# select count(*) from information_schema.tikv_region_peers;
+----------+
| count(*) |
+----------+
|   700476 |
+----------+
new: 1 row in set (10.30 sec)
old: 1 row in set (10.29 sec)
# almost cost the same time when fetch all regionsInfo

# select * from tikv_region_peers where region_id=395005;
+-----------+---------+----------+------------+-----------+--------+--------------+
| REGION_ID | PEER_ID | STORE_ID | IS_LEARNER | IS_LEADER | STATUS | DOWN_SECONDS |
+-----------+---------+----------+------------+-----------+--------+--------------+
|    395005 |  410054 |        4 |          0 |         1 | NORMAL |         NULL |
+-----------+---------+----------+------------+-----------+--------+--------------+
new: 1 row in set (0.00 sec)
old: 1 row in set (11.37 sec)
# faster when specify one region_id

# select * from tikv_region_peers where region_id in (395005,395015,395017);
+-----------+---------+----------+------------+-----------+--------+--------------+
| REGION_ID | PEER_ID | STORE_ID | IS_LEARNER | IS_LEADER | STATUS | DOWN_SECONDS |
+-----------+---------+----------+------------+-----------+--------+--------------+
|    395005 |  410054 |        4 |          0 |         1 | NORMAL |         NULL |
|    395015 |  410061 |        4 |          0 |         1 | NORMAL |         NULL |
|    395017 |  759007 |        1 |          0 |         1 | NORMAL |         NULL |
+-----------+---------+----------+------------+-----------+--------+--------------+
new: 3 rows in set (0.00 sec)
old: 3 rows in set (10.10 sec)
# faster when specify three region_id

# select count(*) from tikv_region_peers where store_id=4;
+----------+
| count(*) |
+----------+
|   182409 |
+----------+
new: 1 row in set (5.45 sec)
old: 1 row in set (10.38 sec)
# faster when specify one store_id

# select count(*) from tikv_region_peers where region_id=395005 and store_id=4;
+----------+
| count(*) |
+----------+
|        1 |
+----------+
new: 1 row in set (4.80 sec)
old: 1 row in set (11.03 sec)
# faster when specify one store_id

# select * from tikv_region_peers where region_id in (395005,395015,395017) and store_id=4;
+-----------+---------+----------+------------+-----------+--------+--------------+
| REGION_ID | PEER_ID | STORE_ID | IS_LEARNER | IS_LEADER | STATUS | DOWN_SECONDS |
+-----------+---------+----------+------------+-----------+--------+--------------+
|    395005 |  410054 |        4 |          0 |         1 | NORMAL |         NULL |
|    395015 |  410061 |        4 |          0 |         1 | NORMAL |         NULL |
+-----------+---------+----------+------------+-----------+--------+--------------+
new: 2 rows in set (4.88 sec)
old: 2 rows in set (10.69 sec)
# faster when specify one store_id

# select * from tikv_region_peers where region_id in (395005,395015,395017) and store_id=0;
Empty set (0.01 sec)
Empty set (10.83 sec)
# faster when specify one store_id

# select count(*) from tikv_region_peers where store_id in (4,7);
+----------+
| count(*) |
+----------+
|   364012 |
+----------+
1 row in set (9.32 sec)
1 row in set (10.30 sec)
# closer when specify two store_id

# select * from tikv_region_peers where region_id in (395005,395015,395017) and store_id in (1,4);
+-----------+---------+----------+------------+-----------+--------+--------------+
| REGION_ID | PEER_ID | STORE_ID | IS_LEARNER | IS_LEADER | STATUS | DOWN_SECONDS |
+-----------+---------+----------+------------+-----------+--------+--------------+
|    395005 |  410054 |        4 |          0 |         1 | NORMAL |         NULL |
|    395015 |  410061 |        4 |          0 |         1 | NORMAL |         NULL |
|    395017 |  759007 |        1 |          0 |         1 | NORMAL |         NULL |
+-----------+---------+----------+------------+-----------+--------+--------------+
new: 3 rows in set (12.90 sec)
old: 3 rows in set (12.03 sec)
# slower when specify two or more store_id