Question 1

How do spreadsheet tabs become BigQuery tables?

Accepted Answer

You choose one spreadsheet per connection, and each grid tab inside it becomes its own table, named after the tab. That matches how people really use spreadsheets, where a single file holds several related but separate things. If the sheet has headers turned on, row one supplies the column names. Without headers the columns arrive lettered, which is workable but rarely what you want in a data warehouse.

Question 2

How are spreadsheet column types decided in BigQuery?

Accepted Answer

Conservatively. Values default to strings unless a column carries a data validation rule marking it as a number, date or boolean, in which case that type is used. So if you want proper typing rather than everything arriving as text, adding validation rules on the sheet is the reliable way to get it. Doing that before the first sync saves work, because changing a column type later archives the old column and adds a new one beside it.

Question 3

What happens if someone reorders columns in the sheet?

Accepted Answer

This is the quiet failure to watch for. Fields are tracked by position, as column A, column B and so on, not by the header text. Insert or move a column and an existing mapping now reads something different, while the sync carries on happily writing wrong values under the right column names. After any structural edit, refresh the schema and check the mappings before the next run rather than trusting the totals.

Question 4

Does Polytomic read the whole sheet every time?

Accepted Answer

Yes, because there is nothing to read incrementally from. A spreadsheet keeps no change log, so each run reads it in full. Rows come in batches and reading stops after a long run of empty rows, which keeps a small used range inside a huge grid from being scanned to the limits. In practice this is fine. Sheets are tiny by BigQuery standards, so a full ETL run stays cheap enough to schedule often.

Question 5

Why load a spreadsheet into BigQuery?

Accepted Answer

Because spreadsheets hold the numbers no system owns. Targets, account tiering, manual corrections, the mapping between one tool's codes and another's. That data is real and reports depend on it, but it sits outside every pipeline. Loading it in makes those values joinable in SQL and gives you a governed copy with history, rather than a link to a file that anyone can restructure on a Friday afternoon.

Sync Google Sheets to BigQuery

Sync Google Sheets to BigQuery with Polytomic

One table per tab

Service account and go

Fresh snapshot each run

Or sync BigQuery to Google Sheets

Trusted by businesses worldwide

Step-by-step integration guide

Connect Google Sheets in Polytomic

Connect BigQuery in Polytomic

Create a sync between Google Sheets and BigQuery

Map fields and enable the sync

Frequently asked questions

The sync and ETL platform that does it all

Powerful data sync

Advanced analytics

Enterprise security

Easy setup

Ready to connect Google Sheets with BigQuery?