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15493872b2
value_to_json() converts CQL values to JSON for vector search filters. For decimal and varint types, it used rjson::parse() on the JSON string, which parses through a double and silently loses precision for values exceeding ~15 significant digits — producing wrong filter results. Additionally, for decimal type we need an exact string representation that preserves the original (unscaled, scale) pair, because partition keys use byte-level identity: different serialized representations of the same numeric value are distinct rows, so the filter must reproduce the exact representation stored in the key. Add big_decimal::to_string_canonical() which follows the Java BigDecimal toString() spec (JDK 8+), producing a bijective string representation that uses exponential notation for extreme scales instead of expanding trailing zeros (which could cause OOM). This could replace to_string(), but doing so has wider consequences (e.g. hash/equality contract for decimal_type) described in SCYLLADB-1574. Use it in value_to_json() for decimal_type, and use rjson::from_string() for varint_type, both bypassing the lossy double parse path. Tests cover the new to_string_canonical() and the filter fix, as well as existing decimal type behavior (key representation, clustering order, toJson) that we rely on and must not break. The CQL decimal type tests (test_type_decimal.py) also pass against Cassandra. Fixes: https://scylladb.atlassian.net/browse/SCYLLADB-1583 Refs: https://scylladb.atlassian.net/browse/SCYLLADB-1574 Closes scylladb/scylladb#29505
71 lines
2.3 KiB
C++
71 lines
2.3 KiB
C++
/*
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* Copyright (C) 2015-present ScyllaDB
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*/
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/*
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* SPDX-License-Identifier: LicenseRef-ScyllaDB-Source-Available-1.1
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*/
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#pragma once
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#include "multiprecision_int.hh"
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#include <boost/multiprecision/fwd.hpp>
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#include <seastar/core/sstring.hh>
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#include <compare>
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#include <concepts>
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using seastar::sstring;
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uint64_t from_varint_to_integer(const utils::multiprecision_int& varint);
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class big_decimal {
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private:
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int32_t _scale;
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boost::multiprecision::cpp_int _unscaled_value;
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private:
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std::strong_ordering tri_cmp_slow(const big_decimal& other) const;
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std::strong_ordering tri_cmp_positive_nonzero_different_scale(const big_decimal& other) const;
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public:
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enum class rounding_mode {
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HALF_EVEN,
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};
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explicit big_decimal(std::string_view text);
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big_decimal();
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big_decimal(int32_t scale, boost::multiprecision::cpp_int unscaled_value);
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big_decimal(std::integral auto v) : big_decimal(0, v) {}
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int32_t scale() const { return _scale; }
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const boost::multiprecision::cpp_int& unscaled_value() const { return _unscaled_value; }
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boost::multiprecision::cpp_rational as_rational() const;
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sstring to_string() const;
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// Exact string representation following the Java BigDecimal.toString() spec
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// (JDK 8+). Unlike to_string(), this is bijective: each (unscaled, scale)
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// pair maps to a unique string. Uses exponential notation when the exponent
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// is large or the scale is negative. This could replace to_string(), but
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// doing so has wider consequences (e.g. hash/equality contract for
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// decimal_type) described in SCYLLADB-1574.
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sstring to_string_canonical() const;
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std::strong_ordering operator<=>(const big_decimal& other) const;
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big_decimal& operator+=(const big_decimal& other);
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big_decimal& operator-=(const big_decimal& other);
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big_decimal operator+(const big_decimal& other) const;
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big_decimal operator-(const big_decimal& other) const;
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big_decimal operator-() const;
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big_decimal div(const ::uint64_t y, const rounding_mode mode) const;
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};
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template <>
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struct fmt::formatter<big_decimal> : fmt::formatter<string_view> {
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template <typename FormatContext>
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auto format(const big_decimal& v, FormatContext& ctx) const {
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return fmt::format_to(ctx.out(), "{}", v.to_string());
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}
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};
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