On Wed, May 2, 2018 at 10:43 AM, Heikki Linnakangas <hlinn...@iki.fi> wrote: > I'm not sure what you could derive that from, to make it less arbitrary. At > the moment, I'm thinking of just doing something like this: > > /* > * Minimum amount of memory reserved to hold the sorted tuples in > * TSS_BUILDRUNS phase. This specifies a minimum size for the merge runs, > * when work_mem is very small. > */ > #define MIN_TUPLE_MEMORY (32 * 1024)
If you end up doing something like this, I suggest that you also change this code to simply assign 1024 (or maybe a new preprocessor constant): state->memtupsize = Max(1024, ALLOCSET_SEPARATE_THRESHOLD / sizeof(SortTuple) + 1); The ALLOCSET_SEPARATE_THRESHOLD part can become a static assertion. -- Peter Geoghegan
