3c0603558c
DynamoDB limits the allowed magnitude and precision of numbers - valid decimal exponents are between -130 and 125 and up to 38 significant decimal digitst are allowed. In contrast, Scylla uses the CQL "decimal" type which offers unlimited precision. This can cause two problems: 1. Users might get used to this "unofficial" feature and start relying on it, not allowing us to switch to a more efficient limited-precision implementation later. 2. If huge exponents are allowed, e.g., 1e-1000000, summing such a number with 1.0 will result in a huge number, huge allocations and stalls. This is highly undesirable. After this patch, all tests in test/alternator/test_number.py now pass. The various failing tests which verify magnitude and precision limitations in different places (key attributes, non-key attributes, and arithmetic expressions) now pass - so their "xfail" tags are removed. Fixes #6794 Signed-off-by: Nadav Har'El <nyh@scylladb.com>
106 lines
3.9 KiB
C++
106 lines
3.9 KiB
C++
/*
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* Copyright 2019-present ScyllaDB
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*/
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/*
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* SPDX-License-Identifier: AGPL-3.0-or-later
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*/
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#pragma once
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#include <string>
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#include <string_view>
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#include <optional>
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#include "types/types.hh"
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#include "schema/schema_fwd.hh"
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#include "keys.hh"
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#include "utils/rjson.hh"
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#include "utils/big_decimal.hh"
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class position_in_partition;
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namespace alternator {
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enum class alternator_type : int8_t {
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S, B, BOOL, N, NOT_SUPPORTED_YET
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};
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struct type_info {
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alternator_type atype;
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data_type dtype;
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};
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struct type_representation {
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std::string ident;
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data_type dtype;
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};
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inline constexpr std::string_view scylla_paging_region(":scylla:paging:region");
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inline constexpr std::string_view scylla_paging_weight(":scylla:paging:weight");
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type_info type_info_from_string(std::string_view type);
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type_representation represent_type(alternator_type atype);
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bytes serialize_item(const rjson::value& item);
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rjson::value deserialize_item(bytes_view bv);
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std::string type_to_string(data_type type);
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bytes get_key_column_value(const rjson::value& item, const column_definition& column);
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bytes get_key_from_typed_value(const rjson::value& key_typed_value, const column_definition& column);
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rjson::value json_key_column_value(bytes_view cell, const column_definition& column);
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partition_key pk_from_json(const rjson::value& item, schema_ptr schema);
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clustering_key ck_from_json(const rjson::value& item, schema_ptr schema);
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position_in_partition pos_from_json(const rjson::value& item, schema_ptr schema);
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// If v encodes a number (i.e., it is a {"N": [...]}, returns an object representing it. Otherwise,
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// raises ValidationException with diagnostic.
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big_decimal unwrap_number(const rjson::value& v, std::string_view diagnostic);
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// try_unwrap_number is like unwrap_number, but returns an unset optional
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// when the given v does not encode a number.
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std::optional<big_decimal> try_unwrap_number(const rjson::value& v);
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// unwrap_bytes decodes byte value, on decoding failure it either raises api_error::serialization
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// iff from_query is true or returns unset optional iff from_query is false.
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// Therefore it's safe to dereference returned optional when called with from_query equal true.
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std::optional<bytes> unwrap_bytes(const rjson::value& value, bool from_query);
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// Check if a given JSON object encodes a set (i.e., it is a {"SS": [...]}, or "NS", "BS"
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// and returns set's type and a pointer to that set. If the object does not encode a set,
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// returned value is {"", nullptr}
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const std::pair<std::string, const rjson::value*> unwrap_set(const rjson::value& v);
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// Check if a given JSON object encodes a list (i.e., it is a {"L": [...]}
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// and returns a pointer to that list.
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const rjson::value* unwrap_list(const rjson::value& v);
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// Take two JSON-encoded numeric values ({"N": "thenumber"}) and return the
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// sum, again as a JSON-encoded number.
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rjson::value number_add(const rjson::value& v1, const rjson::value& v2);
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rjson::value number_subtract(const rjson::value& v1, const rjson::value& v2);
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// Take two JSON-encoded set values (e.g. {"SS": [...the actual set]}) and
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// return the sum of both sets, again as a set value.
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rjson::value set_sum(const rjson::value& v1, const rjson::value& v2);
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// Take two JSON-encoded set values (e.g. {"SS": [...the actual list]}) and
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// return the difference of s1 - s2, again as a set value.
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// DynamoDB does not allow empty sets, so if resulting set is empty, return
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// an unset optional instead.
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std::optional<rjson::value> set_diff(const rjson::value& v1, const rjson::value& v2);
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// Take two JSON-encoded list values (remember that a list value is
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// {"L": [...the actual list]}) and return the concatenation, again as
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// a list value.
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// Returns a null value if one of the arguments is not actually a list.
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rjson::value list_concatenate(const rjson::value& v1, const rjson::value& v2);
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namespace internal {
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struct magnitude_and_precision {
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int magnitude;
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int precision;
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};
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magnitude_and_precision get_magnitude_and_precision(std::string_view);
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}
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}
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