drop-index command and table.drop_index(index_name)

Closes #626

docs/changelog.rst

@@ -12,6 +12,7 @@ Unreleased
 - ``sqlite-utils query`` can now read the SQL query from standard input by passing ``-`` in place of the query, for example ``echo "select * from dogs" | sqlite-utils query dogs.db -``. (:issue:`765`)
 - ``sqlite-utils insert`` and ``sqlite-utils upsert`` now accept a ``--code`` option for :ref:`providing a block of Python code <cli_insert_code>` (or a path to a ``.py`` file) that defines a ``rows()`` function or ``rows`` iterable of rows to insert, as an alternative to importing from a file. (:issue:`684`)
 - ``sqlite-utils insert`` and ``sqlite-utils upsert`` now accept ``--type column-name type`` to :ref:`override the type automatically chosen when the table is created <cli_insert_csv_tsv_column_types>`. This is useful for CSV or TSV columns such as ZIP codes that look like integers but should be stored as ``TEXT`` to preserve leading zeros. (:issue:`131`)
+- New ``table.drop_index(name)`` method and ``sqlite-utils drop-index`` command for dropping an index by name. Both accept ``ignore=True``/``--ignore`` to ignore a missing index. (:issue:`626`)
 
 .. _v4_0:
 

docs/cli-reference.rst

@@ -19,7 +19,7 @@ This page lists the ``--help`` for every ``sqlite-utils`` CLI sub-command.
     go_first = [
         "query", "memory", "insert", "upsert", "bulk", "search", "transform", "extract",
         "schema", "insert-files", "analyze-tables", "convert", "tables", "views", "rows",
-        "triggers", "indexes", "create-database", "create-table", "create-index",
+        "triggers", "indexes", "create-database", "create-table", "create-index", "drop-index",
         "migrate", "enable-fts", "populate-fts", "rebuild-fts", "disable-fts"
     ]
     refs = {
@@ -46,6 +46,7 @@ This page lists the ``--help`` for every ``sqlite-utils`` CLI sub-command.
         "add-foreign-keys": "cli_add_foreign_keys",
         "index-foreign-keys": "cli_index_foreign_keys",
         "create-index": "cli_create_index",
+        "drop-index": "cli_drop_index",
         "enable-wal": "cli_wal",
         "enable-counts": "cli_enable_counts",
         "bulk": "cli_bulk",
@@ -1006,6 +1007,29 @@ See :ref:`cli_create_index`.
       -h, --help                 Show this message and exit.
 
 
+.. _cli_ref_drop_index:
+
+drop-index
+==========
+
+See :ref:`cli_drop_index`.
+
+::
+
+    Usage: sqlite-utils drop-index [OPTIONS] PATH TABLE INDEX
+
+      Drop an index by index name from the specified table
+
+      Example:
+
+          sqlite-utils drop-index chickens.db chickens idx_chickens_name
+
+    Options:
+      --ignore               Ignore if index does not exist
+      --load-extension TEXT  Path to SQLite extension, with optional :entrypoint
+      -h, --help             Show this message and exit.
+
+
 .. _cli_ref_migrate:
 
 migrate

docs/cli.rst

@@ -2615,6 +2615,19 @@ If your column names are already prefixed with a hyphen you'll need to manually
 
 Add the ``--analyze`` option to run ``ANALYZE`` against the index after it has been created.
 
+.. _cli_drop_index:
+
+Dropping indexes
+================
+
+You can drop an index from an existing table using the ``drop-index`` command:
+
+.. code-block:: bash
+
+    sqlite-utils drop-index mydb.db mytable idx_mytable_col1
+
+Use ``--ignore`` to ignore the error if the index does not exist on that table.
+
 .. _cli_fts:
 
 Configuring full-text search

docs/python-api.rst

@@ -2877,6 +2877,14 @@ Use ``if_not_exists=True`` to do nothing if an index with that name already exis
 
 Pass ``analyze=True`` to run ``ANALYZE`` against the new index after creating it.
 
