On Wed, Dec 6, 2017 at 9:35 AM, Mark Dilger <hornschnor...@gmail.com> wrote: >> On Dec 5, 2017, at 11:25 AM, Thomas Munro <thomas.mu...@enterprisedb.com> >> wrote: >> Does the plan have multiple Gather nodes with Parallel Bitmap Heap Scan? > > This was encountered and logged by a java client. The only data I got was: > > org.postgresql.util.PSQLException: ERROR: dsa_allocate could not find 4 free > pages > Where: parallel worker
This means that the DSA area is corrupted. Presumably get_best_segment(area, 4) returned a segment that wasn't actually good for 4 pages, either because it was incorrectly binned or because its free space btree was corrupted. Another path would be that make_new_segment(area, 4) returned a segment that couldn't find 4 pages, but that seems unlikely. > [query plan with one Gather and no Parallel Bitmap Heap Scan] I'm not sure why this plan would ever call dsa_allocate(). > [query plan with no Gather but plenty of Btimap Heap Scans] And this one certainly can't. I guess you must sometimes get a different variation that has Gather nodes and uses Parallel Bitmap Heap Scan. Then the question is whether the es_query_dsa multiple Gather bug can explain this: for example, if dsa_free(wrong_dsa_area, p) was called, perhaps it could produce this type of corruption. Otherwise we have a different bug. Any clues on how to reproduce the problem would be very welcome. -- Thomas Munro http://www.enterprisedb.com
