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Merged
Yaraslaut merged 2 commits into from
Mar 2, 2026
Merged

Refactor SqlStatement to use SqlResultCursor #456

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Initial plan
Copilot Mar 2, 2026
c5f294d
rebase and fix code after all merges
Yaraslaut Mar 2, 2026
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7 changes: 3 additions & 4 deletions docs/usage.md
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Original file line number Diff line number Diff line change
Expand Up @@ -41,13 +41,12 @@ struct Record { int a; int b; int c; };
auto conn = SqlConnection {};
auto stmt = SqlStatement { conn };
stmt.Prepare("SELECT a, b, c FROM That WHERE a = ? OR b = ?");
stmt.Execute(42, 43);
auto cursor = stmt.Execute(42, 43);

SqlResultCursor cursor = stmt.GetResultCursor();
auto record = Record {};
cursor.BindOutputColumns<Record>(&record.a, &rcord.b, &record.c);
cursor.BindOutputColumns(&record.a, &record.b, &record.c);
while (cursor.FetchRow())
std::println("{}|{}|{}", a, b, c);
std::println("{}|{}|{}", record.a, record.b, record.c);
```

## SQL Query Builder
Expand Down
156 changes: 56 additions & 100 deletions src/Lightweight/DataMapper/DataMapper.hpp
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30 changes: 15 additions & 15 deletions src/Lightweight/SqlBackup/Backup.cpp
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Expand Up @@ -283,9 +283,9 @@ void ProcessTableBackup(BackupContext& ctx, SqlConnection& conn, SqlSchema::Tabl
// Build query with current offset for resumption
auto const selectQuery = BuildSelectQueryWithOffset(
formatter, conn.ServerType(), table.schema, tableName, table.columns, table.primaryKeys, processedRows);
stmt.ExecuteDirect(selectQuery);
auto cursor = stmt.ExecuteDirect(selectQuery);

while (stmt.FetchRow())
while (cursor.FetchRow())
{
if constexpr (DebugBackupWorker)
std::println(stderr, "DEBUG: FetchRow returned true for {}", tableName);
Expand All @@ -305,7 +305,7 @@ void ProcessTableBackup(BackupContext& ctx, SqlConnection& conn, SqlSchema::Tabl
{
try
{
auto valOpt = stmt.GetNullableColumn<SqlDynamicBinary<MaxBinaryLobBufferSize>>(i);
auto valOpt = cursor.GetNullableColumn<SqlDynamicBinary<MaxBinaryLobBufferSize>>(i);
if (valOpt)
{
row.emplace_back(std::vector<uint8_t>(valOpt->data(), valOpt->data() + valOpt->size()));
Expand All @@ -325,7 +325,7 @@ void ProcessTableBackup(BackupContext& ctx, SqlConnection& conn, SqlSchema::Tabl
}
else if (std::holds_alternative<Bool>(colDef.type))
{
auto valOpt = stmt.GetNullableColumn<bool>(i);
auto valOpt = cursor.GetNullableColumn<bool>(i);
if (valOpt)
row.emplace_back(*valOpt);
else
Expand All @@ -335,23 +335,23 @@ void ProcessTableBackup(BackupContext& ctx, SqlConnection& conn, SqlSchema::Tabl
|| std::holds_alternative<Smallint>(colDef.type)
|| std::holds_alternative<Tinyint>(colDef.type))
{
auto valOpt = stmt.GetNullableColumn<int64_t>(i);
auto valOpt = cursor.GetNullableColumn<int64_t>(i);
if (valOpt)
row.emplace_back(*valOpt);
else
row.emplace_back(std::monostate {});
}
else if (std::holds_alternative<Real>(colDef.type))
{
auto valOpt = stmt.GetNullableColumn<double>(i);
auto valOpt = cursor.GetNullableColumn<double>(i);
if (valOpt)
row.emplace_back(*valOpt);
else
row.emplace_back(std::monostate {});
}
else if (std::holds_alternative<NVarchar>(colDef.type) || std::holds_alternative<NChar>(colDef.type))
{
auto valOpt = stmt.GetNullableColumn<std::u16string>(i);
auto valOpt = cursor.GetNullableColumn<std::u16string>(i);
if (valOpt)
{
auto u8 = ToUtf8(*valOpt);
Expand All @@ -363,7 +363,7 @@ void ProcessTableBackup(BackupContext& ctx, SqlConnection& conn, SqlSchema::Tabl
else if (std::holds_alternative<Guid>(colDef.type))
{
// Read GUID columns using SqlGuid for proper ODBC binding, then convert to string
auto valOpt = stmt.GetNullableColumn<SqlGuid>(i);
auto valOpt = cursor.GetNullableColumn<SqlGuid>(i);
if (valOpt)
row.emplace_back(to_string(*valOpt));
else
Expand All @@ -374,7 +374,7 @@ void ProcessTableBackup(BackupContext& ctx, SqlConnection& conn, SqlSchema::Tabl
// Read Decimal as string directly to preserve full precision.
