improve performent of hash join when build table has to many duplicated rows, this will cause hash table collisions and slow down the probe performence.
In this pr when join type is semi join or anti join, we will build a hash table without duplicated rows.
benchmark:
dataset: tpcds dataset `store_sales` and `catalog_sales`
```
mysql> select count(*) from catalog_sales;
+----------+
| count(*) |
+----------+
| 14401261 |
+----------+
1 row in set (0.44 sec)
mysql> select count(distinct cs_bill_cdemo_sk) from catalog_sales;
+------------------------------------+
| count(DISTINCT `cs_bill_cdemo_sk`) |
+------------------------------------+
| 1085080 |
+------------------------------------+
1 row in set (2.46 sec)
mysql> select count(*) from store_sales;
+----------+
| count(*) |
+----------+
| 28800991 |
+----------+
1 row in set (0.84 sec)
mysql> select count(distinct ss_addr_sk) from store_sales;
+------------------------------+
| count(DISTINCT `ss_addr_sk`) |
+------------------------------+
| 249978 |
+------------------------------+
1 row in set (2.57 sec)
```
test querys:
query1: `select count(*) from (select store_sales.ss_addr_sk from store_sales left semi join catalog_sales on catalog_sales.cs_bill_cdemo_sk = store_sales.ss_addr_sk) a;`
query2: `select count(*) from (select catalog_sales.cs_bill_cdemo_sk from catalog_sales left semi join store_sales on catalog_sales.cs_bill_cdemo_sk = store_sales.ss_addr_sk) a;`
benchmark result:
||query1|query2|
|:--:|:--:|:--:|
|before|14.76 sec|3 min 16.52 sec|
|after|12.64 sec|10.34 sec|
Remove unused LLVM related codes of directory:be/src/exec (#2910)
there are many LLVM related codes in code base, but these codes are not really used.
The higher version of GCC is not compatible with the LLVM 3.4.2 version currently used by Doris.
The PR delete all LLVM related code of directory: be/src/exec.
* Change Null-safe equal operator from cross join to hash join
ISSUE-2136
This commit change the join method from cross join to hash join when the equal operator is Null-safe '<=>'.
It will improve the speed of query which has the Null-safe equal operator.
The finds_nulls field is used to save if there is Null-safe operator.
The finds_nulls[i] is true means that the i-th equal operator is Null-safe.
The equal function in hash table will return true, if both val and loc are NULL when finds_nulls[i] is true.
