TODO.md

• We share the database cache between database pool writers and readers. But what if a writer modifies the database schema within a transaction, and a concurrent reader reads the cache? Bad things, isn't it? Write failing tests first, and fix the bug.
• Attach databases. Interesting question: what happens when one attaches a non-WAL db to a databasePool?
• SQLCipher: sqlite3_rekey is discouraged (ccgus/fmdb#547 (comment))
• What is the behavior inTransaction and inSavepoint behaviors in case of commit error? Code looks like we do not rollback, leaving the app in a weird state (out of Swift transaction block with a SQLite transaction that may still be opened).
• Query builder
  • SELECT readers., books. FROM ... JOIN ...
  • 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

GRDB 3.0

• Rename Request to FetchRequest, because Request is a bad name: swift-server/http#7 (comment)
• Rename RowConvertible, TableMapping, MutablePersistable and Persistable so that their names contain Record: FetchableRecord, TableRecord, MutablePersistableRecord, PersistableRecord?
• Not sure: Consider introducing RowDecodable and RowEncodable on top of FetchableRecord and MutablePersistableRecord. This would allow keeping fetching and persistence methods private in some files.

Not sure

• Think about supporting Cursor's 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:

• 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: ccgus/fmdb#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