This page describes Calíope 1.5, the version we are building right now. 1.4 is finished and in App Review, and the store serves 1.3 on the Mac and 1.2 on iPad. The changelog says which version each feature landed in.

Adds an “Open in Calíope” button to every topic. It only works with the app installed.

Visual EXPLAIN

Visualize Execution Plan

Displays the query optimizer's operation tree.

Where it is: SQL Editor › Visual EXPLAIN

With a SELECT query in the SQL Editor, click Visual EXPLAIN in the toolbar. Calíope runs EXPLAIN FORMAT=JSON (MySQL/MariaDB syntax) and opens the Visual EXPLAIN tab showing the plan's node tree.

Each node displays the access type, the index used (if any), the estimated row count, and the cost in milliseconds.

Navigating the tree:
- macOS: the mouse wheel or a two-finger pinch on the trackpad to zoom; drag to pan the canvas.
- iPad: pinch with two fingers to zoom, and drag with one finger to pan.
- On both: the − and + buttons in the toolbar, with the percentage between them, and Fit to window to frame the whole tree. The shortcuts are ⌘−, ⌘+ and ⌘0.

The scale runs from 18 % to 350 %, which is plenty of room for plans with many levels of nesting.

Keywords: explain, plan, optimizer, tree, JSON explain, zoom, pan, navigate, pinch

Interpreting Access Colors

Node colors indicate the efficiency of data access.

Where it is: Visual EXPLAIN › Color Legend

Visual EXPLAIN nodes are colored according to the access type: green = optimized access (ref, eq_ref, const), yellow = range scan (index range scan), orange = index scan (full index traversal), red = full table scan (no index, worst case).

A red node indicates an optimization opportunity, typically by adding an index.

Keywords: full scan, range, index, colors, optimization, explain