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table.xindexes property plus improved introspection documentation, closes #261
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Simon Willison
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3 changed files with 148 additions and 6 deletions
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@ -1449,6 +1449,11 @@ If you have loaded an existing table or view, you can use introspection to find
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>>> db["PlantType"]
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<Table PlantType (id, value)>
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.. _python_api_introspection_exists:
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.exists()
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---------
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The ``.exists()`` method can be used to find out if a table exists or not::
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>>> db["PlantType"].exists()
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@ -1456,6 +1461,11 @@ The ``.exists()`` method can be used to find out if a table exists or not::
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>>> db["PlantType2"].exists()
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False
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.. _python_api_introspection_count:
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.count
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------
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The ``.count`` property shows the current number of rows (``select count(*) from table``)::
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>>> db["PlantType"].count
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@ -1465,23 +1475,45 @@ The ``.count`` property shows the current number of rows (``select count(*) from
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This property will take advantage of :ref:`python_api_cached_table_counts` if the ``use_counts_table`` property is set on the database. You can avoid that optimization entirely by calling ``table.execute_count()`` instead of accessing the property.
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The ``.columns`` property shows the columns in the table or view::
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.. _python_api_introspection_columns:
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.columns
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--------
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The ``.columns`` property shows the columns in the table or view. It returns a list of ``Column(cid, name, type, notnull, default_value, is_pk)`` named tuples.
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::
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>>> db["PlantType"].columns
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[Column(cid=0, name='id', type='INTEGER', notnull=0, default_value=None, is_pk=1),
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Column(cid=1, name='value', type='TEXT', notnull=0, default_value=None, is_pk=0)]
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The ``.columns_dict`` property returns a dictionary version of this with just the names and types::
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.. _python_api_introspection_columns_dict:
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.columns_dict
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-------------
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The ``.columns_dict`` property returns a dictionary version of the columns with just the names and Python types::
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>>> db["PlantType"].columns_dict
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{'id': <class 'int'>, 'value': <class 'str'>}
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.. _python_api_introspection_pks:
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.pks
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----
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The ``.pks`` property returns a list of strings naming the primary key columns for the table::
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>>> db["PlantType"].pks
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['id']
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The ``.foreign_keys`` property shows if the table has any foreign key relationships. It is not available on views.
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.. _python_api_introspection_foreign_keys:
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.foreign_keys
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-------------
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The ``.foreign_keys`` property returns any foreign key relationships for the table, as a list of ``ForeignKey(table, column, other_table, other_column)`` named tuples. It is not available on views.
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::
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@ -1493,6 +1525,11 @@ The ``.foreign_keys`` property shows if the table has any foreign key relationsh
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ForeignKey(table='Street_Tree_List', column='qCaretaker', other_table='qCaretaker', other_column='id'),
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ForeignKey(table='Street_Tree_List', column='PlantType', other_table='PlantType', other_column='id')]
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.. _python_api_introspection_schema:
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.schema
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-------
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The ``.schema`` property outputs the table's schema as a SQL string::
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>>> print(db["Street_Tree_List"].schema)
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@ -1523,7 +1560,12 @@ The ``.schema`` property outputs the table's schema as a SQL string::
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FOREIGN KEY ("qCareAssistant") REFERENCES [qCareAssistant](id),
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FOREIGN KEY ("qLegalStatus") REFERENCES [qLegalStatus](id))
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The ``.indexes`` property shows you all indexes created for a table. It is not available on views.
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.. _python_api_introspection_indexes:
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.indexes
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--------
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The ``.indexes`` property returns all indexes created for a table, as a list of ``Index(seq, name, unique, origin, partial, columns)`` named tuples. It is not available on views.
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::
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@ -1535,7 +1577,38 @@ The ``.indexes`` property shows you all indexes created for a table. It is not a
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Index(seq=4, name='"Street_Tree_List_qCaretaker"', unique=0, origin='c', partial=0, columns=['qCaretaker']),
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Index(seq=5, name='"Street_Tree_List_PlantType"', unique=0, origin='c', partial=0, columns=['PlantType'])]
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The ``.triggers`` property lists database triggers. It can be used on both database and table objects.
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.. _python_api_introspection_xindexes:
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.xindexes
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---------
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The ``.xindexes`` property returns more detailed information about the indexes on the table, using the SQLite `PRAGMA index_xinfo() <https://sqlite.org/pragma.html#pragma_index_xinfo>`__ mechanism. It returns a list of ``XIndex(name, columns)`` named tuples, where ``columns`` is a list of ``XIndexColumn(seqno, cid, name, desc, coll, key)`` named tuples.
