The explain of SQL output doesn't help

[killme2008]

What type of enhancement is this?

User experience

What does the enhancement do?

For example:

mysql> explain select * from test where i = 'hello2';
+---------------+--------------------------------------------------+
| plan_type     | plan                                             |
+---------------+--------------------------------------------------+
| logical_plan  | MergeScan [is_placeholder=false]                 |
| physical_plan | MergeScanExec: peers=[4415226380288(1028, 0), ]
 |
+---------------+--------------------------------------------------+

We just saw a MergeScan node, without any filter or table scan node etc. And we don't know what is_placeholder is in logical_plan or what peers means in physical_plan.

If we are using explain analyze, we don't get any info about whether the query uses the index or not:

mysql> explain analyze select * from test where i = 'hello2';
+-------------------+----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| plan_type         | plan                                                                                                                                                                             |
+-------------------+----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| Plan with Metrics | MergeScanExec: peers=[4415226380288(1028, 0), ], metrics=[output_rows=1, greptime_exec_cost=0, first_consume_time=25.720291ms, finish_time=25.839667ms, ready_time=24.626125ms]
 |
+-------------------+----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+

I am uncertain whether it's intentional or simply another glitch.

Implementation challenges

No response