![]() I dont think table scanning is necessary. Could someone explain to me what exactly is the bottleneck here? I see the sqlite.db-wal file growing to the full size of the migration (40GB), but again, that doesn't actually spell out a problem as far as I can tell. SQLite starts an implicit transaction automatically every time you run a SQL statement and commits it after execution. A column has a max BLOB size of 2Mib ( 1024 * 1024 * 2 bytes). Some additional context is that table being migrated ( media_chunk) is used to store chunks of files (the chunk column). The full transaction is below: import Sqlite3 from 'better-sqlite3'Ĭonst TIMESTAMP_SQLITE = `TIMESTAMP DATETIME DEFAULT(STRFTIME('%Y-%m-%dT%H:%M:%fZ', 'NOW'))`Ĭonst media chunks)`)ĪLTER TABLE media_chunk_new RENAME TO media_chunk ĬREATE INDEX media_chunk_range ON media_chunk (media_file_id, bytes_start) Ĭonsole.log() // just flush the last line of output There are no indexes on any of the tables, though there is a non null foreign key pointing at another table. insert into table_new select from table_old.select old data needed to set additional columns.create new table w/ two additional columns.The migration is essentially adding two columns to a table. I am working with a fairly massive amount of data for a single transaction (~40GB, 20,000 rows), but I don't understand what is actually slowing down the inserts or selects. Warning, during a transaction, the batch won't be committed until the transaction is committed await database.So in the process of writing a migration wrapped in a transaction for a local web app, I realized that the migration appears to perform inserts very fast when the transaction has a small number of inserts (on the order of 100 milliseconds per insert), but performs slower when the transaction gets larger (upwards of 4 seconds per insert). If you don't care about the result and worry about performance in big batches, you can use await mit(noResult: true) Update and delete), especially on Android where an extra SQL request is executed. Getting the result for each operation has a cost (id for insertion and number of changes for OnCreate: (Database db, int version) async, where: 'name = ?', whereArgs: ) īlete('Test', where: 'name = ?', whereArgs: ) String path = join(databasesPath, 'demo.db') ĭatabase database = await openDatabase(path, version: 1, Var databasesPath = await getDatabasesPath() See more information on opening a database.ĭemo code to perform Raw SQL queries // Get a location using getDatabasesPath.If you want to release resources, you can close the database. Many applications use one database and would never need to close it (it will be closed when the application is There is a basic migration mechanism to handle schema changes during opening. You call it inside another sqlite3preparev2() sqlite3finalize() block and even if its a legal operation, you commit transaction before all queries have been finished. Obtained by getDatabasesPath(), which is the default database directory on Android and the documents directory on iOS/MacOS. The second thing I want to mention here - sqlite3exec() is a wrapper around sqlite3preparev2(), sqlite3step() and sqlite3finalize(). If relative, this path is relative to the path Import sqflite.dart import 'package:sqflite/sqflite.dart' Ī SQLite database is a file in the file system identified by a path. In your flutter project add the dependency: dependencies:įor help getting started with Flutter, view the online notepad_sqflite: Simple flutter notepad working on iOS/Android/Windows/linux/Mac.Linux/Windows/DartVM support using sqflite_common_ffi.DB operation executed in a background thread on iOS and Android. ![]() Helpers for insert/query/update/delete queries.Automatic version managment during open.
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