns that original task returned wouldn't
match number of columns returned by worker_save_query_explain_analyze.
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