Data ManagementCompare

Data compare

Put two tables, two query results, or two pieces of SQL side by side and see exactly what differs. Rows added, removed or changed by key; columns and table options that moved; lines of SQL that don't match.

Compare · Data

5 added | 10 removed | 9 changedALLADDEDREMOVEDCHANGEDUNCHANGED

	id⏷	name⏷	value⏷	category⏷
~	80	item_80	~~800~~ → 801	0
~	60	item_60	~~600~~ → 601	0
3	86	item_86	860	1
−	93	item_93	930	3
5	82	item_82	820	2
−	94	item_94	940	4
+	102	new_item_102	10200	0
+	105	new_item_105	10500	0

105 rows

Row status in the gutter; changed cells show old → new. The right panel holds keys, filters and excluded columns.

Opening it

⌘ ⇧ C in the editor, or ⌘ K → Compare.
Header More Actions menu → Compare.
Right-click a table in the schema tree → Compare (it becomes the left source).
Results history → Compare Results (that result becomes the left source).

Compare is a tab, and there’s only one; opening it again reuses it. Three modes sit at the top: Data, Queries, Schema. Switching modes clears both sources.

Data

Pick a left and a right source from the same tree: Query Results (results from open tabs, kept for 24 hours) and every project → dataset → table. Search covers both.

Search results & tables… Search results & tables…

▾ Query Results 2

▸ Revenue Summary by Type 1

SELECT region, SUM(amount)… 2 hours ago · 56 rows

▾ ace-analytics

▾ warehouse 12

orders

orders_backup

Time Travel: 2026-08-27 09:00

Left source picker. Time Travel appears under a selected table, up to 7 days back.

Choosing key columns

Tick the Key Columns that identify a row. Only columns present in both sources with a scalar type qualify; STRUCT and ARRAY columns never do. Likely key columns are suggested, but nothing is selected for you; at least one key is required before Compare enables.

Compare without keys (row hash) hashes whole rows instead: you get added and removed rows only, never changed.

Narrowing the scan

Partitioning: for partitioned tables, a date range per side or Same filter for both, with presets from Today to Last 90 days. A table that requires a partition filter gets the last year by default.
Filters: WHERE conditions such as status = 'active', ANDed together. They’re passed through as written; a bad expression fails when the comparison runs.
Excluded Columns: dropped from the comparison and from the results. Use it for updated_at and other columns that differ on every write.

Where the comparison runs

Small comparisons run in the browser at no cost; larger ones run as a query in BigQuery, so only differences come back and Unchanged is empty. The footer shows the dry-run cost, and Open comparison SQL in new tab shows the generated query.

Reading the results

The bar reads 5 added | 10 removed | 9 changed; the buttons filter to All / Added / Removed / Changed / Unchanged. Rows are tinted green (added, right only), red (removed, left only) or amber (changed); a changed cell shows the old value struck through, then the new one. After a run, Estimate Cost / Run Comparison in the right panel re-run with new keys or filters.

Export offers CSV (with diff), one row per difference with + − ~ markers, and Google Sheets with left and right columns side by side. The copy button puts the visible rows on the clipboard as TSV with the same markers.

Schema

Choose two tables and Compare. The icons in the search field switch to views or routines. Column rows are marked + in right only, − in left only, ~ modified, with All (31) and per-status counts to filter. Type, mode and description are compared per column; nested RECORD fields are listed by dotted path.

	Column Name⏷	Type⏷	Mode⏷	Description⏷
+	defect_type_key	STRING	NULLABLE	Surrogate key for the defect type dimension
+	classification.severity_level	INTEGER	NULLABLE	Numeric severity level (1=lowest to 5=highest)
~	description	STRING	~~REQUIRED~~ → NULLABLE	Full description of what this defect type means
−	category_key	STRING	REQUIRED	Primary key: Normalized category code

Table options that differ appear above the column grid.

Table Options Changed lists partitioning, clustering, description, labels and require partition filter as old → new. Copy as DDL turns the column differences into ALTER TABLE … ADD COLUMN / DROP COLUMN / ALTER COLUMN … SET DATA TYPE statements that would bring the left table to the right one. Views also get a diff of their definition; routines get only that.

Queries

Pick from Open Tabs or Paste SQL on each side. The result is two editors with line numbers, lines tinted green (added), red (removed) or amber (modified), with counts in the header and Copy Diff. Lines are matched by position, so an inserted line near the top shows as a run of modified lines below it; the badges count net additions and removals instead.