MDEV-18741: Optimizer trace: multi-part key ranges are printed incorrectly

Changed the function append_range_all_keyparts to use sel_arg_range_seq_init / sel_arg_range_seq_next to produce ranges.
Also adjusted to print format for the ranges, now the ranges are printed as:
    (keypart1_min, keypart2_min,..)  OP (keypart1_name,keypart2_name, ..) OP (keypart1_max,keypart2_max, ..)

Also added more tests for range and index merge access for optimizer trace

mysql-test/main/opt_trace.test

@@ -387,4 +387,61 @@ SELECT COUNT(*) FROM v1 WHERE MATCH (f) AGAINST ('fooba');
 DROP VIEW v1;
 DROP TABLE t1;
 
+--echo #
+--echo # MDEV-18741: Optimizer trace: multi-part key ranges are printed incorrectly.
+--echo #
+
+create table t0(a int);
+insert into t0 values (0),(1),(2),(3),(4),(5),(6),(7),(8),(9);
+create table one_k (a int);
+insert into one_k select A.a + B.a*10 + C.a*100 from t0 A, t0 B, t0 C;
+create table t1 ( a int, b int, key a_b(a,b));
+insert into t1 select a,a from one_k;
+set optimizer_trace='enabled=on';
+
+explain select * from t1 force index (a_b) where a=2 and b=4;
+select JSON_DETAILED(JSON_EXTRACT(trace, '$**.analyzing_range_alternatives')) from INFORMATION_SCHEMA.OPTIMIZER_TRACE;
+
+explain select * from t1 where a >= 900 and b between 10 and 20;
+select JSON_DETAILED(JSON_EXTRACT(trace, '$**.analyzing_range_alternatives')) from INFORMATION_SCHEMA.OPTIMIZER_TRACE;
+
+drop table t0,t1;
+
+create table t1 (start_date date, end_date date, filler char(100), key(start_date, end_date)) ;
+--disable_warnings
+insert into t1 select date_add(now(), interval a day), date_add(now(), interval (a+7) day), 'data' from one_k;
+--enable_warnings
+explain select * from t1 force index(start_date) where start_date >= '2019-02-10' and end_date <'2019-04-01';
+select JSON_DETAILED(JSON_EXTRACT(trace, '$**.analyzing_range_alternatives')) from INFORMATION_SCHEMA.OPTIMIZER_TRACE;
+drop table t1,one_k;
+
+create table ten(a int);
+insert into ten values (0),(1),(2),(3),(4),(5),(6),(7),(8),(9);
+create table t1 (
+  a int not null,
+  b int not null,
+  c int not null,
+  d int not null,
+  key a_b_c(a,b,c)
+);
+
+insert into t1 select a,a, a,a from ten;
+explain select * from t1 force index(a_b_c) where a between 1 and 4 and b < 50;
+select JSON_DETAILED(JSON_EXTRACT(trace, '$**.analyzing_range_alternatives')) from INFORMATION_SCHEMA.OPTIMIZER_TRACE;
+drop table ten,t1;
+
+--echo # Ported test from MYSQL for ranges involving Binary column
+
+CREATE TABLE t1(i INT PRIMARY KEY, b BINARY(16), INDEX i_b(b));
+INSERT INTO t1 VALUES (1, x'D95B94336A9946A39CF5B58CFE772D8C');
+INSERT INTO t1 VALUES (2, NULL);
+
+EXPLAIN SELECT * FROM t1 WHERE b IN (0xD95B94336A9946A39CF5B58CFE772D8C);
+select JSON_DETAILED(JSON_EXTRACT(trace, '$**.analyzing_range_alternatives')) from INFORMATION_SCHEMA.OPTIMIZER_TRACE;
+
+EXPLAIN SELECT * FROM t1 WHERE b IS NULL;
+select JSON_DETAILED(JSON_EXTRACT(trace, '$**.analyzing_range_alternatives')) from INFORMATION_SCHEMA.OPTIMIZER_TRACE;
+
+drop table t1;
+
 set optimizer_trace='enabled=off';

