GRDB.swift/TODO.md

• Attach databases. Interesting question: what happens when one attaches a non-WAL db to a databasePool?

• SQLCipher: sqlite3_rekey is discouraged (https://github.com/ccgus/fmdb/issues/547#issuecomment-259219320)

• Query builder

  • date functions
  • NOW/CURRENT_TIMESTAMP
  • ROUND() http://marc.info/?l=sqlite-users&m=130419182719263
  • RANDOM() https://www.sqlite.org/lang_corefunc.html
  • GLOB https://www.sqlite.org/lang_expr.html
  • REGEXP https://www.sqlite.org/lang_expr.html
  • CASE x WHEN w1 THEN r1 WHEN w2 THEN r2 ELSE r3 END https://www.sqlite.org/lang_expr.html

• Write regression tests for #156 and #157

• Allow concurrent reads from a snapshot

• Decode NSDecimalNumber from text database values

• Check https://sqlite.org/sqlar.html

• filter(rowid:), filter(rowids:)

• Fix matchingRowIds

• Simplify Range extensions for Swift 4.1

• https://forums.swift.org/t/how-to-encode-objects-of-unknown-type/12253/6

• deprecate ScopeAdapter(base, scopes), because base.addingScopes has a better implementation

• Joins and full-text tables

• UPSERT https://www.sqlite.org/lang_UPSERT.html

• https://github.com/apple/swift-evolution/blob/master/proposals/0075-import-test.md

• Avoid code duplication: https://forums.swift.org/t/c-interoperability-combinations-of-library-and-os-versions/14029/4

• Allow joining methods on DerivableRequest

• DatabaseWriter.assertWriteAccess()

• Configuration.crashOnError = true

• Support for "INSERT INTO ... SELECT ...". For example:

  // INSERT INTO rigth (id, name) SELECT id, name FROM left
  let lefts = Left.select(Left.Columns.id, Left.Columns.name)
  try Right.insert(lefts)
  

• select values from a JSON column:

  let nesteds = try Record
      .select(Column("nested"), as: Nested.self)
      .fetchAll(db)
  

• Consider renaming dbQueue.inDatabase, dbPool.writeWithoutTransaction -> dbQueue/Pool.exclusive

• FetchedRecordsController diff algorithm: check https://github.com/RxSwiftCommunity/RxDataSources/issues/256

GRDB 4.0

• FTS: prefix queries
• Test NOT TESTED methods

Swift 4.2

• https://github.com/apple/swift-evolution/blob/master/proposals/0208-package-manager-system-library-targets.md
• https://github.com/apple/swift-evolution/blob/master/proposals/0201-package-manager-local-dependencies.md

Not sure

• HiddenColumnsAdapter

• Not sure: type safety for SQL expressions

  • Introduce some record protocol with an associated primary key type. Restrict filter(key:) methods to this type. Allow distinguishing FooId from BarId types.
  • Replace Column with TypedColumn. How to avoid code duplication (repeated types)? Keypaths?

• Encode/decode nested records/arrays/dictionaries as JSON?

• Cursor.underestimatedCount, which could speed up Array(cursor) and fetchAll()

• Support for OR ROLLBACK, and mismatch between the Swift depth and the SQLite depth of nested transactions/savepoint:

  try db.inTransaction {           // Swift depth: 1, SQLite depth: 1
      try db.execute("COMMIT")     // Swift depth: 1, SQLite depth: 0
      try db.execute("INSERT ...") // Should throw an error since this statement is no longer protected by a transaction
      try db.execute("SELECT ...") // Should throw an error since this statement is no longer protected by a transaction
      return .commit 
  }
  

  try db.inTransaction {
      try db.execute("INSERT OR ROLLBACK ...") // throws 
      return .commit // not executed because of error
  }   // Should not ROLLBACK since transaction has already been rollbacked
  

  try db.inTransaction {
      do {
          try db.execute("INSERT OR ROLLBACK ...") // throws
      } catch {
      }
      try db.execute("INSERT ...") // Should throw an error since this statement is no longer protected by a transaction
      try db.execute("SELECT ...") // Should throw an error since this statement is no longer protected by a transaction
      return .commit
  }
  

  try db.inTransaction {
      do {
          try db.execute("INSERT OR ROLLBACK ...") // throws
      } catch {
      }
      return .commit  // Should throw an error since transaction has been rollbacked and user's intent can not be applied
  }
  

Requires recompilation of SQLite:

• https://www.sqlite.org/c3ref/column_database_name.html could help extracting out of a row a subrow only made of columns that come from a specific table. Requires SQLITE_ENABLE_COLUMN_METADATA which is not set on the sqlite3 lib that ships with OSX.

Reading list:

• Documentation generation: https://twitter.com/jckarter/status/987525569196650496: cmark is the implementation the Swift compiler uses for doc comments etc.
• VACUUM (https://blogs.gnome.org/jnelson/)
• http://www.sqlite.org/intern-v-extern-blob.html
• https://sqlite.org/sharedcache.html
• Undo: https://www.sqlite.org/undoredo.html
• Undo: https://sqlite.org/sessionintro.html
• Swift, Xcode:List of Swift documentation keywords: https://swift.org/documentation/api-design-guidelines.html#special-instructions
• Swift, Xcode:Amazing tip from Xcode labs: add a EXCLUDED_SOURCE_FILE_NAMES build setting to conditionally exclude sources for different configuration: https://twitter.com/zats/status/74386298602026496
• SQLITE_ENABLE_SQLLOG: http://mjtsai.com/blog/2016/07/19/sqlite_enable_sqllog/
• Swift, Xcode: https://github.com/apple/swift/blob/master/docs/OptimizationTips.rst
• Associations: http://docs.diesel.rs/diesel/associations/index.html
• FTS: http://cocoamine.net/blog/2015/09/07/contentless-fts4-for-large-immutable-documents/
• pinyin: http://hustlzp.com/post/2016/02/ios-full-text-search-using-sqlite-fts4
• FetchedRecordsController: https://github.com/jflinter/Dwifft
• FetchedRecordsController: https://github.com/wokalski/Diff.swift (Faster)
• FetchedRecordsController: https://github.com/andre-alves/PHDiff
• React oddity: http://stackoverflow.com/questions/41721769/realm-update-object-without-updating-lists
• File protection: https://github.com/ccgus/fmdb/issues/262
• File protection: https://lists.apple.com/archives/cocoa-dev/2012/Aug/msg00527.html
• iOS apps are terminated every time they enter the background if they share an encrypted database with an app extension