// Using double would lose precision for values exceeding ~15-17 significant digits,
// which is problematic for DECIMAL(38,10) and similar high-precision types.
auto valOpt = stmt.GetNullableColumn<std::string>(i);
auto valOpt = cursor.GetNullableColumn<std::string>(i);
if (valOpt)
row.emplace_back(*valOpt);
else
Expand All @@ -383,7 +383,7 @@ void ProcessTableBackup(BackupContext& ctx, SqlConnection& conn, SqlSchema::Tabl
else if (std::holds_alternative<Date>(colDef.type))
{
// Read Date using native type to avoid ODBC driver conversion issues.
auto valOpt = stmt.GetNullableColumn<SqlDate>(i);
auto valOpt = cursor.GetNullableColumn<SqlDate>(i);
if (valOpt)
row.emplace_back(std::format("{}", *valOpt));
else
Expand All @@ -398,7 +398,7 @@ void ProcessTableBackup(BackupContext& ctx, SqlConnection& conn, SqlSchema::Tabl
if (conn.ServerType() == SqlServerType::POSTGRESQL
|| conn.ServerType() == SqlServerType::MICROSOFT_SQL)
{
auto valOpt = stmt.GetNullableColumn<std::string>(i);
auto valOpt = cursor.GetNullableColumn<std::string>(i);
if (valOpt)
row.emplace_back(*valOpt);
else
Expand All @@ -407,7 +407,7 @@ void ProcessTableBackup(BackupContext& ctx, SqlConnection& conn, SqlSchema::Tabl
else
{
// Read Time using native type for other databases (e.g., SQLite).
auto valOpt = stmt.GetNullableColumn<SqlTime>(i);
auto valOpt = cursor.GetNullableColumn<SqlTime>(i);
if (valOpt)
row.emplace_back(std::format("{}", *valOpt));
else
Expand All @@ -419,7 +419,7 @@ void ProcessTableBackup(BackupContext& ctx, SqlConnection& conn, SqlSchema::Tabl
{
// Read DateTime/Timestamp using native type to avoid MS SQL Server ODBC driver
// issues with SQL_TYPE_TIMESTAMP to SQL_C_CHAR conversion (error 22003).
auto valOpt = stmt.GetNullableColumn<SqlDateTime>(i);
auto valOpt = cursor.GetNullableColumn<SqlDateTime>(i);
if (valOpt)
row.emplace_back(std::format("{}", *valOpt));
else
Expand All @@ -431,7 +431,7 @@ void ProcessTableBackup(BackupContext& ctx, SqlConnection& conn, SqlSchema::Tabl
// Read text/string types as strings directly.
// Note: We must not use SqlDynamicBinary for text types on PostgreSQL as its ODBC driver
// does not support reading TEXT as SQL_C_BINARY.
auto valOpt = stmt.GetNullableColumn<std::string>(i);
auto valOpt = cursor.GetNullableColumn<std::string>(i);
if (valOpt)
row.emplace_back(*valOpt);
else
Expand All @@ -440,7 +440,7 @@ void ProcessTableBackup(BackupContext& ctx, SqlConnection& conn, SqlSchema::Tabl
else
{
// Fallback for any unhandled types - try reading as string
auto valOpt = stmt.GetNullableColumn<std::string>(i);
auto valOpt = cursor.GetNullableColumn<std::string>(i);
if (valOpt)
row.emplace_back(*valOpt);
else
Expand Down
2 changes: 1 addition & 1 deletion src/Lightweight/SqlBackup/Common.cpp
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Expand Up @@ -116,7 +116,7 @@ bool DropTableIfExists(SqlConnection& conn,
// PostgreSQL which uses CASCADE syntax, and SQLite which ignores cascade.
