On 7 August 2018 at 13:47, Andres Freund <and...@anarazel.de> wrote: > Hi, > > On 2018-08-08 00:40:12 +1200, David Rowley wrote: >> 1. Obtain a ShareUpdateExclusiveLock on the partitioned table rather >> than an AccessExclusiveLock. >> 2. Do all the normal partition attach partition validation. >> 3. Insert pg_partition record with partvalid = true. >> 4. Invalidate relcache entry for the partitioned table >> 5. Any loops over a partitioned table's PartitionDesc must check >> PartitionIsValid(). This will return true if the current snapshot >> should see the partition or not. The partition is valid if partisvalid >> = true and the xmin precedes or is equal to the current snapshot. > > How does this protect against other sessions actively using the relcache > entry? Currently it is *NOT* safe to receive invalidations for > e.g. partitioning contents afaics.
I think you may be right in the general case, but ISTM possible to invalidate/refresh just the list of partitions. If so, that idea would seem to require some new, as-yet not invented mechanism. -- Simon Riggs http://www.2ndQuadrant.com/ PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services
