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
In pg11.8 it seemingly tries to parse the full sql file creating the extension,
since we use syntax introduced in postgres 12 this fails.
This patch rewrites the statement not recognized by pg11.8 to be dynamically
executed from a string literal via `EXECUTE`.
* Make undistribute_table() and citus_create_local_table() work with columnar
* Rename and use LocallyExecuteUtilityTask for UDF check
* Remove 'local' references in ExecuteUtilityCommand
As described in the comment, we have observed crashes in production
due to a segfault caused by the dereference of a NULL pointer in our
connection statemachine.
As a mitigation, preventing system crashes, we provide an error with
a small explanation of the issue. Unfortunately the case is not
reliably reproduced yet, hence the inability to add tests.
DESCRIPTION: Prevent segfaults when SAVEPOINT handling cannot recover from connection failures
Currently we choose an arbitrary colocation id from all the matches for
a colocation id. This could mean that 2 distributed tables, which have
the same scheme could go into different colocation groups. This fix
makes sure that the same match will go to the same colocation group.
/*
* 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.
*/
Logical replication status can take wal_receiver_status_interval
seconds to get updated. Default is 10s, which means tests in
which logical replication is used can take a long time to finish.
We reduce it to 1 second to speed these tests up.
Logical replication apply launcher launches workers every
wal_retrieve_retry_interval, so if we have many shard moves with
logical replication consecutively, they will be throttled by this
parameter. Default is 5s, we reduce it to 1s so we finish tests
faster.