refactor: call the benchmark's comparison the legacy format
The README, a comment in :Reflect and tests/Benchmark named the project whose transaction log this library replaces. That name means nothing to people using the library, so the benchmark's reference implementation is now the `Legacy` namespace, its column reads `legacy ms`, and the prose describes it as the hand-rolled iostream format Crafter.DB replaces. Timings and logic are unchanged; the suite still passes. Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>
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README.md
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README.md
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@ -1,6 +1,6 @@
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# Crafter.DB
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An embedded, typed table store for C++26: a table is a plain struct, a file is a memory-mapped array of fixed-width rows, queries are C++. Built for the Catcrafts projects (it replaces Nostro's hand-rolled transaction log) and distributed as one C++ module, `Crafter.DB`.
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An embedded, typed table store for C++26: a table is a plain struct, a file is a memory-mapped array of fixed-width rows, queries are C++. Built for the Catcrafts projects (it replaces a hand-rolled, iostream-based transaction log) and distributed as one C++ module, `Crafter.DB`.
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- **Structs are the schema.** Any aggregate with a `version` is a table. No macros, no registration, no code generation: member names, types and offsets are derived at compile time.
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- **Fixed-width rows, out-of-line strings.** Every row is `rowSize` bytes. Strings and blobs live in a heap region; the row holds a 16-byte handle that keeps values of up to 12 bytes, and the first 4 bytes of longer ones, inline, so `iban == x` is one 8-byte compare per row.
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@ -194,18 +194,18 @@ One file per table: a 4 KiB header (magic, format and schema version, fingerprin
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## Performance
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`tests/Benchmark` compares Crafter.DB with a cleaned-up copy of Nostro's format (iostream, 2-byte length-prefixed strings) on 100 000 transactions, warm cache, one run on a Xeon w7-3465X:
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`tests/Benchmark` compares Crafter.DB with a cleaned-up copy of the legacy format it replaces (iostream, 2-byte length-prefixed strings, linear scans) on 100 000 transactions, warm cache, one run on a Xeon w7-3465X:
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| Operation | Nostro | Crafter.DB | Note |
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| Operation | Legacy | Crafter.DB | Note |
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| --- | --- | --- | --- |
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| append 100 000 rows | 16.5 ms | 11.1 ms | Crafter.DB includes `fdatasync`; Nostro syncs nothing |
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| append 100 000 rows | 16.5 ms | 11.1 ms | Crafter.DB includes `fdatasync`; the legacy format syncs nothing |
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| last timestamp, 1000 × open + read | 1.9 ms | 30.0 ms | opening a mapped table costs one `mmap` per extent (about 20 for this size); open once per process |
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| load all, materialised | 36.0 ms | 10.4 ms | zero-copy scan of two columns: 0.8 ms |
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| time range, 10 % of rows | 10.0 ms | 0.9 ms | binary search + contiguous slice |
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| `iban == x` | 16.2 ms | 0.23–0.30 ms | 2–3 ns per row |
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| time range + `iban == x` | 11.2 ms | 0.03 ms | |
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File size for that table: 17.2 MB against Nostro's 9.3 MB (fixed-width handles plus the slack of the last extents; `Compact()` right-sizes).
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File size for that table: 17.2 MB against the legacy format's 9.3 MB (fixed-width handles plus the slack of the last extents; `Compact()` right-sizes).
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## Building
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@ -72,7 +72,7 @@ export namespace Crafter::DB {
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return raw.substr(dot + 1, end - dot - 1);
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}
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// The type's qualified name as the compiler spells it ("Nostro::Transaction").
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// The type's qualified name as the compiler spells it ("Ledger::Transaction").
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// Used in diagnostics only, so the exact spelling is not load-bearing.
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template<class T>
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consteval std::string_view TypeName() {
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@ -1,9 +1,9 @@
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// SPDX-License-Identifier: LGPL-3.0-only
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// SPDX-FileCopyrightText: Copyright (C) 2026 Catcrafts®
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// Crafter.DB against a cleaned-up copy of Nostro's hand-rolled format
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// Crafter.DB against a cleaned-up copy of the legacy format it replaces
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// (iostream, uint16-prefixed strings inline, linear scans) on the five
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// operations Nostro performs. Prints a table; never fails. Runs on 100k
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// operations that log served. Prints a table; never fails. Runs on 100k
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// rows so a full suite stays fast; raise `rowCount` for a serious run.
