[Solved] PostgreSQL hstore: improve LIKE performance with index?

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. Avoid OR Conditions By Using UNION (modified query below): In mosts cases, filtering using the OR operator cannot be applied using indexes. A more optimized alternative will be to split the query to two parts combined with a UNION clause, while each query holds one part of the original OR condition.
  2. Use UNION ALL instead of UNION (query line: 24): 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:
SELECT
        a,
        b,
        c 
    FROM
        ((SELECT
            table.hstore->'a' AS a,
            table.hstore->'b' AS b,
            table.hstore->'c' AS c 
        FROM
            table 
        WHERE
            table.hstore->'z' ILIKE '123%') 
    UNION
    DISTINCT (SELECT
        table.hstore->'a' AS a,
        table.hstore->'b' AS b,
        table.hstore->'c' AS c 
    FROM
        table 
    WHERE
        table.hstore->'y' ILIKE '123%') 
UNION
DISTINCT (SELECT
    table.hstore->'a' AS a,
    table.hstore->'b' AS b,
    table.hstore->'c' AS c 
FROM
    table 
WHERE
    table.hstore->'x' ILIKE '123%')
) AS union1

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* original question posted on StackOverflow here.