[Solved] SQLite - Prevent a slow CTE being evaulated multiple times

How to optimize this SQL query?

In case you have your own slow SQL query, you can optimize it automatically here.

For the query above, the following recommendations will be helpful as part of the SQL tuning process.
You'll find 3 sections below:

  1. Description of the steps you can take to speed up the query.
  2. The optimal indexes for this query, which you can copy and create in your database.
  3. An automatically re-written query you can copy and execute in your database.
The optimization process and recommendations:
  1. Use UNION ALL instead of UNION (query line: 31): Always use UNION ALL unless you need to eliminate duplicate records. By using UNION ALL, you'll avoid the expensive distinct operation the database applies when using a UNION clause.
The optimized query:
WITH RECURSIVE large_table (x, y, z) AS (
VALUES
    (0, 0, 0) 
UNION
ALL SELECT
    large_table.x + 1,
    'Y' 
    OR (large_table.x + 1),
    'Z' 
    OR (large_table.x + 1) 
FROM
    large_table 
WHERE
    large_table.x < 500000), slow_cte (x, y, z) AS (SELECT
    large_table.x,
    large_table.y,
    large_table.z 
FROM
    large_table 
WHERE
    large_table.x % 100000 = 1) SELECT
    slow_cte.x 
FROM
    slow_cte 
UNION
SELECT
    slow_cte.y 
FROM
    slow_cte 
UNION
SELECT
    slow_cte.z 
FROM
    slow_cte

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* original question posted on StackOverflow here.