How do I create a dates table in Redshift?

Question

tl;dr: I want to generate a dates table in Redshift in order to make a report easier to generate. Preferable without needing large tables already in redshift, needing to up

Answer 1

In asking the question, I figured it out. Oops.

I started with a "facts" schema.

CREATE SCHEMA facts;

Run the following to start a numbers table:

create table facts.numbers
(
  number int PRIMARY KEY
)
;

Use this to generate your number list. I used a million to get started

SELECT ',(' || generate_series(0,1000000,1) || ')'
;

Then copy-paste the numbers from your results in the query below, after VALUES:

INSERT INTO facts.numbers
VALUES
 (0)
,(1)
,(2)
,(3)
,(4)
,(5)
,(6)
,(7)
,(8)
,(9)
-- etc

^ Make sure to remove the leading comma from the copy-pasted list of numbers

Once you have a numbers table, then you can generate a dates table (again, stealing code from elliot land http://elliot.land/post/building-a-date-dimension-table-in-redshift ) :

CREATE TABLE facts.dates (
  "date_id"              INTEGER                     NOT NULL PRIMARY KEY,

  -- DATE
  "full_date"            DATE                        NOT NULL,

  -- YEAR
  "year_number"          SMALLINT                    NOT NULL,
  "year_week_number"     SMALLINT                    NOT NULL,
  "year_day_number"      SMALLINT                    NOT NULL,

  -- QUARTER
  "qtr_number"           SMALLINT                    NOT NULL,

  -- MONTH
  "month_number"         SMALLINT                    NOT NULL,
  "month_name"           CHAR(9)                     NOT NULL,
  "month_day_number"     SMALLINT                    NOT NULL,

  -- WEEK
  "week_day_number"      SMALLINT                    NOT NULL,

  -- DAY
  "day_name"             CHAR(9)                     NOT NULL,
  "day_is_weekday"       SMALLINT                    NOT NULL,
  "day_is_last_of_month" SMALLINT                    NOT NULL
) DISTSTYLE ALL SORTKEY (date_id)
;


INSERT INTO facts.dates
(
   "date_id"
  ,"full_date"
  ,"year_number"
  ,"year_week_number"
  ,"year_day_number"

  -- QUARTER
  ,"qtr_number"

  -- MONTH
  ,"month_number"
  ,"month_name"
  ,"month_day_number"

  -- WEEK
  ,"week_day_number"

  -- DAY
  ,"day_name"
  ,"day_is_weekday"
  ,"day_is_last_of_month"
)
  SELECT
    cast(seq + 1 AS INTEGER)                                      AS date_id,

    -- DATE
    datum                                                         AS full_date,

    -- YEAR
    cast(extract(YEAR FROM datum) AS SMALLINT)                    AS year_number,
    cast(extract(WEEK FROM datum) AS SMALLINT)                    AS year_week_number,
    cast(extract(DOY FROM datum) AS SMALLINT)                     AS year_day_number,

    -- QUARTER
    cast(to_char(datum, 'Q') AS SMALLINT)                         AS qtr_number,

    -- MONTH
    cast(extract(MONTH FROM datum) AS SMALLINT)                   AS month_number,
    to_char(datum, 'Month')                                       AS month_name,
    cast(extract(DAY FROM datum) AS SMALLINT)                     AS month_day_number,

    -- WEEK
    cast(to_char(datum, 'D') AS SMALLINT)                         AS week_day_number,

    -- DAY
    to_char(datum, 'Day')                                         AS day_name,
    CASE WHEN to_char(datum, 'D') IN ('1', '7')
      THEN 0
    ELSE 1 END                                                    AS day_is_weekday,
    CASE WHEN
      extract(DAY FROM (datum + (1 - extract(DAY FROM datum)) :: INTEGER +
                        INTERVAL '1' MONTH) :: DATE -
                       INTERVAL '1' DAY) = extract(DAY FROM datum)
      THEN 1
    ELSE 0 END                                                    AS day_is_last_of_month
  FROM
    -- Generate days for 81 years starting from 2000.
    (
      SELECT
        '2000-01-01' :: DATE + number AS datum,
        number                        AS seq
      FROM facts.numbers
      WHERE number between 0 and 81 * 365 + 20
    ) DQ
  ORDER BY 1;

^ Be sure to set the numbers at the end for the date range you need