InnoDB results in my env: $./bug43968.sh Table Non_unique Key_name Seq_in_index Column_name Collation Cardinality Sub_part Packed Null Index_type Comment TEST_LOG 0 PRIMARY 1 SEQ A 50 NULL NULL BTREE TEST_LOG 0 PRIMARY 2 TEST_ID A 50 NULL NULL BTREE TEST_LOG 1 IX_TEST_ID 1 TEST_ID A 50 NULL NULL BTREE real 0m0.372s user 0m0.006s sys 0m0.007s Table Non_unique Key_name Seq_in_index Column_name Collation Cardinality Sub_part Packed Null Index_type Comment TEST_LOG 0 PRIMARY 1 SEQ A 114898 NULL NULL BTREE TEST_LOG 0 PRIMARY 2 TEST_ID A 114898 NULL NULL BTREE TEST_LOG 1 IX_TEST_ID 1 TEST_ID A 114898 NULL NULL BTREE real 0m0.355s user 0m0.007s sys 0m0.009s Table Non_unique Key_name Seq_in_index Column_name Collation Cardinality Sub_part Packed Null Index_type Comment TEST_LOG 0 PRIMARY 1 SEQ A 216909 NULL NULL BTREE TEST_LOG 0 PRIMARY 2 TEST_ID A 216909 NULL NULL BTREE TEST_LOG 1 IX_TEST_ID 1 TEST_ID A 216909 NULL NULL BTREE real 0m0.548s user 0m0.006s sys 0m0.009s Table Non_unique Key_name Seq_in_index Column_name Collation Cardinality Sub_part Packed Null Index_type Comment TEST_LOG 0 PRIMARY 1 SEQ A 332303 NULL NULL BTREE TEST_LOG 0 PRIMARY 2 TEST_ID A 332303 NULL NULL BTREE TEST_LOG 1 IX_TEST_ID 1 TEST_ID A 332303 NULL NULL BTREE real 0m0.248s user 0m0.007s sys 0m0.009s Table Non_unique Key_name Seq_in_index Column_name Collation Cardinality Sub_part Packed Null Index_type Comment TEST_LOG 0 PRIMARY 1 SEQ A 443298 NULL NULL BTREE TEST_LOG 0 PRIMARY 2 TEST_ID A 443298 NULL NULL BTREE TEST_LOG 1 IX_TEST_ID 1 TEST_ID A 443298 NULL NULL BTREE real 0m0.518s user 0m0.006s sys 0m0.007s Table Non_unique Key_name Seq_in_index Column_name Collation Cardinality Sub_part Packed Null Index_type Comment TEST_LOG 0 PRIMARY 1 SEQ A 554381 NULL NULL BTREE TEST_LOG 0 PRIMARY 2 TEST_ID A 554381 NULL NULL BTREE TEST_LOG 1 IX_TEST_ID 1 TEST_ID A 554381 NULL NULL BTREE real 0m1.275s user 0m0.008s sys 0m0.008s Table Non_unique Key_name Seq_in_index Column_name Collation Cardinality Sub_part Packed Null Index_type Comment TEST_LOG 0 PRIMARY 1 SEQ A 661764 NULL NULL BTREE TEST_LOG 0 PRIMARY 2 TEST_ID A 661764 NULL NULL BTREE TEST_LOG 1 IX_TEST_ID 1 TEST_ID A 661764 NULL NULL BTREE real 0m1.814s user 0m0.008s sys 0m0.008s Table Non_unique Key_name Seq_in_index Column_name Collation Cardinality Sub_part Packed Null Index_type Comment TEST_LOG 0 PRIMARY 1 SEQ A 772502 NULL NULL BTREE TEST_LOG 0 PRIMARY 2 TEST_ID A 772502 NULL NULL BTREE TEST_LOG 1 IX_TEST_ID 1 TEST_ID A 772502 NULL NULL BTREE real 0m1.512s user 0m0.006s sys 0m0.007s Table Non_unique Key_name Seq_in_index Column_name Collation Cardinality Sub_part Packed Null Index_type Comment TEST_LOG 0 PRIMARY 1 SEQ A 878408 NULL NULL BTREE TEST_LOG 0 PRIMARY 2 TEST_ID A 878408 NULL NULL BTREE TEST_LOG 1 IX_TEST_ID 1 TEST_ID A 878408 NULL NULL BTREE real 0m2.100s user 0m0.011s sys 0m0.012s Table Non_unique Key_name Seq_in_index Column_name Collation Cardinality Sub_part Packed Null Index_type Comment TEST_LOG 0 PRIMARY 1 SEQ A 989142 NULL NULL BTREE TEST_LOG 0 PRIMARY 2 TEST_ID A 989142 NULL NULL BTREE TEST_LOG 1 IX_TEST_ID 1 TEST_ID A 989142 NULL NULL BTREE real 0m2.189s user 0m0.008s sys 0m0.009s Table Non_unique Key_name Seq_in_index Column_name Collation Cardinality Sub_part Packed Null Index_type Comment TEST_LOG 0 