Hi

we see a lot of problems lately because the measurements compression does a truncate of tables which actually takes a couple of hours.

Can you please implement a different truncation mechanism to avoid these long running truncate statements.

As far as I've seen there is no foreign key dependency in the "qb_measurement_datarXX" tables so it should be possible to just do the following steps in a single transaction:
1. lock qb_measurement_datarXX row exclusive via: LOCK TABLE qb_measurement_datarXX IN ROW EXCLUSIVE mode;
2. create a new table with a name like "qb_measurement_datarXX_new" with: CREATE TABLE qb_measurement_datarXX_new (LIKE qb_measurement_datarXX)
3. rename the table to something like "qb_measurement_datarXX_old" with: ALTER TABLE qb_measurement_datarXX RENAME TO qb_measurement_datarXX_old
4. rename the new table to "qb_measurement_datarXX" via: ALTER TABLE qb_measurement_datarXX_new RENAME TO qb_measurement_datarXX
5. commit the changes (unlocks the table and finishes the transaction)
6. start DROP TABLE qb_measurement_datarXX in the background

as creating a new table and the renaming just takes seconds and not hours this would not interrupt the operation for that long. And the DROP TABLE can just run out of process as it is not used in any way.
If there is some concern that the new table name could interrupt with something a generated name for just this purpose would also suffice.

And just to clarify what's meaning long execution time, the log line is as follows:
Finished truncating dead table [MeasurementDataR00], [0] rows removed in [5339615] millis

here 0 means that truncate is used because TRUNCATE basically does not return the exact amount of rows deleted. And it took around 1.5 hours to just execute the TRUNCATE.