Add string function split_part

be/src/exprs/string_functions.cpp

@@ -761,4 +761,61 @@ StringVal StringFunctions::money_format(FunctionContext *context, const LargeInt
     return do_money_format(context, ss.str());
 }
 
+static int indexOf(const uint8_t* source, int sourceOffset, int sourceCount,
+                const uint8_t* target, int targetOffset, int targetCount,
+                int fromIndex) {
+    if (fromIndex >= sourceCount) {
+        return (targetCount == 0 ? sourceCount : -1);
+    }
+    if (fromIndex < 0) {
+        fromIndex = 0;
+    }
+    if (targetCount == 0) {
+        return fromIndex;
+    }
+    const uint8_t first = target[targetOffset];
+    int max = sourceOffset + (sourceCount - targetCount);
+    for (int i = sourceOffset + fromIndex; i <= max; i++) {
+        if (source[i] != first) { // Look for first character
+            while (++i <= max && source[i] != first);
+        }
+        if (i <= max) { // Found first character, now look at the rest of v2
+            int j = i + 1;
+            int end = j + targetCount - 1;
+            for (int k = targetOffset + 1; j < end && source[j] == target[k]; j++, k++);
+            if (j == end) {
+                return i - sourceOffset; // Found whole string.
+            }
+        }
+    }
+    return -1;
+}
+
+
+StringVal StringFunctions::split_part(FunctionContext* context,const StringVal& content,
+                                      const StringVal& delimiter,const IntVal& field) {
+    if (field.val <= 0) return StringVal::null();
+    int find[field.val]; //store substring position
+    for(int i=0;i<=field.val;i++) find[i] = -1; // init
+    int from = 0;
+    for(int i=1;i<=field.val;i++){ // find
+        find[i-1] = indexOf(content.ptr,0,content.len, delimiter.ptr,0,delimiter.len,from);
+        from = find[i-1] + 1;
+        if (find[i-1] == -1) {
+            break;
+        }
+    }
+    if ((field.val>1 && find[field.val-2] == -1) || (field.val==1 && find[field.val-1] == -1)){ // not find
+        return StringVal::null();
+    }
+    int start_pos,len;
+    if (field.val == 1) { // find need split first part
+        start_pos = 0;
+    } else {
+        start_pos = find[field.val-2] + delimiter.len;
+    }
+    len = (find[field.val - 1] == -1 ? content.len : find[field.val-1]) - start_pos;
+    return StringVal(content.ptr + start_pos, len);
+}
+
 }

be/src/exprs/string_functions.h

@@ -174,6 +174,9 @@ class StringFunctions {
         ss << std::put_money(v);
         return AnyValUtil::from_string_temp(context, ss.str());
     };
+
+    static StringVal split_part(FunctionContext* context,const StringVal& content,
+                             const StringVal& delimiter,const IntVal& field);
 };
 }
 

be/test/exprs/string_functions_test.cpp

@@ -123,6 +123,35 @@ TEST_F(StringFunctionsTest, money_format_decimal_v2) {
     ASSERT_EQ(expected, result);
 }
 
+TEST_F(StringFunctionsTest, split_part) {
+    doris_udf::FunctionContext* context = new doris_udf::FunctionContext();
+    ASSERT_EQ(AnyValUtil::from_string_temp(context,std::string("hello")),
+            StringFunctions::split_part(context, StringVal("hello word"), StringVal(" "), 1));
+
+    ASSERT_EQ(AnyValUtil::from_string_temp(context,std::string("word")),
+            StringFunctions::split_part(context, StringVal("hello word"), StringVal(" "), 2));
+
+    ASSERT_EQ(StringVal::null(),
+            StringFunctions::split_part(context, StringVal("hello word"), StringVal(" "), 3));
+
+    ASSERT_EQ(AnyValUtil::from_string_temp(context,std::string("")),
+            StringFunctions::split_part(context, StringVal("hello word"), StringVal("hello"), 1));
+
+    ASSERT_EQ(AnyValUtil::from_string_temp(context,std::string(" word")),
+            StringFunctions::split_part(context, StringVal("hello word"), StringVal("hello"), 2));
+
+    ASSERT_EQ(AnyValUtil::from_string_temp(context,std::string("2019年9")),
+            StringFunctions::split_part(context, StringVal("2019年9月8日"), StringVal("月"), 1));
+        ASSERT_EQ(AnyValUtil::from_string_temp(context,std::string("")),
+                  StringFunctions::split_part(context, StringVal("abcdabda"), StringVal("a"), 1));
+        ASSERT_EQ(AnyValUtil::from_string_temp(context,std::string("bcd")),
+                  StringFunctions::split_part(context, StringVal("abcdabda"), StringVal("a"), 2));
+        ASSERT_EQ(AnyValUtil::from_string_temp(context,std::string("bd")),
+                  StringFunctions::split_part(context, StringVal("abcdabda"), StringVal("a"), 3));
+        ASSERT_EQ(AnyValUtil::from_string_temp(context,std::string("")),
+                  StringFunctions::split_part(context, StringVal("abcdabda"), StringVal("a"), 4));
+}
+
 }
 
 int main(int argc, char** argv) {

docs/documentation/cn/sql-reference/sql-functions/string-functions/split_part.md

@@ -0,0 +1,42 @@
+# split_part
+
+## Syntax
+
+`VARCHAR split_part(VARCHAR content, VARCHAR delimiter, INT field)`
+
+## Description
+
+根据分割符拆分字符串, 返回指定的分割部分(从一开始计数)。
+
+## Examples
+
+```
+mysql> select split_part("hello word", " ", 1);
++----------------------------------+
+| split_part('hello word', ' ', 1) |
++----------------------------------+
+| hello                            |
++----------------------------------+
+
+
+mysql> select split_part("hello word", " ", 2);
++----------------------------------+
+| split_part('hello word', ' ', 2) |
++----------------------------------+
+| word                             |
++----------------------------------+
+
+mysql> select split_part("2019年7月8号", "月", 1);
++-----------------------------------------+
+| split_part('2019年7月8号', '月', 1)     |
++-----------------------------------------+
+| 2019年7                                 |
++-----------------------------------------+
+
+mysql> select split_part("abca", "a", 1);
++----------------------------+
+| split_part('abca', 'a', 1) |
++----------------------------+
+|                            |
++----------------------------+
+```

gensrc/script/doris_builtins_functions.py

@@ -558,6 +558,8 @@
         '_ZN5doris15StringFunctions12money_formatEPN9doris_udf15FunctionContextERKNS1_10DecimalValE'],
     [['money_format'], 'VARCHAR', ['DECIMALV2'],
         '_ZN5doris15StringFunctions12money_formatEPN9doris_udf15FunctionContextERKNS1_12DecimalV2ValE'],
+    [['split_part'], 'VARCHAR', ['VARCHAR', 'VARCHAR', 'INT'],
+        '_ZN5doris15StringFunctions10split_partEPN9doris_udf15FunctionContextERKNS1_9StringValES6_RKNS1_6IntValE'],
 
     # Utility functions
     [['sleep'], 'BOOLEAN', ['INT'],