Intro to SQLfor Organizing
Module 3 · Reading a Table: Schema, Preview, Row Counts › 3.5 Warm-up checkpoint
Subsection 3.5

Warm-up checkpoint

~3 min

Reading

The warm-up brings together the inspection skills from this module.

Find a table. Open it. Inspect it. Do not start by asking BigQuery to answer your organizing question. First, ask BigQuery to help you understand the table.

Use the warm-up checklist:

  • Find the table.
  • Open the table from the sidebar.
  • Use the Schema tab to count or review columns.
  • Use the Schema tab to identify data types.
  • Use the Details tab to find row count.
  • Use the Details tab to find storage size or total logical bytes.
  • Use Preview to skim sample records.
  • Format your starter SQL query.

You may see a Lineage tab. This course does not require lineage, but it can help teams understand data origin, transformations, dependencies, and downstream impact. In real organizations, lineage can support debugging, governance, compliance, and impact analysis.

For now, stay focused: schema, details, preview.

Checkpoint

Complete this sentence:

I should inspect schema, details, and preview before writing my query because [reason].

This warm-up is adapted from Rosario's SQL 101 BigQuery class. The original used a voter file. Use whatever table you committed to in Module 2.

Inspection facts to record

  1. How many columns? (Schema tab → Select All.)
  2. How many rows? (Details tab → Storage info → Number of rows.)
  3. What data types do you see? (List at least three from the Schema tab.)
  4. What is the disk size? (Details tab → Total logical bytes.)
  5. What is the last-modified date? (Details tab.)

Plain-language description template

The table [project.dataset.table] has about [N] rows and is [N] bytes on disk. Each row appears to represent [one row equals]. Three data types I see in the schema are [type1], [type2], [type3]. The field I plan to filter on later is [field name].

Knowledge check

Which tab has the row count?

Which BigQuery tab shows the total row count and disk size of a table?

You earned the Schema Reader badge

You can read a BigQuery table's schema, find its row count and disk size, and confirm in plain language what one row of the table represents. In Module 4 you'll finally write your first real SELECT against this table.

Next: Module 4 · Your First Query: SELECT, FROM, LIMIT

Continue to Module 4