fix issues

docs/en/sql-reference/functions/random-functions.md

@@ -60,4 +60,43 @@ Result:
 └────────────┴────────────┴──────────────┴────────────────┴─────────────────┴──────────────────────┘
 ```
 
+# Random functions for working with strings  {#random-functions-for-working-with-strings}
+
+## randomString {#random-string}
+
+## randomFixedString {#random-fixed-string}
+
+## randomPrintableASCII {#random-printable-ascii}
+
+## randomStringUTF8 {#random-string-utf8}
+
+## fuzzBits {#fuzzbits}
+
+**Syntax**
+
+``` sql
+fuzzBits([s], [prob])
+```
+Inverts bits of `s`, each with probability `prob`.
+
+**Parameters**
+- `s` - `String` or `FixedString`
+- `prob` - constant `Float32/64`
+
+**Returned value**
+Fuzzed string with same as s type.
+
+**Example**
+
+``` sql
+SELECT fuzzBits(materialize('abacaba'), 0.1)
+FROM numbers(3)
+```
+``` text
+┌─fuzzBits(materialize('abacaba'), 0.1)─┐
+│ abaaaja                               │
+│ a*cjab+                               │
+│ aeca2A                                │
+└───────────────────────────────────────┘
+
 [Original article](https://clickhouse.tech/docs/en/query_language/functions/random_functions/) <!--hide-->

src/Functions/fuzzBits.cpp

@@ -18,7 +18,6 @@ namespace DB
 namespace ErrorCodes
 {
     extern const int ILLEGAL_TYPE_OF_ARGUMENT;
-    extern const int TOO_LARGE_STRING_SIZE;
     extern const int ILLEGAL_COLUMN;
     extern const int DECIMAL_OVERFLOW;
 }
@@ -65,13 +64,15 @@ public:
 
     size_t getNumberOfArguments() const override { return 2; }
 
+    ColumnNumbers getArgumentsThatAreAlwaysConstant() const override { return {1}; } // indexing from 0
+
     DataTypePtr getReturnTypeImpl(const ColumnsWithTypeAndName & arguments) const override
     {
         if (!isStringOrFixedString(arguments[0].type))
             throw Exception(
                 "First argument of function " + getName() + " must be String or FixedString", ErrorCodes::ILLEGAL_TYPE_OF_ARGUMENT);
 
-        if (!arguments[1].column || !isFloat(arguments[1].type) || !isColumnConst(*arguments[1].column))
+        if (!arguments[1].column || !isFloat(arguments[1].type))
             throw Exception("Second argument of function " + getName() + " must be constant float", ErrorCodes::ILLEGAL_TYPE_OF_ARGUMENT);
 
         return arguments[0].type;
@@ -82,9 +83,13 @@ public:
 
     void executeImpl(Block & block, const ColumnNumbers & arguments, size_t result, size_t input_rows_count) override
     {
-        const auto col_in_untyped = block.getByPosition(arguments[0]).column;
+        auto col_in_untyped = block.getByPosition(arguments[0]).column;
         const double inverse_probability = assert_cast<const ColumnConst &>(*block.getByPosition(arguments[1]).column).getValue<double>();
 
+        if (const ColumnConst * col_in_untyped_const = checkAndGetColumnConstStringOrFixedString(col_in_untyped.get()))
+        {
+            col_in_untyped = col_in_untyped_const->getDataColumnPtr();
+        }
 
         if (const ColumnString * col_in = checkAndGetColumn<ColumnString>(col_in_untyped.get()))
         {
@@ -108,9 +113,9 @@ public:
 
             block.getByPosition(result).column = std::move(col_to);
         }
-        else if (const ColumnFixedString * col_fixed_in = checkAndGetColumn<ColumnFixedString>(col_in_untyped.get()))
+        else if (const ColumnFixedString * col_in_fixed = checkAndGetColumn<ColumnFixedString>(col_in_untyped.get()))
         {
-            const auto n = col_fixed_in->getN();
+            const auto n = col_in_fixed->getN();
             auto col_to = ColumnFixedString::create(n);