auto dropSqls = formatter.DropTable(schema, tableName, /*ifExists=*/true, /*cascade=*/true);
for (auto const& sql: dropSqls)
SqlStatement { conn }.ExecuteDirect(sql);
(void) SqlStatement { conn }.ExecuteDirect(sql);
return true;
}
catch (std::exception const& e)
Expand Down
38 changes: 19 additions & 19 deletions src/Lightweight/SqlBackup/Restore.cpp
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Expand Up @@ -152,7 +152,7 @@ bool RestoreChunkData(RestoreContext& ctx, SqlConnection& workerConn, RestoreChu
if (hasIdentity)
{
identityTable = FormatTableName(ctx.schema, tableName);
SqlStatement { workerConn }.ExecuteDirect(std::format("SET IDENTITY_INSERT {} ON", identityTable));
(void) SqlStatement { workerConn }.ExecuteDirect(std::format("SET IDENTITY_INSERT {} ON", identityTable));
}
}

Expand All @@ -166,7 +166,7 @@ bool RestoreChunkData(RestoreContext& ctx, SqlConnection& workerConn, RestoreChu
stmt.Prepare(formatter.Insert(ctx.schema, tableName, fields, placeholders));

::Lightweight::detail::BatchManager batchManager(
[&](std::vector<SqlRawColumn> const& cols, size_t rows) { stmt.ExecuteBatch(cols, rows); },
[&](std::vector<SqlRawColumn> const& cols, size_t rows) { (void) stmt.ExecuteBatch(cols, rows); },
tableInfo.columns,
batchCapacity,
workerConn.ServerType());
Expand Down Expand Up @@ -221,14 +221,14 @@ bool RestoreChunkData(RestoreContext& ctx, SqlConnection& workerConn, RestoreChu

batchManager.Flush();
transaction.Commit();
stmt.CloseCursor();
// Cursor cleanup is handled by RAII
}

if (hasIdentity)
{
try
{
SqlStatement { workerConn }.ExecuteDirect(std::format("SET IDENTITY_INSERT {} OFF", identityTable));
(void) SqlStatement { workerConn }.ExecuteDirect(std::format("SET IDENTITY_INSERT {} OFF", identityTable));
}
catch (...) // NOLINT(bugprone-empty-catch)
{
Expand Down Expand Up @@ -277,12 +277,12 @@ bool RestoreChunkData(RestoreContext& ctx, SqlConnection& workerConn, RestoreChu
// Re-apply SQLite optimizations after reconnect
if (workerConn.ServerType() == SqlServerType::SQLITE)
{
SqlStatement { workerConn }.ExecuteDirect("PRAGMA synchronous = OFF");
SqlStatement { workerConn }.ExecuteDirect("PRAGMA journal_mode = WAL");
SqlStatement { workerConn }.ExecuteDirect("PRAGMA foreign_keys = OFF");
(void) SqlStatement { workerConn }.ExecuteDirect("PRAGMA synchronous = OFF");
(void) SqlStatement { workerConn }.ExecuteDirect("PRAGMA journal_mode = WAL");
(void) SqlStatement { workerConn }.ExecuteDirect("PRAGMA foreign_keys = OFF");
if (ctx.restoreSettings.cacheSizeKB > 0)
{
SqlStatement { workerConn }.ExecuteDirect(
(void) SqlStatement { workerConn }.ExecuteDirect(
std::format("PRAGMA cache_size = -{}", ctx.restoreSettings.cacheSizeKB));
}
}
Expand Down Expand Up @@ -311,12 +311,12 @@ void RestoreWorker(RestoreContext ctx, SqlConnection& workerConn)
// SQLite optimization: Turn off synchronization for faster restore
if (workerConn.ServerType() == SqlServerType::SQLITE)
{
SqlStatement { workerConn }.ExecuteDirect("PRAGMA synchronous = OFF");
SqlStatement { workerConn }.ExecuteDirect("PRAGMA journal_mode = WAL");
SqlStatement { workerConn }.ExecuteDirect("PRAGMA foreign_keys = OFF");
(void) SqlStatement { workerConn }.ExecuteDirect("PRAGMA synchronous = OFF");
(void) SqlStatement { workerConn }.ExecuteDirect("PRAGMA journal_mode = WAL");
(void) SqlStatement { workerConn }.ExecuteDirect("PRAGMA foreign_keys = OFF");
if (ctx.restoreSettings.cacheSizeKB > 0)
{
SqlStatement { workerConn }.ExecuteDirect(
