It seems that we were not considering the case where coordinator was
added to the cluster as a worker in the optimization of intermediate
results.
This could lead to errors when coordinator was added as a worker.
pg_get_tableschemadef_string doesn't know how to deparse identity
columns so we cannot reflect those columns when creating table
from scratch. For this reason, we don't allow using alter_table udfs
with tables having any identity cols.
pg_get_tableschemadef_string doesn't know how to deparse identity
columns so we cannot reflect those columns when creating shell
relation.
For this reason, we don't allow adding local tables -having identity cols-
to metadata.
Postgres doesn't allow inserting into columns having GENERATED ALWAYS
AS (...) STORED expressions.
For this reason, when executing undistribute_table or an alter_* udf,
we should skip copying such columns.
This is not bad since Postgres would already generate such columns.
Enables an overall plan to be parallel (e.g. over a partition
hierarchy), even though an individual ColumnarScan is not
parallel-aware.
Co-authored-by: Jeff Davis <jefdavi@microsoft.com>
Previously, if columnar.enable_custom_scan was false, parallel paths
could remain, leading to an unexpected error.
Also, ensure that cheapest_parameterized_paths is cleared if a custom
scan is used.
Co-authored-by: Jeff Davis <jefdavi@microsoft.com>
When finding columns owning sequences, we shouldn't rely on atthasdef
since it might be true when column has GENERATED ALWAYS AS (...)
STORED expression.
* Fix partition column index issue
We send column names to worker_hash/range_partition_table methods, and
in these methods we check the column name index from tuple descriptor.
Then this index is used to decide the bucket that the current row will
be sent for the repartition.
This becomes a problem when there are the same column names in the
tupleDescriptor. Then we can choose the wrong index. Hence the
partitioned data will be put to wrong workers. Then the result could
miss some data because workers might contain different range of data.
An example:
TupleDescriptor contains "trip_id", "car_id", "car_id" for one table.
It contains only "car_id" for the other table. And assuming that the
tables will be partitioned by car_id, it is not certain what should be
used for deciding the bucket number for the first table. Assuming value
2 goes to bucket 2 and value 3 goes to bucket 3, it is not certain which
bucket "1 2 3" (trip_id, car_id, car_id) row will go to.
As a solution we send the index of partition column in targetList
instead of the column name.
The old API is kept so that if workers upgrade work, it still works
(though it will have the same bug)
* Use the same method so that backporting is easier
Fixing a division by zero in the cost calculations for scanning a columnar table.
Due to how the columns in a columnar table are counted an empty table would result in a division by zero. Instead this patch keeps the column selection ratio on zero when this happens, resulting in an accurate cost of zero pages to scan a columnar table.
fixes#4589
* Make undistribute_table() and citus_create_local_table() work with columnar
* Rename and use LocallyExecuteUtilityTask for UDF check
* Remove 'local' references in ExecuteUtilityCommand
/*
* Creating Citus local tables relies on functions that accesses
* shards locally (e.g., ExecuteAndLogDDLCommand()). As long as
* we don't teach those functions to access shards remotely, we
* cannot relax this check.
*/
The reason behind skipping postgres tables is that we support
foreign keys between postgres tables and reference tables
(without converting postgres tables to citus local tables)
when enable_local_reference_table_foreign_keys is false or
when coordinator is not added to metadata.
When enabled any foreign keys between local tables and reference
tables supported by converting the local table to a citus local
table.
When the coordinator is not in the metadata, the logic is disabled
as foreign keys are not allowed in this configuration.
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