Implement xRename for vec0 virtual table (fixes #43)

Enables ALTER TABLE RENAME on vec0 tables by renaming all shadow tables
(info, rowids, chunks, auxiliary, vector_chunks, metadata, rescore,
diskann, ivf) and updating cached names and prepared statements.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

tests/test-rename.py

@@ -0,0 +1,173 @@
+import sqlite3
+import pytest
+from helpers import _f32
+
+
+def _shadow_tables(db, prefix):
+    """Return sorted list of shadow table names for a given prefix."""
+    return sorted([
+        row[0] for row in db.execute(
+            r"select name from sqlite_master where name like ? escape '\' and type='table' order by 1",
+            [f"{prefix}\\__%"],
+        ).fetchall()
+    ])
+
+
+def test_rename_basic(db):
+    """ALTER TABLE RENAME should rename vec0 table and all shadow tables."""
+    db.execute("create virtual table v using vec0(a float[2], chunk_size=8)")
+    db.execute("insert into v(rowid, a) values (1, ?)", [_f32([0.1, 0.2])])
+    db.execute("insert into v(rowid, a) values (2, ?)", [_f32([0.3, 0.4])])
+
+    assert _shadow_tables(db, "v") == [
+        "v_chunks",
+        "v_info",
+        "v_rowids",
+        "v_vector_chunks00",
+    ]
+
+    db.execute("ALTER TABLE v RENAME TO v2")
+
+    # Old name should no longer work
+    with pytest.raises(sqlite3.OperationalError):
+        db.execute("select * from v")
+
+    # New name should work and return the same data
+    rows = db.execute(
+        "select rowid, distance from v2 where a match ? and k=10",
+        [_f32([0.1, 0.2])],
+    ).fetchall()
+    assert len(rows) == 2
+    assert rows[0][0] == 1  # closest match
+
+    # Shadow tables should all be renamed
+    assert _shadow_tables(db, "v2") == [
+        "v2_chunks",
+        "v2_info",
+        "v2_rowids",
+        "v2_vector_chunks00",
+    ]
+
+    # No old shadow tables should remain
+    assert _shadow_tables(db, "v") == []
+
+
+def test_rename_insert_after(db):
+    """Inserts and queries should work after rename."""
+    db.execute("create virtual table v using vec0(a float[2], chunk_size=8)")
+    db.execute("insert into v(rowid, a) values (1, ?)", [_f32([0.1, 0.2])])
+    db.execute("ALTER TABLE v RENAME TO v2")
+
+    # Insert into renamed table
+    db.execute("insert into v2(rowid, a) values (2, ?)", [_f32([0.3, 0.4])])
+
+    rows = db.execute(
+        "select rowid from v2 where a match ? and k=10",
+        [_f32([0.3, 0.4])],
+    ).fetchall()
+    assert len(rows) == 2
+    assert rows[0][0] == 2
+
+
+def test_rename_delete_after(db):
+    """Deletes should work after rename."""
+    db.execute("create virtual table v using vec0(a float[2], chunk_size=8)")
+    db.execute("insert into v(rowid, a) values (1, ?)", [_f32([0.1, 0.2])])
+    db.execute("insert into v(rowid, a) values (2, ?)", [_f32([0.3, 0.4])])
+    db.execute("ALTER TABLE v RENAME TO v2")
+
+    db.execute("delete from v2 where rowid = 1")
+    rows = db.execute(
+        "select rowid from v2 where a match ? and k=10",
+        [_f32([0.3, 0.4])],
+    ).fetchall()
+    assert len(rows) == 1
+    assert rows[0][0] == 2
+
+
+def test_rename_with_auxiliary(db):
+    """Rename should also rename the _auxiliary shadow table."""
+    db.execute(
+        "create virtual table v using vec0(a float[2], +name text, chunk_size=8)"
+    )
+    db.execute(
+        "insert into v(rowid, a, name) values (1, ?, 'hello')",
+        [_f32([0.1, 0.2])],
+    )
+
+    assert _shadow_tables(db, "v") == [
+        "v_auxiliary",
+        "v_chunks",
+        "v_info",
+        "v_rowids",
+        "v_vector_chunks00",
+    ]
+
+    db.execute("ALTER TABLE v RENAME TO v2")
+
+    # Auxiliary data should be accessible
+    rows = db.execute(
+        "select rowid, name from v2 where a match ? and k=10",
+        [_f32([0.1, 0.2])],
+    ).fetchall()
+    assert rows[0][0] == 1
+    assert rows[0][1] == "hello"
+
+    assert _shadow_tables(db, "v2") == [
+        "v2_auxiliary",
+        "v2_chunks",
+        "v2_info",
+        "v2_rowids",
+        "v2_vector_chunks00",
+    ]
+    assert _shadow_tables(db, "v") == []
+
+
+def test_rename_with_metadata(db):
+    """Rename should also rename metadata shadow tables."""
+    db.execute(
+        "create virtual table v using vec0(a float[2], tag text, chunk_size=8)"
+    )
+    db.execute(
+        "insert into v(rowid, a, tag) values (1, ?, 'a')",
+        [_f32([0.1, 0.2])],
+    )
+
+    assert _shadow_tables(db, "v") == [
+        "v_chunks",
+        "v_info",
+        "v_metadatachunks00",
+        "v_metadatatext00",
+        "v_rowids",
+        "v_vector_chunks00",
+    ]
+
+    db.execute("ALTER TABLE v RENAME TO v2")
+
+    rows = db.execute(
+        "select rowid, tag from v2 where a match ? and k=10",
+        [_f32([0.1, 0.2])],
+    ).fetchall()
+    assert rows[0][0] == 1
+    assert rows[0][1] == "a"
+
+    assert _shadow_tables(db, "v2") == [
+        "v2_chunks",
+        "v2_info",
+        "v2_metadatachunks00",
+        "v2_metadatatext00",
+        "v2_rowids",
+        "v2_vector_chunks00",
+    ]
+    assert _shadow_tables(db, "v") == []
+
+
+def test_rename_drop_after(db):
+    """DROP TABLE should work on a renamed table."""
+    db.execute("create virtual table v using vec0(a float[2], chunk_size=8)")
+    db.execute("insert into v(rowid, a) values (1, ?)", [_f32([0.1, 0.2])])
+    db.execute("ALTER TABLE v RENAME TO v2")
+    db.execute("DROP TABLE v2")
+
+    # Nothing should remain
+    assert _shadow_tables(db, "v2") == []