Michael Lewis schrieb am 08.01.2021 um 16:32:
On Fri, Jan 8, 2021 at 2:36 AM Thomas Kellerer <shammat@xxxxxxx <mailto:shammat@xxxxxxx>> wrote:
Hello,
I wonder if it made sense to add a "TRUNCATE PARTITION" command to Postgres?
Especially during bulk loads it's more efficient to TRUNCATE a partition if I know I want to replace all rows, rather than doing a DELETE.
Currently this requires dynamic SQL which isn't always feasible (and might get complicated quickly).
So I was thinking that a new command to allow truncating partitions by identifying the partitions by "value" rather by name might be helpful in that case.
Something along the lines of:
truncate partitions of base_table
for values in (...);
If the IN part allowed for sub-queries then this could be used to gather the partition keys from e.g. a staging table.
For me, it seems too easily error prone such that a single typo in
the IN clause may result in an entire partition being removed that
wasn't supposed to be targeted.
I don't see how this is more dangerous then:
delete from base_table
where partition_key in (...);
which would serve the same purpose, albeit less efficient.
Given the user still needs to
manually generate that list somehow, I don't see it as a huge effort
to query the partitions and run individual commands to truncate or
detach several partitions manually.
Well, the list could come from e.g. a staging table, e.g. "for values IN (select some_column from staging_table)"