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::
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>>> db["ny_times_us_counties"].xindexes
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[
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XIndex(
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name='idx_ny_times_us_counties_date',
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columns=[
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XIndexColumn(seqno=0, cid=0, name='date', desc=1, coll='BINARY', key=1),
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XIndexColumn(seqno=1, cid=-1, name=None, desc=0, coll='BINARY', key=0)
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]
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),
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XIndex(
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name='idx_ny_times_us_counties_fips',
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columns=[
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XIndexColumn(seqno=0, cid=3, name='fips', desc=0, coll='BINARY', key=1),
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XIndexColumn(seqno=1, cid=-1, name=None, desc=0, coll='BINARY', key=0)
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]
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)
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]
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.. _python_api_introspection_triggers:
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.triggers
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---------
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The ``.triggers`` property lists database triggers. It can be used on both database and table objects. It returns a list of ``Trigger(name, table, sql)`` named tuples.
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::
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@ -1546,6 +1619,11 @@ The ``.triggers`` property lists database triggers. It can be used on both datab
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>>> db.triggers
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... similar output to db["authors"].triggers
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.. _python_api_introspection_triggers_dict:
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.triggers_dict
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--------------
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The ``.triggers_dict`` property returns the triggers for that table as a dictionary mapping their names to their SQL definitions.
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::
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@ -1564,6 +1642,11 @@ The same property exists on the database, and will return all triggers across al
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'authors_ad': 'CREATE TRIGGER [authors_ad] AFTER DELETE...',
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'authors_au': 'CREATE TRIGGER [authors_au] AFTER UPDATE'}
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.. _python_api_introspection_detect_fts:
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.detect_fts()
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-------------
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The ``detect_fts()`` method returns the associated SQLite FTS table name, if one exists for this table. If the table has not been configured for full-text search it returns ``None``.
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::
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@ -1571,12 +1654,22 @@ The ``detect_fts()`` method returns the associated SQLite FTS table name, if one
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>>> db["authors"].detect_fts()
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"authors_fts"
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.. _python_api_introspection_virtual_table_using:
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.virtual_table_using
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--------------------
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The ``.virtual_table_using`` property reveals if a table is a virtual table. It returns ``None`` for regular tables and the upper case version of the type of virtual table otherwise. For example::
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>>> db["authors"].enable_fts(["name"])
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>>> db["authors_fts"].virtual_table_using
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"FTS5"
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.. _python_api_introspection_has_counts_triggers:
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.has_counts_triggers
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--------------------
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The ``.has_counts_triggers`` property shows if a table has been configured with triggers for updating a ``_counts`` table, as described in :ref:`python_api_cached_table_counts`.
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::
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@ -68,6 +68,10 @@ ForeignKey = namedtuple(
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"ForeignKey", ("table", "column", "other_table", "other_column")
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)
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Index = namedtuple("Index", ("seq", "name", "unique", "origin", "partial", "columns"))
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XIndex = namedtuple("XIndex", ("name", "columns"))
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XIndexColumn = namedtuple(
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"XIndexColumn", ("seqno", "cid", "name", "desc", "coll", "key")
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)
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Trigger = namedtuple("Trigger", ("name", "table", "sql"))
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@ -863,6 +867,24 @@ class Table(Queryable):
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indexes.append(Index(**row))
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return indexes
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@property
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def xindexes(self):
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sql = 'PRAGMA index_list("{}")'.format(self.name)
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indexes = []
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for row in self.db.execute_returning_dicts(sql):
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index_name = row["name"]
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index_name_quoted = (
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'"{}"'.format(index_name)
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if not index_name.startswith('"')
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else index_name
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)
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column_sql = "PRAGMA index_xinfo({})".format(index_name_quoted)
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index_columns = []
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for info in self.db.execute(column_sql).fetchall():
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index_columns.append(XIndexColumn(*info))
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indexes.append(XIndex(index_name, index_columns))
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return indexes
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@property
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def triggers(self):
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return [
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@ -1,4 +1,4 @@
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from sqlite_utils.db import Index, View, Database
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from sqlite_utils.db import Index, View, Database, XIndex, XIndexColumn
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import pytest
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@ -93,6 +93,33 @@ def test_indexes(fresh_db):
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] == fresh_db["Gosh"].indexes
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def test_xindexes(fresh_db):
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fresh_db.executescript(
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"""
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create table Gosh (c1 text, c2 text, c3 text);
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create index Gosh_c1 on Gosh(c1);
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create index Gosh_c2c3 on Gosh(c2, c3 desc);
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"""
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)
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assert fresh_db["Gosh"].xindexes == [
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XIndex(
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name="Gosh_c2c3",
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columns=[
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XIndexColumn(seqno=0, cid=1, name="c2", desc=0, coll="BINARY", key=1),
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XIndexColumn(seqno=1, cid=2, name="c3", desc=1, coll="BINARY", key=1),
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XIndexColumn(seqno=2, cid=-1, name=None, desc=0, coll="BINARY", key=0),
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],
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),
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XIndex(
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name="Gosh_c1",
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columns=[
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XIndexColumn(seqno=0, cid=0, name="c1", desc=0, coll="BINARY", key=1),
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XIndexColumn(seqno=1, cid=-1, name=None, desc=0, coll="BINARY", key=0),
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],
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),
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]
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@pytest.mark.parametrize(
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"column,expected_table_guess",
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(
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