             ColumnFixedString::Chars & chars_to = col_to->getChars();
 
@@ -120,9 +125,11 @@ public:
 
             chars_to.resize(total_size);
 
-            const auto * ptr_in = col_fixed_in->getChars().data();
+            const auto * ptr_in = col_in_fixed->getChars().data();
             auto * ptr_to = chars_to.data();
             fuzzBits(ptr_in, ptr_to, chars_to.size(), inverse_probability);
+
+            block.getByPosition(result).column = std::move(col_to);
         }
         else
         {

tests/performance/fuzz_bits.xml

@@ -3,20 +3,12 @@
 
 
     <query>SELECT count() FROM zeros(1000000) WHERE NOT ignore(fuzzBits(randomString(10), 0.1))</query>
-    <query>SELECT count() FROM zeros(100000) WHERE NOT ignore(fuzzBits(randomString(100), 0.1))</query>
+    <query>SELECT count() FROM zeros(100000) WHERE NOT ignore(fuzzBits(randomString(100), 0.5))</query>
-    <query>SELECT count() FROM zeros(10000) WHERE NOT ignore(fuzzBits(randomString(1000), 0.1))</query>
+    <query>SELECT count() FROM zeros(10000) WHERE NOT ignore(fuzzBits(randomFixedString(1000), 0.1))</query>
-    <query>SELECT count() FROM zeros(1000) WHERE NOT ignore(fuzzBits(randomString(10000), 0.1))</query>
+    <query>SELECT count() FROM zeros(1000) WHERE NOT ignore(fuzzBits(randomFixedString(10000), 0.5))</query>
-    <query>SELECT count() FROM zeros(1000000) WHERE NOT ignore(fuzzBits(randomString(rand() % 10), 0.1))</query>
-    <query>SELECT count() FROM zeros(100000) WHERE NOT ignore(fuzzBits(randomString(rand() % 100), 0.1))</query>
-    <query>SELECT count() FROM zeros(10000) WHERE NOT ignore(fuzzBits(randomString(rand() % 1000), 0.1))</query>
 
     <query>SELECT count() FROM zeros(1000000) WHERE NOT ignore(fuzzBits(randomString(rand() % 10), 0.7))</query>
     <query>SELECT count() FROM zeros(100000) WHERE NOT ignore(fuzzBits(randomString(rand() % 100), 0.7))</query>
     <query>SELECT count() FROM zeros(10000) WHERE NOT ignore(fuzzBits(randomString(rand() % 1000), 0.7))</query>
 
-    <query>SELECT count() FROM zeros(1000000) WHERE NOT ignore(fuzzBits(randomFixedString(10), 0.5))</query>
-    <query>SELECT count() FROM zeros(100000) WHERE NOT ignore(fuzzBits(randomFixedString(100), 0.5))</query>
-    <query>SELECT count() FROM zeros(10000) WHERE NOT ignore(fuzzBits(randomFixedString(1000), 0.5))</query>
-    <query>SELECT count() FROM zeros(1000) WHERE NOT ignore(fuzzBits(randomFixedString(10000), 0.5))</query>
-
 </test>

tests/queries/0_stateless/01284_fuzz_bits.reference

@@ -1,2 +1,5 @@
+
 100
 String
+FixedString(10)
+1

tests/queries/0_stateless/01284_fuzz_bits.sql

@@ -1,4 +1,36 @@
-SELECT fuzzBits(toString('string'), 1); -- { serverError 43 }
+SELECT
-SELECT fuzzBits('', 0.3); -- { serverError 44 }
+  fuzzBits(toString('string'), 1);
-SELECT length(fuzzBits(randomString(100), 0.5));
+-- { serverError 43 }
-SELECT toTypeName(fuzzBits(randomString(100), 0.5));
+SELECT
+  fuzzBits('', 0.3);
+SELECT
+  length(fuzzBits(randomString(100), 0.5));
+SELECT
+  toTypeName(fuzzBits(randomString(100), 0.5));
+SELECT
+  toTypeName(fuzzBits(toFixedString('abacaba', 10), 0.9));
+
+SELECT
+  (
+    (0.3 * 0.99) * 8 * 10000 < sum
+    AND sum < (0.3 * 1.01) * 8 * 10000
+  ) AS res
+FROM
+  (
+    SELECT
+      arraySum(
+        id -> bitCount(
+          reinterpretAsUInt8(
+            substring(
+              fuzzBits(
+                arrayStringConcat(arrayMap(x -> toString('\0'), range(10000))),
+                0.3
+              ),
+              id + 1,
+              1
+            )
+          )
+        ),
+        range(10000)
+      ) as sum
+  )