+You can drop an index from a table using ``.drop_index(index_name)``:
+
+.. code-block:: python
+
+    db.table("dogs").drop_index("idx_dogs_name")
+
+Use ``ignore=True`` to ignore the error if the index does not exist.
+
 .. _python_api_analyze:
 
 Optimizing index usage with ANALYZE

sqlite_utils/cli.py

@@ -692,6 +692,34 @@ def create_index(
     )
 
 
+@cli.command(name="drop-index")
+@click.argument(
+    "path",
+    type=click.Path(exists=True, file_okay=True, dir_okay=False, allow_dash=False),
+    required=True,
+)
+@click.argument("table")
+@click.argument("index")
+@click.option("--ignore", help="Ignore if index does not exist", is_flag=True)
+@load_extension_option
+def drop_index(path, table, index, ignore, load_extension):
+    """
+    Drop an index by index name from the specified table
+
+    Example:
+
+    \b
+        sqlite-utils drop-index chickens.db chickens idx_chickens_name
+    """
+    db = sqlite_utils.Database(path)
+    _register_db_for_cleanup(db)
+    _load_extensions(db, load_extension)
+    try:
+        db.table(table).drop_index(index, ignore=ignore)
+    except OperationalError as ex:
+        raise click.ClickException(str(ex))
+
+
 @cli.command(name="enable-fts")
 @click.argument(
     "path",

sqlite_utils/db.py

@@ -3080,6 +3080,22 @@ class Table(Queryable):
             self.db.analyze(created_index_name)
         return self
 
+    def drop_index(self, index_name: str, ignore: bool = False):
+        """
+        Drop an index on this table.
+
+        :param index_name: Name of the index to drop
+        :param ignore: Set to ``True`` to ignore the error if the index does not exist
+        """
+        if index_name not in {index.name for index in self.indexes}:
+            if ignore:
+                return self
+            raise OperationalError(
+                "No index named {} on table {}".format(index_name, self.name)
+            )
+        self.db.execute("DROP INDEX {}".format(quote_identifier(index_name)))
+        return self
+
     def add_column(
         self,
         col_name: str,

tests/test_cli.py

@@ -291,6 +291,24 @@ def test_create_index(db_path):
         )
 
 
+def test_drop_index(db_path):
+    db = Database(db_path)
+    db["Gosh"].create_index(["c1"])
+    assert [index.name for index in db["Gosh"].indexes] == ["idx_Gosh_c1"]
+    result = CliRunner().invoke(cli.cli, ["drop-index", db_path, "Gosh", "idx_Gosh_c1"])
+    assert result.exit_code == 0
+    assert db["Gosh"].indexes == []
+
+    result = CliRunner().invoke(cli.cli, ["drop-index", db_path, "Gosh", "idx_Gosh_c1"])
+    assert result.exit_code == 1
+    assert "No index named idx_Gosh_c1" in result.output
+
+    result = CliRunner().invoke(
+        cli.cli, ["drop-index", db_path, "Gosh", "idx_Gosh_c1", "--ignore"]
+    )
+    assert result.exit_code == 0
+
+
 def test_create_index_analyze(db_path):
     db = Database(db_path)
     assert "sqlite_stat1" not in db.table_names()

tests/test_create.py

@@ -809,6 +809,34 @@ def test_create_index_if_not_exists(fresh_db):
     dogs.create_index(["name"], if_not_exists=True)
 
 
+def test_drop_index(fresh_db):
+    dogs = fresh_db["dogs"]
+    dogs.insert({"name": "Cleo", "twitter": "cleopaws", "age": 3, "is_good_dog": True})
+    dogs.create_index(["name"])
+    assert [index.name for index in dogs.indexes] == ["idx_dogs_name"]
+    dogs.drop_index("idx_dogs_name")
+    assert dogs.indexes == []
+
+
+def test_drop_index_ignore(fresh_db):
+    dogs = fresh_db["dogs"]
+    dogs.insert({"name": "Cleo"})
+    with pytest.raises(OperationalError, match="No index named idx_dogs_name"):
+        dogs.drop_index("idx_dogs_name")
+    dogs.drop_index("idx_dogs_name", ignore=True)
+
+
+def test_drop_index_wrong_table(fresh_db):
+    dogs = fresh_db["dogs"]
+    cats = fresh_db["cats"]
+    dogs.insert({"name": "Cleo"})
+    cats.insert({"name": "Misty"})
+    dogs.create_index(["name"])
+    with pytest.raises(OperationalError, match="No index named idx_dogs_name"):
+        cats.drop_index("idx_dogs_name")
+    assert [index.name for index in dogs.indexes] == ["idx_dogs_name"]
+
+
 def test_create_index_desc(fresh_db):
     dogs = fresh_db["dogs"]
     dogs.insert({"name": "Cleo", "twitter": "cleopaws", "age": 3, "is good dog": True})