Preview Step Data

Description

The Data Preview drawer shows a step’s input or output table right inside the Visual Workflow Designer — a read-only grid of the first 100 rows with typed, sortable columns, docked at the bottom of the canvas. It’s built for the quick glance between edits: click any input or output table to look at it, check that a join produced the columns you expect, confirm a filter actually filtered, then keep building — without opening a full Table Explorer window for every look.

Open the Preview

There are four ways in, all landing in the same drawer:

Hover the step tile — a small browse (table) glyph fades in at the tile’s bottom-right corner. Click it.
Right-click the step and choose Preview Output Data.
In the Inspector, click the eye icon on any card under the step’s Inputs or Outputs section to preview that table.
On the step tile, click a table icon in the tile’s Inputs or Outputs band. (Dimension icons still open the dimension, and file icons still download the file.)

The drawer docks below the canvas. When you clicked a specific table, it shows that table; otherwise it loads the step’s first table output.

Browse From Step to Step

While the drawer is open, clicking any other step retargets the preview to that step’s output — one click per step. Walk down a chain of steps clicking each in turn and watch the data change shape at each stage.

To close the drawer, click ✕ in its header or press Esc. (If a step is selected, the first Esc closes the drawer and the next clears the selection.)

The header keeps the preview honest about what you’re seeing:

Table name and Showing first N of ~M rows — the tilde appears when the engine reports the total as an approximation.
Column count.
Table selector — pick which table to preview. A step that writes more than one table lists each output, with the first preselected. When you previewed an input, it appears at the top of the list ahead of the outputs and is preselected; switch to any output from there.
Refresh — refetch the preview on demand.
Open in Table Explorer — one-click escalation to the full explorer for whatever table the drawer shows (see below).
✕ — close the drawer.

Fresh After Every Run

If the step you’re previewing runs while the drawer is open, the preview refreshes automatically once when the run completes — so after a Run This Step, the drawer already shows the new data, on the same table you were viewing — including an input. Returning to a step whose output hasn’t changed reopens its preview without refetching.

When You Need More: Table Explorer

The preview is deliberately a glance, not a workbench — no editing, filtering, or downloading. When you need those, click Open in Table Explorer in the drawer header to open the same table in the full Table Explorer, with everything it offers.

Two cases where you’ll want that button:

Wide tables — the drawer renders the first 150 columns and notes that the rest are available in Table Explorer.
Deep dives — anything beyond the first 100 rows, or any slicing and filtering.

What the Drawer Shows When There’s Nothing to Show

This step has no table outputs — the step writes files or dimensions instead of tables, and you opened the preview without clicking a table. Clicking an input table still previews it.
No data yet — run the step to generate this table — the output table hasn’t been created yet. Run the step.
Table is empty — the table exists but has zero rows.

Next Steps

Advanced Workflows (Visual Workflow Designer) — the full canvas guide
Running one step in a workflow — run just the step you’re previewing