PRIMARY 1 SEQ A 1100312 NULL NULL BTREE TEST_LOG 0 PRIMARY 2 TEST_ID A 1100312 NULL NULL BTREE TEST_LOG 1 IX_TEST_ID 1 TEST_ID A 1100312 NULL NULL BTREE real 0m2.944s user 0m0.007s sys 0m0.008s Table Non_unique Key_name Seq_in_index Column_name Collation Cardinality Sub_part Packed Null Index_type Comment TEST_LOG 0 PRIMARY 1 SEQ A 1210711 NULL NULL BTREE TEST_LOG 0 PRIMARY 2 TEST_ID A 1210711 NULL NULL BTREE TEST_LOG 1 IX_TEST_ID 1 TEST_ID A 1210711 NULL NULL BTREE real 0m13.747s user 0m0.011s sys 0m0.012s Table Non_unique Key_name Seq_in_index Column_name Collation Cardinality Sub_part Packed Null Index_type Comment TEST_LOG 0 PRIMARY 1 SEQ A 1313623 NULL NULL BTREE TEST_LOG 0 PRIMARY 2 TEST_ID A 1313623 NULL NULL BTREE TEST_LOG 1 IX_TEST_ID 1 TEST_ID A 1313623 NULL NULL BTREE real 0m10.627s user 0m0.007s sys 0m0.008s Table Non_unique Key_name Seq_in_index Column_name Collation Cardinality Sub_part Packed Null Index_type Comment TEST_LOG 0 PRIMARY 1 SEQ A 1361558 NULL NULL BTREE TEST_LOG 0 PRIMARY 2 TEST_ID A 1361558 NULL NULL BTREE TEST_LOG 1 IX_TEST_ID 1 TEST_ID A 1361558 NULL NULL BTREE real 0m11.316s user 0m0.007s sys 0m0.008s Terminated MyISAM results in my env: $./bug43968.sh Table Non_unique Key_name Seq_in_index Column_name Collation Cardinality Sub_part Packed Null Index_type Comment TEST_LOG 0 PRIMARY 1 SEQ A NULL NULL NULL BTREE TEST_LOG 0 PRIMARY 2 TEST_ID A 0 NULL NULL BTREE TEST_LOG 1 IX_TEST_ID 1 TEST_ID A NULL NULL NULL BTREE real 0m0.143s user 0m0.008s sys 0m0.009s Table Non_unique Key_name Seq_in_index Column_name Collation Cardinality Sub_part Packed Null Index_type Comment TEST_LOG 0 PRIMARY 1 SEQ A NULL NULL NULL BTREE TEST_LOG 0 PRIMARY 2 TEST_ID A 110000 NULL NULL BTREE TEST_LOG 1 IX_TEST_ID 1 TEST_ID A 110000 NULL NULL BTREE real 0m0.302s user 0m0.006s sys 0m0.008s Table Non_unique Key_name Seq_in_index Column_name Collation Cardinality Sub_part Packed Null Index_type Comment TEST_LOG 0 PRIMARY 1 SEQ A NULL NULL NULL BTREE TEST_LOG 0 PRIMARY 2 TEST_ID A 220000 NULL NULL BTREE TEST_LOG 1 IX_TEST_ID 1 TEST_ID A 220000 NULL NULL BTREE real 0m0.059s user 0m0.006s sys 0m0.007s Table Non_unique Key_name Seq_in_index Column_name Collation Cardinality Sub_part Packed Null Index_type Comment TEST_LOG 0 PRIMARY 1 SEQ A NULL NULL NULL BTREE TEST_LOG 0 PRIMARY 2 TEST_ID A 330000 NULL NULL BTREE TEST_LOG 1 IX_TEST_ID 1 TEST_ID A 330000 NULL NULL BTREE real 0m0.023s user 0m0.007s sys 0m0.008s Table Non_unique Key_name Seq_in_index Column_name Collation Cardinality Sub_part Packed Null Index_type Comment TEST_LOG 0 PRIMARY 1 SEQ A NULL NULL NULL BTREE TEST_LOG 0 PRIMARY 2 TEST_ID A 440000 NULL NULL BTREE TEST_LOG 1 IX_TEST_ID 1 TEST_ID A 440000 NULL NULL BTREE real 0m0.049s user 0m0.008s sys 0m0.010s Table Non_unique Key_name Seq_in_index Column_name Collation Cardinality Sub_part Packed Null Index_type Comment TEST_LOG 0 PRIMARY 1 SEQ A NULL NULL NULL BTREE TEST_LOG 0 PRIMARY 2 TEST_ID A 550000 NULL NULL BTREE TEST_LOG 1 IX_TEST_ID 1 TEST_ID A 550000 NULL NULL BTREE real 0m0.022s user 0m0.006s sys 0m0.008s Table Non_unique Key_name Seq_in_index Column_name Collation Cardinality Sub_part Packed Null Index_type Comment TEST_LOG 0 PRIMARY 1 SEQ A NULL NULL NULL BTREE TEST_LOG 0 PRIMARY 2 TEST_ID A 660000 NULL NULL BTREE TEST_LOG 1 IX_TEST_ID 