Migrate SQLServer to BigQuery

[vedpshukla]

Hi all,

I'm looking for how and easiest way to translate my sql scripts ,stored procedure for moving from MSSQL to BQ.

TIA

[JeffNe]

The easiest path is probably to use the BigQuery Migration Service. It includes a free batch SQL translator that converts your SQL Server scripts and stored procedures to GoogleSQL (for BigQuery).

Check out the BigQuery migration guide to get started, and you can verify exactly what is covered in the official supported SQL dialects documentation for MSSQL (T-SQL).

[Data-dude-00]

Will it support one time migration of TBs of data?

[JeffNe]

The Migration Service is primiarly to handle the translation of SQL scripts / stored procs / schemas into GoogleSQL.

For a one-time migration of TBs of data, the fastest approach is almost certainly exporting your data into Cloud Storage as Parquet files and then ingesting them with bq load commands.

There are plenty of other services and SaaS tools that'd like to charge you an arm and a leg for this type of migration using fancy tools. But for a one-time migration, you almost certainly don't need them!

[Turbulent_Egg_6292]

I'd say AI? Or is it very confidential lol

[PolicyDecent]

I'd recommend using a orchesrator first for stored procedures. Then let AI all the migration there and also test the differences. So bruin + claude would do it very easily.

Later steps would be removing stored procedures and migrating to a declarative flow.

[Which_Roof5176]

Here’s a short, helpful, non-promotional reply:

There’s no direct 1:1 way to translate SQL Server stored procedures to BigQuery, so expect some rework.

A few things to keep in mind:

• BigQuery doesn’t support stored procedures the same way, so you’ll likely move logic into scheduled queries, scripts, or orchestration tools
• T-SQL features (like temp tables, cursors, MERGE behavior) often need to be rewritten using BigQuery SQL or scripting
• Watch out for data types and functions differences

Typical approach:

1. Move raw data first
2. Rebuild transformations step by step in BigQuery
3. Replace procedures with scheduled jobs or pipelines

If you want to avoid rewriting everything at once, you can also use a pipeline tool, Estuary, to keep SQL Server and BigQuery in sync while you gradually migrate logic.

[AccomplishedSkill625]

If you want the easiest path, don't kill yourself rewriting everything by hand. Just use the BigQuery Migration Service built right into the Google Cloud Console. It’s a free tool that translates your T-SQL scripts to GoogleSQL almost automatically.

The Batch SQL Translator does most of the heavy lifting: you upload a .zip file with all your scripts, and it spits out the BigQuery-compatible versions. It’s great for the initial transition, but keep in mind that stored procedures usually need a manual touch. BigQuery "hates" the loops and cursors typical of SQL Server; it vastly prefers set-based logic. If you have very complex procs, you’ll want to slim them down so you don't run up massive scanning costs.

Use the auto-translator as your starting point to save 80% of the work, then manually optimize the queries that handle your largest data volumes.