adding docs for 128 bit xxhash

docs/sql-manual/sql-functions/scalar-functions/encrypt-digest-functions/xxhash-128.md

@@ -0,0 +1,69 @@
+---
+{
+    "title": "XXHASH_128",
+    "language": "en",
+    "description": "Calculate the 128-bit xxhash value of the input string or binary."
+}
+---
+
+## Description
+
+Calculate the 128-bit xxhash value of the input string or binary.
+
+## Syntax
+
+```sql
+XXHASH_128( <input> [ , <input> ... ] )
+```
+
+## Parameters
+
+| parameter | description      |
+|-----------|------------------|
+| `<input>`   | The 128-bit xxhash value to be calculated, accept string and binary types |
+
+## Return Value
+
+Returns the 128-bit xxhash value of the input string.
+
+## Examples
+
+```sql
+select xxhash_128(NULL), xxhash_128("hello"), xxhash_128("hello", "world");
+```
+
+```text
++------------------+-----------------------------------------+----------------------------------------+
+| xxhash_128(NULL) | xxhash_128("hello")                     | xxhash_128("hello", "world")           |
++------------------+-----------------------------------------+----------------------------------------+
+| NULL             | -98478366302105124680504504609445627880 | -9508340982777299797928774324431085410 |
++------------------+-----------------------------------------+----------------------------------------+
+```
+
+```sql
+-- vb (VarBinary) and vc (VarChar) used the same string during insertion.
+SELECT * FROM mysql_catalog.binary_test.binary_test;
+```
+```text
++------+------------+------+
+| id   | vb         | vc   |
++------+------------+------+
+|    1 | 0x616263   | abc  |
+|    2 | 0x78797A   | xyz  |
+|    3 | NULL       | NULL |
++------+------------+------+
+```
+
+```sql
+SELECT XXHASH_128(vb), XXHASH_128(vc) FROM mysql_catalog.binary_test.binary_test;
+```
+```text
++-----------------------------------------+-----------------------------------------+
+| XXHASH_128(vb)                          | XXHASH_128(vc)                          |
++-----------------------------------------+-----------------------------------------+
+|   8891052093862885505146213044715469136 |   8891052093862885505146213044715469136 |
+| -14492046026574147306325126754808553697 | -14492046026574147306325126754808553697 |
+|                                    NULL |                                    NULL |
++-----------------------------------------+-----------------------------------------+
+```
+