ClickHouse

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#include "config.h"
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#if USE_ULID
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#include <Columns/ColumnFixedString.h>
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#include <DataTypes/DataTypeFixedString.h>
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#include <Functions/FunctionFactory.h>
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#include <Functions/FunctionHelpers.h>
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#include <Functions/IFunction.h>
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#include <Interpreters/Context.h>
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#include <ulid.h>
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namespace DB
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{
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namespace ErrorCodes
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{
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    extern const int NUMBER_OF_ARGUMENTS_DOESNT_MATCH;
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}
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class FunctionGenerateULID : public IFunction
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{
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public:
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    static constexpr size_t ULID_LENGTH = 26;
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    static constexpr auto name = "generateULID";
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    static FunctionPtr create(ContextPtr /*context*/)
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    {
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        return std::make_shared<FunctionGenerateULID>();
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    }
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    String getName() const override { return name; }
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    size_t getNumberOfArguments() const override { return 0; }
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    bool isVariadic() const override { return true; }
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    bool isDeterministic() const override { return false; }
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    bool isDeterministicInScopeOfQuery() const override { return false; }
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    bool isSuitableForShortCircuitArgumentsExecution(const DataTypesWithConstInfo & /*arguments*/) const override { return false; }
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    DataTypePtr getReturnTypeImpl(const DataTypes & arguments) const override
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    {
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        if (arguments.size() > 1)
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            throw Exception(
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                ErrorCodes::NUMBER_OF_ARGUMENTS_DOESNT_MATCH,
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                "Number of arguments for function {} doesn't match: passed {}, should be 0 or 1.",
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                getName(), arguments.size());
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        return std::make_shared<DataTypeFixedString>(ULID_LENGTH);
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    }
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    bool useDefaultImplementationForConstants() const override { return true; }
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    ColumnPtr executeImpl(const ColumnsWithTypeAndName & /*arguments*/, const DataTypePtr &, size_t input_rows_count) const override
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    {
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        auto col_res = ColumnFixedString::create(ULID_LENGTH);
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        auto & vec_res = col_res->getChars();
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        vec_res.resize(input_rows_count * ULID_LENGTH);
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        ulid_generator generator;
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        ulid_generator_init(&generator, 0);
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        for (size_t offset = 0, size = vec_res.size(); offset < size; offset += ULID_LENGTH)
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            ulid_generate(&generator, reinterpret_cast<char *>(&vec_res[offset]));
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        return col_res;
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    }
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};
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REGISTER_FUNCTION(GenerateULID)
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{
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    factory.registerFunction<FunctionGenerateULID>(FunctionDocumentation
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    {
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        .description=R"(
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Generates a Universally Unique Lexicographically Sortable Identifier (ULID).
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This function takes an optional argument, the value of which is discarded to generate different values in case the function is called multiple times.
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The function returns a value of type FixedString(26).
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)",
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        .examples{
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            {"ulid", "SELECT generateULID()", ""},
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            {"multiple", "SELECT generateULID(1), generateULID(2)", ""}},
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        .categories{"ULID"}
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    },
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    FunctionFactory::CaseSensitive);
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}
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}
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#endif
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