mysql-test/main/opt_trace_index_merge.test

@@ -19,3 +19,115 @@ select * from information_schema.OPTIMIZER_TRACE;
 drop table t0,t1;
 set optimizer_trace="enabled=off";
 set @@optimizer_switch= @tmp_opt_switch;
+
+--echo # More tests added index_merge access
+
+--enable_warnings
+create table t1
+(
+  /* Field names reflect value(rowid) distribution, st=STairs, swt= SaWTooth */
+  st_a int not null default 0,
+  swt1a int not null default 0,
+  swt2a int not null default 0,
+
+  st_b int not null default 0,
+  swt1b int not null default 0,
+  swt2b int not null default 0,
+
+  /* fields/keys for row retrieval tests */
+  key1 int,
+  key2 int,
+  key3 int,
+  key4 int,
+
+  /* make rows much bigger then keys */
+  filler1 char (200),
+  filler2 char (200),
+  filler3 char (200),
+  filler4 char (200),
+  filler5 char (200),
+  filler6 char (200),
+
+  /* order of keys is important */
+  key sta_swt12a(st_a,swt1a,swt2a),
+  key sta_swt1a(st_a,swt1a),
+  key sta_swt2a(st_a,swt2a),
+  key sta_swt21a(st_a,swt2a,swt1a),
+  key st_a(st_a),
+  key stb_swt1a_2b(st_b,swt1b,swt2a),
+  key stb_swt1b(st_b,swt1b),
+  key st_b(st_b),
+
+  key(key1),
+  key(key2),
+  key(key3),
+  key(key4)
+) ;
+# Fill table
+create table t0 as select * from t1;
+--disable_query_log
+--echo # Printing of many insert into t0 values (....) disabled.
+let $cnt=1000;
+while ($cnt)
+{ 
+  eval insert into t0 values (1, 2, 3, 1, 2, 3, 0, 0, 0, 0, 'data1', 'data2', 'data3', 'data4', 'data5', 'data6');
+  dec $cnt;
+}
+--enable_query_log
+
+alter table t1 disable keys;
+--disable_query_log
+--echo # Printing of many insert into t1 select .... from t0 disabled.
+let $1=4;
+while ($1)
+{ 
+  let $2=4;
+  while ($2)
+  { 
+    let $3=4;
+    while ($3)
+    {
+      eval insert into t1 select $1, $2, $3, $1 ,$2, $3, key1, key2, key3, key4, filler1, filler2, filler3, filler4, filler5, filler6 from t0;
+      dec $3;
+    }
+    dec $2;
+  }
+ dec $1;
+}
+
+--echo # Printing of many insert into t1 (...) values (....) disabled.
+# Row retrieval tests
+# -1 is used for values 'out of any range we are using'
+# insert enough rows for index intersection to be used for (key1,key2)
+insert into t1 (key1, key2, key3, key4, filler1) values (100, 100, 100, 100,'key1-key2-key3-key4');
+let $cnt=400;
+while ($cnt)
+{
+  eval insert into t1 (key1, key2, key3, key4, filler1) values (100, -1, 100, -1,'key1-key3');
+  dec $cnt;
+}
+let $cnt=400;
+while ($cnt)
+{
+  eval insert into t1 (key1, key2, key3, key4, filler1) values (-1, 100, -1, 100,'key2-key4');
+  dec $cnt;
+}
+--enable_query_log
+alter table t1 enable keys;
+
+insert into t1 (key1, key2, key3, key4, filler1) values (100, 100, -1, -1, 'key1-key2');
+insert into t1 (key1, key2, key3, key4, filler1) values (-1, -1, 100, 100, 'key4-key3');
+set optimizer_trace='enabled=on';
+
+--echo #  3-way ROR-intersection
+explain select key1,key2,key3 from t1 where key1=100 and key2=100 and key3=100;
+select JSON_DETAILED(JSON_EXTRACT(trace, '$**.analyzing_range_alternatives')) from INFORMATION_SCHEMA.OPTIMIZER_TRACE;
+select JSON_DETAILED(JSON_EXTRACT(trace, '$**.chosen_range_access_summary')) from INFORMATION_SCHEMA.OPTIMIZER_TRACE;
+
+--echo # ROR-union(ROR-intersection, ROR-range)
+explain select key1,key2,key3,key4 from t1 where key1=100 and key2=100 or key3=100 and key4=100;
+select JSON_DETAILED(JSON_EXTRACT(trace, '$**.analyzing_range_alternatives')) from INFORMATION_SCHEMA.OPTIMIZER_TRACE;
+select JSON_DETAILED(JSON_EXTRACT(trace, '$**.chosen_range_access_summary')) from INFORMATION_SCHEMA.OPTIMIZER_TRACE;
+
+drop table t0,t1;
+set optimizer_trace="enabled=off";

