DESCRIPTION: Fix counter that keeps track of internal depth in executor
While reviewing #3302 I ran into the `ExecutorLevel` variable which used a variable to keep the original value to restore on successful exit. I haven't explored the full space and if it is possible to get into an inconsistent state. However using `PG_TRY`/`PG_CATCH` seems generally more correct.
Given very bad things will happen if this level is not reset, I kept the failsafe of setting the variiable back to 0 on the `XactCallback` but I did add an assert to treat it as a developer bug.
Previously,
- we'd push down ORDER BY, but this doesn't order intermediate results between workers
- we'd keep FILTER on master aggregate, which would raise an error about unexpected cstrings
Initialization of queryWindowClause and queryOrderByLimit "memset" underflow these variables.
It's possible due to the invalid usage sizeof this part of the program cause buffer overflow and function return data corruption in future changes.
* Improve extension command propagation tests
* patch for hardcoded citus extension name
(cherry picked from commit 0bb3dbac0afabda10e8928f9c17eda048dc4361a)
In plain words, each distributed plan pulls the necessary intermediate
results to the worker nodes that the plan hits. This is primarily useful
in three ways.
(i) If the distributed plan that uses intermediate
result(s) is a router query, then the intermediate results are only
broadcasted to a single node.
(ii) If a distributed plan consists of only intermediate results, which
is not uncommon, the intermediate results are broadcasted to a single
node only.
(iii) If a distributed query hits a sub-set of the shards in multiple
workers, the intermediate results will be broadcasted to the relevant
node(s).
The final item (iii) becomes crucial for append/range distributed
tables where typically the distributed queries hit a small subset of
shards/workers.
To do this, for each query that Citus creates a distributed plan, we keep
track of the subPlans used in the queryTree, and save it in the distributed
plan. Just before Citus executes each subPlan, Citus first keeps track of
every worker node that the distributed plan hits, and marks every subPlan
should be broadcasted to these nodes. Later, for each subPlan which is a
distributed plan, Citus does this operation recursively since these
distributed plans may access to different subPlans, and those have to be
recorded as well.
Prevent Citus extension being distributed
Because that could prevent doing rolling upgrades, where users may
prefer to upgrade the version on the coordinator but not the workers.
There could be some other edge cases, so I'd prefer to keep Citus
extension outside the picture for now.
Hanefi Onaldi
Jelte Fennema
Onur TIRTIR
Nils Dijk
Marco Slot
Hadi Moshayedi
Hadi Moshayedi
Philip Dubé
Önder Kalacı
Khashayar Fereidani
Philip Dubé
Marco Slot
SaitTalhaNisanci
Halil Ozan Akgül