如何在大查询中的现有表上创建分区和集群？

Question

In SQL Server, we can create index like this. How do we create the index after the table already exists? What is the syntax of create clusted index in bigquery?

CREATE INDEX abcd ON `abcd.xxx.xxx`(columnname )

In big query, we can create table like below. But how to create partition and cluster on an existing table?

CREATE TABLE rep_sales.orders_tmp PARTITION BY DATE(created_at) CLUSTER BY created_at AS SELECT * FROM rep_sales.orders

Answer 1

As @Sergey Geron mentioned in the comments, BigQuery doesn't support indexes. For more information, please refer to this doc .

An existing table cannot be partitioned but you can create a new partitioned table and then load the data into it from the unpartitioned table.

As for clustering of tables, BigQuery supports changing an existing non-clustered table to a clustered table and vice versa. You can also update the set of clustered columns of a clustered table. This method of updating the clustering column set is useful for tables that use continuous streaming inserts because those tables cannot be easily swapped by other methods.

You can change the clustering specification in the following ways:

• Call the tables.update or tables.patch API method.

• Call the bq command-line tool's bq update command with the --clustering_fields flag.

Note: When a table is converted from non-clustered to clustered or the clustered column set is changed, automatic re-clustering only works from that time onward. For example, a non-clustered 1 PB table that is converted to a clustered table using tables.update still has 1 PB of non-clustered data. Automatic re-clustering only applies to any new data committed to the table after the update.