I'm using C# to dynamically construct a query based on a response from the bigquery api tables endpoint. I'm trying to calculate active users which works, but only if I select every table with .*. My question is quite simple really, is there a way to check if a table exists within BigQuery SQL?
There are metatables called __TABLES__ and __TABLES_SUMMARY__
You can run a query like:
SELECT size_bytes FROM <dataset>.__TABLES__ WHERE table_id='mytablename'
The __TABLES__ portion of that query may look unfamiliar. __TABLES_SUMMARY__ is a meta-table containing information about tables in a dataset. You can use this meta-table yourself. For example, the query SELECT * FROM publicdata:samples.__TABLES_SUMMARY__ will return metadata about the tables in the publicdata:samples dataset. You can also do SELECT * FROM publicdata:samples.__TABLES__
Available Fields:
The fields of the __TABLES_SUMMARY__ meta-table (that are all available in the TABLE_QUERY query) include:
table_id: name of the table.creation_time: time, in milliseconds since 1/1/1970 UTC, that the table was created. This is the same as the creation_time field on the table.type: whether it is a view (2) or regular table (1).The following fields are not available in TABLE_QUERY() since they are members of __TABLES__ but not __TABLES_SUMMARY__. They're kept here for historical interest and to partially document the __TABLES__ metatable:
last_modified_time: time, in milliseconds since 1/1/1970 UTC, that the table was updated (either metadata or table contents). Note that if you use the tabledata.insertAll() to stream records to your table, this might be a few minutes out of date.row_count: number of rows in the table.size_bytes: total size in bytes of the table.