Sometimes the profileContent of ProfileElement is very large (more than 30MB), and this kind of huge string object may cause performance problems for gc. But we use them only when we invoke profile relevant restful apis (such as /profile/{format}/{query_id}, /api/profile and so on), so we need to lazy load them.
MetricRegistry::trigger_all_hooks holds the metrics lock and is stuck in get_je_metrics, to_prometheus is waiting for MetricRegistry::trigger_all_hooks to release the lock, so get_je_metrics is no longer called in MetricRegistry::trigger_all_hooks.
Support using this sql to refresh mtmv manually. It can generate a mtmv task right now.
```
REFRESH MATERIALIZED VIEW test_mv_view [complete];
```
You can use `show mtmv task` to show the latest task.
In this pr, I also try to clear the mtmv tasks when drop the mtmv to make sure test suite to be right
Add DATA_TYPE in information schema for types: datev2, datatimev2, decimal, jsonb. It was 'unknown' for these types and cause problem for tools such as BI using information schema.
support 4 phase Aggregation.
example:
`select count(distinct k1), sum(k2) from t`
suppose t.k0 is distribute key.
we have plan
```
Agg(DISTINCT_GLOBAL)
|
Exchange(Gather)
|
Agg(DISTINCT_LOCAL)
|
Agg(GLOBAL)
|
Exchange(hash distribute by k1)
|
Agg(LOCAL)
|
scan
```
limitations:
1. only support sql with one distinct.
not support:`select count(distinct k1), count(distinct k2) from t`
2. only support sql with distinct one column
not support: `select count(distinct k1, k2) from t`
In disk balancer, if a tablet is in highly concurrent load,
new rowset creation time(which use current time) may be same as the
newest rowset, and when add tablet, there has a creation time check
that new_time must bigger than old time, so disk balancer will failed
many times and makes this tablet lose many verisons as migration will
block writes.
Cached OlapScanNode each time call `addScanRangeLocations` will add TScanRangeLocations to result.
So `result` could grow too large and lead `getReplicaNumPerHost` a cpu hot spot in it's loop.
Doris always delays the execution of expressions as possible as it can, so as the expansion of constant expression. Given below SQL:
```sql
select i from (select 'abc' as i, sum(birth) as j from subquerytest2) as tmp
```
The aggregation would be eliminated, since its output is not required by the outer block, but the expasion for constant expression would be done in the final result expr, and since aggreagete output has been eliminate, the expasion would actually do nothing, and finally cause a empty results.
To fix this, we materialize the results expr in the inner block for such SQL, it may affect performance, but better than let system produce a mistaken result.
convert_nullable_flags does not contain nullable info for RowID column, but valid_column_ids contain RowID column, nullable falg will be undefined for RowID column
1.Compatible with the old optimizer, the sort and limit in the subquery will not take effect, just delete it directly.
```
select * from sub_query_correlated_subquery1 where sub_query_correlated_subquery1.k1 > (select sum(sub_query_correlated_subquery3.k3) a from sub_query_correlated_subquery3 where sub_query_correlated_subquery3.v2 = sub_query_correlated_subquery1.k2 order by a limit 1);
```
2.Adjust the unnesting position of the subquery to ensure that the conjunct in the filter has been optimized, and then unnesting
Support:
```
SELECT DISTINCT k1 FROM sub_query_correlated_subquery1 i1 WHERE ((SELECT count(*) FROM sub_query_correlated_subquery1 WHERE ((k1 = i1.k1) AND (k2 = 2)) or ((k1 = i1.k1) AND (k2 = 1)) ) > 0);
```
The reason why the above can be supported is that conjunction will be performed, which can be converted into the following
```
SELECT DISTINCT k1 FROM sub_query_correlated_subquery1 i1 WHERE ((SELECT count(*) FROM sub_query_correlated_subquery1 WHERE ((k1 = i1.k1) AND (k2 = 2 or k2 = 1)) ) > 0);
```
Not Support:
```
SELECT DISTINCT k1 FROM sub_query_correlated_subquery1 i1 WHERE ((SELECT count(*) FROM sub_query_correlated_subquery1 WHERE ((k1 = i1.k1) AND (k2 = 2)) or ((k2 = i1.k1) AND (k2 = 1)) ) > 0);
```
1. When mapping column from external datasource, use date/datetimev2 as default type
2. check `is_cancelled` when read data, to avoid endless loop after query is cancelled
