bigquery: Temporary table support

[prochac]

BigQuery SDK should support temporary tables. The same temp table as it can be created by following query, if SQL method is used:

CREATE TEMPORARY TABLE foo ( ... )

https://cloud.google.com/bigquery/docs/reference/standard-sql/data-definition-language#create_table_statement

But by SDK documentation we should create table with expiration time.
https://pkg.go.dev/cloud.google.com/go/bigquery#hdr-Datasets_and_Tables
That's the only part mentioning temporary tables.
But It is an old way to do it, since 2019, when CREATE TEMP TABLE was introduced.

I think it should be as a parameter for
https://pkg.go.dev/cloud.google.com/go/bigquery#Table.Create
, so part of
https://pkg.go.dev/cloud.google.com/go/bigquery#TableMetadata

Or am I missing something?

[shollyman]

I suppose it comes down to what you're doing with the temporary table. If you're just wanting to do multi-statement queries, it's perfectly reasonable to supply SQL text for execution that's effectively a CREATE TEMPORARY TABLE foo AS ....; SELECT blah FROM foo;

If you want to issue multiple queries over time and not in the same script block, what you'll want to do is bind the statements to a session. This capability was recently added via #4754.

If your use case falls outside those patterns, perhaps you could describe what your intent is in a bit more detail?

[prochac]

We use temp table to run merge query to final table

MERGE the_table T USING temp_table S ON T.col = S.col WHEN NOT MATCHED THEN INSERT ...

Currently, we create a regular table for it.

[shollyman]

I'm still not sure what you're requesting.

A temporary table is ephemeral, and exists either for the lifetime of a single query job (or a query session). It doesn't really make sense to create the temp table programmatically the same way you would a managed table by invoking table.Create() for example, as that's outside the scope of a query.

What are you envisioning that you would do with a temp table created via the the library rather than SQL?

[shollyman]

Closing this, as there's been no further interaction. If you have more details, feel free to comment and we can reopen this issue.