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Ecto SQLite3 Extras

Helpful queries and Phoenix Live Dashboard integration for SQLite. It's like ecto_psql_extras but for SQLite instead of PostgreSQL.

Installation

The package can be installed by adding ecto_sqlite3_extras to your list of dependencies in mix.exs:

def deps do
  [
    {:ecto_sqlite3_extras, "~> 1.2.2"}
  ]
end

Integrating with Phoenix Live Dashboard

When you have ecto_sqlite3_extras in the list of dependencies for your Phoenix project that uses ecto_sqlite3, the Phoenix Live Dashboard will automatically show the tables produced by ecto_sqlite3_extras in the "Ecto Stats" tab. Magic!

Example of live dashboard with ecto_sqlite3_extras

Using from Elixir

If you don't have Phoenix Live Dashboard on the environment you want to inspect, you can use ecto_sqlite3_extras directly from the iex shell.

# run the query and print a nice ASCII table into stdout
EctoSQLite3Extras.table_size(MyProject.Repo)

# get the raw output of the query
EctoSQLite3Extras.table_size(MyProject.Repo, format: :raw)

# run the query on a remote node
EctoSQLite3Extras.table_size({MyProject.Repo, self()})

Example of ecto_sqlite3_extras usage with iex

Available queries

  1. total_size. The total size of all tables and indices. It's a summary table, it has only 2 columns: name and value. Rows:
    1. cells: The number of cells in the DB. Each value stored in the DB is represented as at least one cell. So, the number of cells correlates with the number of records in the DB.
    2. payload_size: How much space the actual useful payload takes in the DB.
    3. unused_size: How much space in the DB is reserved, not used yet, and can be used later to store more data. This is a surplus that occurs because SQLite allocates space for data in chunks ("pages").
    4. vacuum_size: How much space is unused and cannot be used for future data. You can run VACUUM command to reduce it.
    5. page_size: The total space occupied by all pages. Each page is a single chunk of space allocated by SQLite. This number is the sum of payload_size, unused_size, and vacuum_size.
    6. pages: The total number of pages.
    7. pages: leaf: The pages that store the actual data. Read SQLite Internals: Pages & B-trees to learn more.
    8. pages: internal: The pages that store ranges for leaf pages for a faster lookup. Sometimes also called "interior pages".
    9. pages: overflow: The pages that store chunks of big data that don't fit in a single leaf page.
    10. pages: table: The pages used for storing data for tables.
    11. pages: index: The pages used for storing indices.
  2. table_size. Information about the space used (and unused) by all tables. Based on the dbstat virtual table.
    1. name: The table name.
    2. payload_size.
    3. unused_size.
    4. vacuum_size.
    5. page_size.
    6. cells.
    7. pages.
    8. max_payload_size: The size of the biggest payload in the table.
  3. index_size. Size of all indices.
    1. name: The index name.
    2. table_name: The table where the index is defined.
    3. column_name: The name of the column being indexed. This column is NULL if the column is the rowid or an expression.
    4. payload_size.
    5. unused_size.
    6. page_size.
    7. cells.
    8. pages.
    9. max_payload_size.
  4. sequence_number. Sequence numbers of autoincrement columns. Generated based on the sqlite_sequence table. The query will fail if there are no autoincrement columns in the DB yet.
    1. table_name.
    2. sequence_number.
  5. pragma. List values of PRAGMAs (settings). Only includes the ones that have an integer or a boolean value. For brevity, the ones with the 0 (false) value are excluded from the output (based on the observation that this is the default value for most of the PRAGMAs). Check out the SQLite documentation to learn more about what each PRAGMA means: PRAGMA Statements.
    1. name: the name of the PRAGMA as listed in the SQLite documentation.
    2. value: the value of the PRAGMA. The true value is converted into 1 (and false is simply excluded).
  6. compile_options. List the compile-time options used when building SQLite, one option per row. The "SQLITE_" prefix is omitted from the returned option names. See exqlite docs on how to change these options.
  7. integrity_check. Run integrity checks on the database. Executes PRAGMA integrity_check and returns the resulting messages.

Acknowledgments

These are the projects that made ecto_sqlite3_extras possible:

  1. phoenix_live_dashboard is the reason why I made the project. I want my SQLite-powered Phoenix service to have the same nice-looking live dashboard as for PostgreSQL.
  2. exqlite provides SQLite support for Elixir. They enabled just for me the SQLITE_ENABLE_DBSTAT_VTAB option required for ecto_sqlite3_extras to work, literally making this project possible.
  3. ecto_psql_extras is a similar project for PostgreSQL. I shamelessly copied the project structure and tests, so that I can be sure that ecto_sqlite3_extras can be a drop-in replacement for ecto_psql_extras.