On 2021/05/14 17:00, Masahiro Ikeda wrote:
Hi, I worried the difference between "tup_returned" and "tup_fetched" in pg_stat_database. I assumed that "tup_returned" means the number of tuples that returned to clients. Of course, this is wrong.
- Number of rows returned by queries in this database + Number of live rows returned by sequential scans of queries in this database - Number of rows fetched by queries in this database + Number of live rows fetched by index scan of queries in this database I found the following comments in pgstat.h. So maybe even these new descriptions are incorrect? * Note: for a table, tuples_returned is the number of tuples successfully * fetched by heap_getnext, while tuples_fetched is the number of tuples * successfully fetched by heap_fetch under the control of bitmap indexscans. * For an index, tuples_returned is the number of index entries returned by * the index AM, while tuples_fetched is the number of tuples successfully * fetched by heap_fetch under the control of simple indexscans for this index. Regards, -- Fujii Masao Advanced Computing Technology Center Research and Development Headquarters NTT DATA CORPORATION