1 TEST_ID A 660000 NULL NULL BTREE real 0m0.030s user 0m0.007s sys 0m0.008s Table Non_unique Key_name Seq_in_index Column_name Collation Cardinality Sub_part Packed Null Index_type Comment TEST_LOG 0 PRIMARY 1 SEQ A NULL NULL NULL BTREE TEST_LOG 0 PRIMARY 2 TEST_ID A 770000 NULL NULL BTREE TEST_LOG 1 IX_TEST_ID 1 TEST_ID A 770000 NULL NULL BTREE real 0m0.029s user 0m0.008s sys 0m0.008s Table Non_unique Key_name Seq_in_index Column_name Collation Cardinality Sub_part Packed Null Index_type Comment TEST_LOG 0 PRIMARY 1 SEQ A NULL NULL NULL BTREE TEST_LOG 0 PRIMARY 2 TEST_ID A 880000 NULL NULL BTREE TEST_LOG 1 IX_TEST_ID 1 TEST_ID A 880000 NULL NULL BTREE real 0m0.026s user 0m0.006s sys 0m0.008s Table Non_unique Key_name Seq_in_index Column_name Collation Cardinality Sub_part Packed Null Index_type Comment TEST_LOG 0 PRIMARY 1 SEQ A NULL NULL NULL BTREE TEST_LOG 0 PRIMARY 2 TEST_ID A 990000 NULL NULL BTREE TEST_LOG 1 IX_TEST_ID 1 TEST_ID A 990000 NULL NULL BTREE real 0m0.842s user 0m0.006s sys 0m0.008s Table Non_unique Key_name Seq_in_index Column_name Collation Cardinality Sub_part Packed Null Index_type Comment TEST_LOG 0 PRIMARY 1 SEQ A NULL NULL NULL BTREE TEST_LOG 0 PRIMARY 2 TEST_ID A 1100000 NULL NULL BTREE TEST_LOG 1 IX_TEST_ID 1 TEST_ID A 1100000 NULL NULL BTREE real 0m2.823s user 0m0.006s sys 0m0.007s Table Non_unique Key_name Seq_in_index Column_name Collation Cardinality Sub_part Packed Null Index_type Comment TEST_LOG 0 PRIMARY 1 SEQ A NULL NULL NULL BTREE TEST_LOG 0 PRIMARY 2 TEST_ID A 1210000 NULL NULL BTREE TEST_LOG 1 IX_TEST_ID 1 TEST_ID A 1210000 NULL NULL BTREE real 0m0.027s user 0m0.006s sys 0m0.007s Table Non_unique Key_name Seq_in_index Column_name Collation Cardinality Sub_part Packed Null Index_type Comment TEST_LOG 0 PRIMARY 1 SEQ A NULL NULL NULL BTREE TEST_LOG 0 PRIMARY 2 TEST_ID A 1320000 NULL NULL BTREE TEST_LOG 1 IX_TEST_ID 1 TEST_ID A 1320000 NULL NULL BTREE real 0m0.028s user 0m0.006s sys 0m0.008s Table Non_unique Key_name Seq_in_index Column_name Collation Cardinality Sub_part Packed Null Index_type Comment TEST_LOG 0 PRIMARY 1 SEQ A NULL NULL NULL BTREE TEST_LOG 0 PRIMARY 2 TEST_ID A 1430000 NULL NULL BTREE TEST_LOG 1 IX_TEST_ID 1 TEST_ID A 1430000 NULL NULL BTREE real 0m0.028s user 0m0.006s sys 0m0.008s Table Non_unique Key_name Seq_in_index Column_name Collation Cardinality Sub_part Packed Null Index_type Comment TEST_LOG 0 PRIMARY 1 SEQ A NULL NULL NULL BTREE TEST_LOG 0 PRIMARY 2 TEST_ID A 1540000 NULL NULL BTREE TEST_LOG 1 IX_TEST_ID 1 TEST_ID A 1540000 NULL NULL BTREE real 0m0.028s user 0m0.009s sys 0m0.009s Table Non_unique Key_name Seq_in_index Column_name Collation Cardinality Sub_part Packed Null Index_type Comment TEST_LOG 0 PRIMARY 1 SEQ A NULL NULL NULL BTREE TEST_LOG 0 PRIMARY 2 TEST_ID A 1650000 NULL NULL BTREE TEST_LOG 1 IX_TEST_ID 1 TEST_ID A 1650000 NULL NULL BTREE real 0m0.036s user 0m0.006s sys 0m0.008s Table Non_unique Key_name Seq_in_index Column_name Collation Cardinality Sub_part Packed Null Index_type Comment TEST_LOG 0 PRIMARY 1 SEQ A NULL NULL NULL BTREE TEST_LOG 0 PRIMARY 2 TEST_ID A 1750000 NULL NULL BTREE TEST_LOG 1 IX_TEST_ID 1 TEST_ID A 1750000 NULL NULL BTREE real 0m0.019s user 0m0.006s sys 0m0.007s Terminated Having or not partitions affects only # of milliseconds, but not degree.