MySQL Memory Size Validator

-- Set how much RAM (in GB) your server has
SET @total_ram_gb = 8;

-- Convert to bytes
SET @ram_bytes = @total_ram_gb * 1024 * 1024 * 1024;

-- Run the check
SELECT
    VARIABLE_NAME,
    VARIABLE_VALUE,
    CASE
        WHEN VARIABLE_NAME = 'innodb_buffer_pool_size' 
             AND VARIABLE_VALUE < @ram_bytes * 0.5
        THEN CONCAT('TOO LOW (Recommended: ', ROUND(@total_ram_gb * 0.5), 'G - ', ROUND(@total_ram_gb * 0.75), 'G)')
        
        WHEN VARIABLE_NAME = 'innodb_buffer_pool_size' 
             AND VARIABLE_VALUE >= @ram_bytes * 0.5
        THEN 'OK'

        WHEN VARIABLE_NAME = 'tmp_table_size' 
             AND VARIABLE_VALUE < 256 * 1024 * 1024
        THEN 'TOO LOW (Recommended: 256M - 512M)'

        WHEN VARIABLE_NAME = 'max_heap_table_size' 
             AND VARIABLE_VALUE < 256 * 1024 * 1024
        THEN 'TOO LOW (Recommended: 256M - 512M)'

        WHEN VARIABLE_NAME = 'query_cache_size' 
             AND VARIABLE_VALUE > 128 * 1024 * 1024
        THEN 'TOO HIGH (Recommended: 64M - 128M or DISABLE if using InnoDB)'

        ELSE 'OK'
    END AS Recommendation
FROM
    performance_schema.global_variables
WHERE
    VARIABLE_NAME IN (
        'innodb_buffer_pool_size',
        'tmp_table_size',
        'max_heap_table_size',
        'query_cache_size'
    );