mysql-test/main/opt_trace_index_merge_innodb.result

@@ -116,7 +116,7 @@ explain select * from t1 where pk1 != 0  and key1 = 1	{
                     "range_scan_alternatives": [
                       {
                         "index": "PRIMARY",
-                        "ranges": ["pk1 < 0", "0 < pk1"],
+                        "ranges": ["(pk1) < (0)", "(0) < (pk1)"],
                         "rowid_ordered": true,
                         "using_mrr": false,
                         "index_only": false,
@@ -127,7 +127,7 @@ explain select * from t1 where pk1 != 0  and key1 = 1	{
                       },
                       {
                         "index": "key1",
-                        "ranges": ["1 <= key1 <= 1"],
+                        "ranges": ["(1) <= (key1) <= (1)"],
                         "rowid_ordered": true,
                         "using_mrr": false,
                         "index_only": false,
@@ -164,7 +164,7 @@ explain select * from t1 where pk1 != 0  and key1 = 1	{
                       "type": "range_scan",
                       "index": "key1",
                       "rows": 1,
-                      "ranges": ["1 <= key1 <= 1"]
+                      "ranges": ["(1) <= (key1) <= (1)"]
                     },
                     "rows_for_plan": 1,
                     "cost_for_plan": 2.3751,

sql/opt_range.h

@@ -458,7 +458,9 @@ class SEL_ARG :public Sql_alloc
     SEL_ARG *key_tree= first();
     uint res= key_tree->store_min(key[key_tree->part].store_length,
                                   range_key, *range_key_flag);
-    *range_key_flag|= key_tree->min_flag;
+    // add flags only if a key_part is written to the buffer
+    if (res)
+      *range_key_flag|= key_tree->min_flag;
     if (key_tree->next_key_part &&
 	key_tree->next_key_part->type == SEL_ARG::KEY_RANGE &&
         key_tree->part != last_part &&
@@ -480,7 +482,8 @@ class SEL_ARG :public Sql_alloc
     SEL_ARG *key_tree= last();
     uint res=key_tree->store_max(key[key_tree->part].store_length,
                                  range_key, *range_key_flag);
-    (*range_key_flag)|= key_tree->max_flag;
+    if (res)
+      (*range_key_flag)|= key_tree->max_flag;
     if (key_tree->next_key_part &&
 	key_tree->next_key_part->type == SEL_ARG::KEY_RANGE &&
         key_tree->part != last_part &&

sql/opt_range_mrr.cc

@@ -53,6 +53,11 @@ typedef struct st_sel_arg_range_seq
   int i; /* Index of last used element in the above array */
   
   bool at_start; /* TRUE <=> The traversal has just started */
+  /*
+    Iteration functions will set this to FALSE
+    if ranges being traversed do not allow to construct a ROR-scan"
+  */
+  bool is_ror_scan;
 } SEL_ARG_RANGE_SEQ;
 
 
@@ -165,7 +170,7 @@ bool sel_arg_range_seq_next(range_seq_t rseq, KEY_MULTI_RANGE *range)
     seq->i--;
     step_down_to(seq, key_tree->next);
     key_tree= key_tree->next;
-    seq->param->is_ror_scan= FALSE;
+    seq->is_ror_scan= FALSE;
     goto walk_right_n_up;
   }
 
@@ -207,7 +212,7 @@ bool sel_arg_range_seq_next(range_seq_t rseq, KEY_MULTI_RANGE *range)
             !memcmp(cur[-1].min_key, cur[-1].max_key, len) &&
             !key_tree->min_flag && !key_tree->max_flag))
       {
-        seq->param->is_ror_scan= FALSE;
+        seq->is_ror_scan= FALSE;
         if (!key_tree->min_flag)
           cur->min_key_parts += 
             key_tree->next_key_part->store_min_key(seq->param->key[seq->keyno],
@@ -312,7 +317,7 @@ bool sel_arg_range_seq_next(range_seq_t rseq, KEY_MULTI_RANGE *range)
         range->range_flag |= UNIQUE_RANGE | (cur->min_key_flag & NULL_RANGE);
     }
       
-    if (seq->param->is_ror_scan)
+    if (seq->is_ror_scan)
     {
       /*
         If we get here, the condition on the key was converted to form
@@ -327,7 +332,7 @@ bool sel_arg_range_seq_next(range_seq_t rseq, KEY_MULTI_RANGE *range)
             (range->start_key.length == range->end_key.length) &&
             !memcmp(range->start_key.key, range->end_key.key, range->start_key.length) &&
             is_key_scan_ror(seq->param, seq->real_keyno, key_tree->part + 1)))
-        seq->param->is_ror_scan= FALSE;
+        seq->is_ror_scan= FALSE;
     }
   }
   seq->param->range_count++;