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import Crafter.DB;
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@ -49,8 +49,8 @@ namespace {
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return rows;
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}
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// --- the Nostro format, cleaned up -----------------------------------------
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namespace Nostro {
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// --- the legacy format, cleaned up -----------------------------------------
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namespace Legacy {
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void WriteString(std::ofstream& file, std::string_view str) {
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const std::uint16_t size = static_cast<std::uint16_t>(str.size());
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file.write(reinterpret_cast<const char*>(&size), sizeof(size));
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@ -139,7 +139,7 @@ namespace {
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struct Line {
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std::string name;
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double nostro;
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double legacy;
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double crafter;
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std::string note;
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};
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@ -149,7 +149,7 @@ int main() {
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const fs::path dir = fs::temp_directory_path() / "crafter-db-benchmark";
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fs::remove_all(dir);
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fs::create_directories(dir);
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const fs::path nostroPath = dir / "nostro.bin";
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const fs::path legacyPath = dir / "legacy.bin";
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const fs::path crafterPath = dir / "crafter.cdb";
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const std::vector<Transaction> rows = MakeRows();
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const std::string_view wantedIban = rows[rowCount / 2].iban;
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@ -160,84 +160,84 @@ int main() {
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// append
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{
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const double nostro = Millis([&] { Nostro::Save(nostroPath, rows); });
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const double legacy = Millis([&] { Legacy::Save(legacyPath, rows); });
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const double crafter = Millis([&] {
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DB::Table<Transaction> table(crafterPath);
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table.Append(rows);
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table.Flush();
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});
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lines.push_back({ std::format("append {} rows", rowCount), nostro, crafter, "incl. open, Crafter.DB incl. fdatasync" });
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lines.push_back({ std::format("append {} rows", rowCount), legacy, crafter, "incl. open, Crafter.DB incl. fdatasync" });
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}
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// last timestamp (1000 opens each)
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{
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const double nostro = Millis([&] { for (std::int32_t i = 0; i < 1000; i++) sink += Nostro::LastTime(nostroPath).time_since_epoch().count() & 1; });
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const double legacy = Millis([&] { for (std::int32_t i = 0; i < 1000; i++) sink += Legacy::LastTime(legacyPath).time_since_epoch().count() & 1; });
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const double crafter = Millis([&] {
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for (std::int32_t i = 0; i < 1000; i++) {
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const DB::Table<Transaction> table(crafterPath, { .readOnly = true });
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sink += table.Back()[&Transaction::timePoint].time_since_epoch().count() & 1;
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}
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});
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lines.push_back({ "last timestamp (1000x open+read)", nostro, crafter, "open dominates both" });
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lines.push_back({ "last timestamp (1000x open+read)", legacy, crafter, "open dominates both" });
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}
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DB::Table<Transaction> table(crafterPath, { .readOnly = true });
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// load all
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{
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const double nostro = Millis([&] { sink += Nostro::LoadAll(nostroPath).size(); });
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const double legacy = Millis([&] { sink += Legacy::LoadAll(legacyPath).size(); });
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const double crafter = Millis([&] { sink += table.Materialize().size(); });
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double zeroCopy = Millis([&] {
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std::int64_t total = 0;
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for (DB::Row<Transaction> row : table) total += row[&Transaction::amount] + static_cast<std::int64_t>(row[&Transaction::iban].Length());
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sink += static_cast<std::size_t>(total & 1);
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});
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lines.push_back({ "load all (materialised)", nostro, crafter, std::format("zero-copy scan of two columns: {:.2f} ms", zeroCopy) });
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lines.push_back({ "load all (materialised)", legacy, crafter, std::format("zero-copy scan of two columns: {:.2f} ms", zeroCopy) });
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}
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// time range (10% of rows)
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{
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std::size_t nostroCount = 0;
