Method read

src/Storages/StorageSQLite.cpp:104–137

Pipe StorageSQLite::read(
    const Names & column_names,
    const StorageSnapshotPtr & storage_snapshot,
    SelectQueryInfo & query_info,
    ContextPtr context_,
    QueryProcessingStage::Enum,
    size_t max_block_size,
    size_t /*num_streams*/)
{
    if (!sqlite_db)
        sqlite_db = openSQLiteDB(database_path, getContext(), /* throw_on_error */true);

    storage_snapshot->check(column_names);

    String query = transformQueryForExternalDatabase(
        query_info,
        column_names,
        storage_snapshot->metadata->getColumns().getOrdinary(),
        IdentifierQuotingStyle::DoubleQuotes,
        LiteralEscapingStyle::Regular,
        "",
        remote_table_name,
        context_);
    LOG_TRACE(log, "Query: {}", query);

    Block sample_block;
    for (const String & column_name : column_names)
    {
        auto column_data = storage_snapshot->metadata->getColumns().getPhysical(column_name);
        sample_block.insert({column_data.type, column_data.name});
    }

    return Pipe(std::make_shared<SQLiteSource>(sqlite_db, query, sample_block, max_block_size));
}


class SQLiteSink final : public SinkToStorage