How to choose the latest partition in BigQuery table?

Question

I am trying to select data from the latest partition in a date-partitioned BigQuery table, but the query still reads data from the whole table.

I\'ve tried (as far a

Answer 1

I found the workaround to this issue. You can use with statement, select last few partitions and filter out the result. This is I think better approach because:

1. You are not limited by fixed partition date (like today - 1 day). It will always take the latest partition from given range.
2. It will only scan last few partitions and not whole table.

Example with last 3 partitions scan:

WITH last_three_partitions as (select *, _PARTITIONTIME as PARTITIONTIME 
    FROM dataset.partitioned_table 
    WHERE  _PARTITIONTIME > TIMESTAMP_SUB(CURRENT_TIMESTAMP(), INTERVAL 3 DAY))
SELECT col1, PARTITIONTIME from last_three_partitions 
WHERE PARTITIONTIME = (SELECT max(PARTITIONTIME) from last_three_partitions)