BigQuery - Check if table already exists

Here is a python snippet that will tell whether a table exists (deleting it in the process--careful!):

def doesTableExist(project_id, dataset_id, table_id):
  bq.tables().delete(
      projectId=project_id, 
      datasetId=dataset_id,
      tableId=table_id).execute()
  return False

Alternately, if you'd prefer not deleting the table in the process, you could try:

def doesTableExist(project_id, dataset_id, table_id):
  try:
    bq.tables().get(
        projectId=project_id, 
        datasetId=dataset_id,
        tableId=table_id).execute()
    return True
  except HttpError, err
    if err.resp.status <> 404:
       raise
    return False

If you want to know where bq came from, you can call build_bq_client from here: http://code.google.com/p/bigquery-e2e/source/browse/samples/ch12/auth.py

In general, if you're using this to test whether you should run a job that will modify the table, it can be a good idea to just do the job anyway, and use WRITE_TRUNCATE as a write disposition.

Another approach can be to create a predictable job id, and retry the job with that id. If the job already exists, the job already ran (you might want to double check to make sure the job didn't fail, however).

Alex F's solution works on v0.27, but will not work on later versions. In order to migrate to v0.28+, the below solution will work.

from google.cloud import bigquery

project_nm = 'gc_project_nm'
dataset_nm = 'ds_nm'
table_nm = 'tbl_nm'

client = bigquery.Client(project_nm)
dataset = client.dataset(dataset_nm)
table_ref = dataset.table(table_nm)

def if_tbl_exists(client, table_ref):
    from google.cloud.exceptions import NotFound
    try:
        client.get_table(table_ref)
        return True
    except NotFound:
        return False

if_tbl_exists(client, table_ref)