postgresql-8.0 | 易学教程

Optimized querying in PostgreSQL

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问题 Assume you have a table named tracker with following records. issue_id | ingest_date | verb,status 10 2015-01-24 00:00:00 1,1 10 2015-01-25 00:00:00 2,2 10 2015-01-26 00:00:00 2,3 10 2015-01-27 00:00:00 3,4 11 2015-01-10 00:00:00 1,3 11 2015-01-11 00:00:00 2,4 I need the following results 10 2015-01-26 00:00:00 2,3 11 2015-01-11 00:00:00 2,4 I am trying out this query select * from etl_change_fact where ingest_date = (select max(ingest_date) from etl_change_fact); However, this gives me only

REDSHIFT: How can I generate a series of numbers without creating a table called “numbers” in redshift (Postgres 8.0.2)?

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问题 I need to create an empty time table series for a report so I can left join activity from several tables to it. Every hour of the day does not necessarily have data, but I want it to show null or zero for inactivity instead of omitting that hour of the day. In later versions of Postgres (post 8.0.2), this is easy in several ways: SELECT unnest(array[0,1,2,3,4...]) as numbers OR CROSS JOIN (select generate_series as hours from generate_series(now()::timestamp, now()::timestamp + interval '1

REDSHIFT: How can I generate a series of numbers without creating a table called “numbers” in redshift (Postgres 8.0.2)?

阅读更多关于 REDSHIFT: How can I generate a series of numbers without creating a table called “numbers” in redshift (Postgres 8.0.2)?

I need to create an empty time table series for a report so I can left join activity from several tables to it. Every hour of the day does not necessarily have data, but I want it to show null or zero for inactivity instead of omitting that hour of the day. In later versions of Postgres (post 8.0.2), this is easy in several ways: SELECT unnest(array[0,1,2,3,4...]) as numbers OR CROSS JOIN (select generate_series as hours from generate_series(now()::timestamp, now()::timestamp + interval '1 day', '1 hour'::interval )) date_series Redshift can run some of these commands, but throws an error when