Hello Igor, I have pushed into 10.4-mdev16188 tree a patch that adds EXPLAIN FORMAT=JSON support. There is no ANALYZE support, yet. main.rowid_filter has an example of EXPLAIN FORMAT=JSON at the bottom. The filter is described like so: + "rowid_filter": { + "range": { + "key": "i_l_shipdate", + "used_key_parts": ["l_shipDATE"] + }, + "rows": 8, + "selectivity_pct": 0.1332 + }, Here "rows" is how many rows we will get from the quick select that is used to build the filter. selectivity_pct is the selectivity of the filter. You will also notice this change from (1%) to (0%): -1 SIMPLE lineitem range|filter PRIMARY,i_l_shipdate,i_l_receiptdate,i_l_orderkey,i_l_orderkey_quantity i_l_receiptdate|i_l_shipdate 4|4 NULL 6 (1%) Using index condition; Using where; Using filter +1 SIMPLE lineitem range|filter PRIMARY,i_l_shipdate,i_l_receiptdate,i_l_orderkey,i_l_orderkey_quantity i_l_receiptdate|i_l_shipdate 4|4 NULL 6 (0%) Using index condition; Using where; Using filter This is because the original code had a piece of logic in JOIN_TAB::save_filter_explain_data: print "1%" if it was "0%". I'm wondering, is there any reason we cannot print the number with greater precision in this case? BR Sergei -- Sergei Petrunia, Software Developer MariaDB Corporation | Skype: sergefp | Blog: http://s.petrunia.net/blog