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std::size_t legacyCount = 0;
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std::size_t crafterCount = 0;
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const double nostro = Millis([&] { nostroCount = Nostro::LoadRange(nostroPath, from, to).size(); });
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const double legacy = Millis([&] { legacyCount = Legacy::LoadRange(legacyPath, from, to).size(); });
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const double crafter = Millis([&] { crafterCount = table.Range<&Transaction::timePoint>(from, to).Materialize().size(); });
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lines.push_back({ "time range (10% of rows, materialised)", nostro, crafter, std::format("{} / {} rows", nostroCount, crafterCount) });
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lines.push_back({ "time range (10% of rows, materialised)", legacy, crafter, std::format("{} / {} rows", legacyCount, crafterCount) });
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}
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// iban ==
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{
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std::size_t nostroCount = 0;
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std::size_t legacyCount = 0;
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std::size_t keyCount = 0;
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std::size_t exprCount = 0;
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std::size_t viewCount = 0;
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const double nostro = Millis([&] { nostroCount = Nostro::LoadByIban(nostroPath, wantedIban).size(); });
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const double legacy = Millis([&] { legacyCount = Legacy::LoadByIban(legacyPath, wantedIban).size(); });
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const double withKey = Millis([&] {
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const DB::Key key(wantedIban);
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keyCount = table.Where([&](DB::Row<Transaction> r) { return r[&Transaction::iban] == key; }).Count();
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});
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const double withExpression = Millis([&] { exprCount = table.Where(iban == wantedIban).Count(); });
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const double withView = Millis([&] { viewCount = table.Where([&](DB::Row<Transaction> r) { return r[&Transaction::iban] == wantedIban; }).Count(); });
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lines.push_back({ "iban == x (lambda + Key)", nostro, withKey, std::format("{} / {} rows, {:.1f} ns/row", nostroCount, keyCount, withKey * 1e6 / rowCount) });
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lines.push_back({ "iban == x (expression)", nostro, withExpression, std::format("{} rows, {:.1f} ns/row", exprCount, withExpression * 1e6 / rowCount) });
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lines.push_back({ "iban == x (lambda + string_view)", nostro, withView, std::format("{} rows, {:.1f} ns/row", viewCount, withView * 1e6 / rowCount) });
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lines.push_back({ "iban == x (lambda + Key)", legacy, withKey, std::format("{} / {} rows, {:.1f} ns/row", legacyCount, keyCount, withKey * 1e6 / rowCount) });
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lines.push_back({ "iban == x (expression)", legacy, withExpression, std::format("{} rows, {:.1f} ns/row", exprCount, withExpression * 1e6 / rowCount) });
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lines.push_back({ "iban == x (lambda + string_view)", legacy, withView, std::format("{} rows, {:.1f} ns/row", viewCount, withView * 1e6 / rowCount) });
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}
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// range + iban
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{
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std::size_t nostroCount = 0;
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std::size_t legacyCount = 0;
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std::size_t crafterCount = 0;
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const double nostro = Millis([&] {
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for (const Transaction& tr : Nostro::LoadRange(nostroPath, from, to)) nostroCount += tr.iban == wantedIban ? 1 : 0;
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const double legacy = Millis([&] {
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for (const Transaction& tr : Legacy::LoadRange(legacyPath, from, to)) legacyCount += tr.iban == wantedIban ? 1 : 0;
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});
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const double crafter = Millis([&] { crafterCount = table.Where(timePoint >= from && timePoint <= to && iban == wantedIban).Count(); });
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lines.push_back({ "time range + iban == x", nostro, crafter, std::format("{} / {} rows", nostroCount, crafterCount) });
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lines.push_back({ "time range + iban == x", legacy, crafter, std::format("{} / {} rows", legacyCount, crafterCount) });
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}
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std::println("{:<42} {:>12} {:>12} {:>8} {}", "operation", "nostro ms", "crafter ms", "speedup", "note");
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std::println("{:<42} {:>12} {:>12} {:>8} {}", "operation", "legacy ms", "crafter ms", "speedup", "note");
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for (const Line& line : lines) {
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std::println("{:<42} {:>12.3f} {:>12.3f} {:>7.1f}x {}", line.name, line.nostro, line.crafter, line.nostro / std::max(line.crafter, 0.0001), line.note);
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std::println("{:<42} {:>12.3f} {:>12.3f} {:>7.1f}x {}", line.name, line.legacy, line.crafter, line.legacy / std::max(line.crafter, 0.0001), line.note);
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}
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std::println("files: nostro {} bytes, crafter {} bytes", fs::file_size(nostroPath), fs::file_size(crafterPath));
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std::println("files: legacy {} bytes, crafter {} bytes", fs::file_size(legacyPath), fs::file_size(crafterPath));
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std::println("(sink {})", sink & 1);
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fs::remove_all(dir);
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