从多个数据集中获取日期

Question

I am trying to get the list of tables and their last_modified_date using bigquery. using below code i can get the last modified time from one dataset. But i want to know how to get the last modified data from multiple dataset

query = """SELECT 
  dataset_id,
  table_id,
  -- Convert UNIX EPOCH to a timestamp.
  TIMESTAMP_MILLIS(creation_time) AS creation_time,
  TIMESTAMP_MILLIS(last_modified_time) as last_modified_time
FROM
  `project.dataset.__TABLES__`;"""

Answer 1

To expand the scope of what tables returned use the following to grab all the tables within the project for the provided region (example for us region):

SELECT 
  dataset_id,
  table_id,
  -- Convert UNIX EPOCH to a timestamp.
  TIMESTAMP_MILLIS(creation_time) AS creation_time,
  TIMESTAMP_MILLIS(last_modified_time) as last_modified_time
FROM
project.`region-us`.INFORMATION_SCHEMA.TABLES

For more documentation see here: https://cloud.google.com/bigquery/docs/information-schema-tables#scope_and_syntax

Answer 2

To find metadata of the dataset you need to call INFORMATION_SCHEMA.SCHEMATA and find the metadata of table INFORMATION_SCHEMA.TABLES .

For example:

SELECT
t2.table_schema,
t2.table_name,
t2.creation_time,
t1.last_modified_time
FROM
region-us.INFORMATION_SCHEMA.SCHEMATA t1
INNER JOIN
region-us.INFORMATION_SCHEMA.TABLES t2
ON
t1.schema_name=t2.table_schema;