(void) SqlStatement { workerConn }.ExecuteDirect(
std::format("PRAGMA cache_size = -{}", ctx.restoreSettings.cacheSizeKB));
}
}
Expand Down Expand Up @@ -414,7 +414,7 @@ void RestoreIndexes(SqlConnectionString const& connectionString,
std::string const sql = std::format(
R"(CREATE {}INDEX "{}" ON {} ({}))", uniqueKeyword, idx.name, formattedTableName, columnList);

SqlStatement { conn }.ExecuteDirect(sql);
(void) SqlStatement { conn }.ExecuteDirect(sql);

progress.Update({ .state = Progress::State::InProgress,
.tableName = tableName,
Expand Down Expand Up @@ -475,7 +475,7 @@ void ApplyDatabaseConstraints(SqlConnectionString const& connectionString,
{
auto sqls = formatter.AlterTable(schema, tableName, commands);
for (auto const& sql: sqls)
SqlStatement { conn }.ExecuteDirect(sql);
(void) SqlStatement { conn }.ExecuteDirect(sql);
}
catch (std::exception const& e)
{
Expand Down Expand Up @@ -597,7 +597,7 @@ std::set<std::string> CreateTablesInOrder(SqlConnection& conn,
std::string const formattedTableName = FormatTableName(schema, tableName);
try
{
SqlStatement { conn }.ExecuteDirect(
(void) SqlStatement { conn }.ExecuteDirect(
std::format("ALTER TABLE {} DROP CONSTRAINT IF EXISTS \"{}\"", formattedTableName, fkName));
}
catch (...) // NOLINT(bugprone-empty-catch)
Expand Down Expand Up @@ -638,7 +638,7 @@ std::set<std::string> CreateTablesInOrder(SqlConnection& conn,
{
try
{
SqlStatement { conn }.ExecuteDirect(sql);
(void) SqlStatement { conn }.ExecuteDirect(sql);
}
catch (std::exception const& e)
{
Expand Down Expand Up @@ -690,9 +690,9 @@ std::set<std::string> RecreateDatabaseSchema(SqlConnectionString const& connecti
if (isSQLite)
{
SqlStatement stmt { conn };
stmt.ExecuteDirect("PRAGMA synchronous = OFF");
stmt.ExecuteDirect("PRAGMA journal_mode = WAL");
stmt.ExecuteDirect("PRAGMA foreign_keys = OFF"); // Disable FKs during restore
(void) stmt.ExecuteDirect("PRAGMA synchronous = OFF");
(void) stmt.ExecuteDirect("PRAGMA journal_mode = WAL");
(void) stmt.ExecuteDirect("PRAGMA foreign_keys = OFF"); // Disable FKs during restore
}

auto const tableOrder = ComputeTableCreationOrder(tableMap, isSQLite);
Expand Down
2 changes: 1 addition & 1 deletion src/Lightweight/SqlConnection.cpp
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Expand Up @@ -270,7 +270,7 @@ void SqlConnection::PostConnect()
// Set a busy timeout to prevent "database is locked" errors during concurrent access.
// 60 seconds should be sufficient for most operations.
SqlStatement stmt(*this);
stmt.ExecuteDirect("PRAGMA busy_timeout = 60000");
[[maybe_unused]] auto cursor = stmt.ExecuteDirect("PRAGMA busy_timeout = 60000");

// We could also enable WAL mode here, but that changes the database file structure.
// However, for high-concurrency restoration, it is highly recommended.
Expand Down
4 changes: 2 additions & 2 deletions src/Lightweight/SqlMigration.cpp
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Expand Up @@ -145,7 +145,7 @@ void MigrationManager::ApplySingleMigration(MigrationBase const& migration)
{
try
{
stmt.ExecuteDirect(sqlScript);
(void) stmt.ExecuteDirect(sqlScript);
}
catch (SqlException const& ex)
{
Expand Down Expand Up @@ -197,7 +197,7 @@ void MigrationManager::RevertSingleMigration(MigrationBase const& migration)
{
try
{
stmt.ExecuteDirect(sqlScript);
(void) stmt.ExecuteDirect(sqlScript);
}
catch (SqlException const& ex)
{
Expand Down
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