Customized Customer Grid causing MySQL table scans and filesorts aka slow performance

Question

EDIT: I had this question originally posted on Stackoverflow that never got fully answered, I'm posting in here in hopes to shed anymore light on why the massive table scans and any means to prevent such with (hopefully) minimal core changes.

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Magento Enterprise. 1.10.1.1. The data set of customers and addresses are semi-large (125k+) CSRs are often on this grid (sometimes 25+ concurrent users at a time).

Here is the code snippet were the collection is being generated in the Customer Grid.php Block file. Nothing fancy or out of ordinary, simply adding attributes to the collection mainly.

$collection = Mage::getResourceModel('customer/customer_collection')
    ->addNameToSelect()
    ->addAttributeToSelect('email')
    ->addAttributeToSelect('group_id')
    ->addAttributeToSelect('prod_codes')
    ->addAttributeToSelect('last_called_date')
    ->addAttributeToSelect('time_zone')
    ->addAttributeToSelect('salesrep')
    ->addAttributeToSelect('do_not_call')
    ->addAttributeToSelect('club_member')
    ->addAttributeToSelect('call_back_date')
    ->addAttributeToSelect('marketing_code_outcome')
    ->joinAttribute('billing_postcode', 'customer_address/postcode', 'default_billing', null, 'left')
    ->joinAttribute('billing_city', 'customer_address/city', 'default_billing', null, 'left')
    ->joinAttribute('billing_telephone', 'customer_address/telephone', 'default_billing', null, 'left')
    ->joinAttribute('billing_region', 'customer_address/region', 'default_billing', null, 'left');

$this->setCollection($collection);

Generates this query, which is misbehaving causing very long load times while in the customer grid:

SELECT 
    e . *,
    _table_prefix.value AS prefix,
    _table_firstname.value AS firstname,
    _table_middlename.value AS middlename,
    _table_lastname.value AS lastname,
    _table_suffix.value AS suffix,
    CONCAT(IF(_table_prefix.value IS NOT NULL AND _table_prefix.value != '',
                CONCAT(TRIM(_table_prefix.value), ' '),
                ''),
            TRIM(_table_firstname.value),
            IF(_table_middlename.value IS NOT NULL AND _table_middlename.value != '',
                CONCAT(' ', TRIM(_table_middlename.value)),
                ''),
            ' ',
            TRIM(_table_lastname.value),
            IF(_table_suffix.value IS NOT NULL AND _table_suffix.value != '',
                CONCAT(' ', TRIM(_table_suffix.value)),
                '')) AS name,
    _table_default_billing.value AS default_billing,
    _table_billing_postcode.value AS billing_postcode,
    _table_billing_city.value AS billing_city,
    _table_billing_telephone.value AS billing_telephone,
    _table_billing_region.value AS billing_region
FROM
    customer_entity AS e
        LEFT JOIN
    customer_entity_varchar AS _table_prefix ON (_table_prefix.entity_id = e.entity_id) AND (_table_prefix.attribute_id = '4')
        LEFT JOIN
    customer_entity_varchar AS _table_firstname ON (_table_firstname.entity_id = e.entity_id) AND (_table_firstname.attribute_id = '5')
        LEFT JOIN
    customer_entity_varchar AS _table_middlename ON (_table_middlename.entity_id = e.entity_id) AND (_table_middlename.attribute_id = '6')
        LEFT JOIN
    customer_entity_varchar AS _table_lastname ON (_table_lastname.entity_id = e.entity_id) AND (_table_lastname.attribute_id = '7')
        LEFT JOIN
    customer_entity_varchar AS _table_suffix ON (_table_suffix.entity_id = e.entity_id) AND (_table_suffix.attribute_id = '8')
        LEFT JOIN
    customer_entity_int AS _table_default_billing ON (_table_default_billing.entity_id = e.entity_id) AND (_table_default_billing.attribute_id = '13')
        LEFT JOIN
    customer_address_entity_varchar AS _table_billing_postcode ON (_table_billing_postcode.entity_id = _table_default_billing.value) AND (_table_billing_postcode.attribute_id = '29')
        LEFT JOIN
    customer_address_entity_varchar AS _table_billing_city ON (_table_billing_city.entity_id = _table_default_billing.value) AND (_table_billing_city.attribute_id = '25')
        LEFT JOIN
    customer_address_entity_varchar AS _table_billing_telephone ON (_table_billing_telephone.entity_id = _table_default_billing.value) AND (_table_billing_telephone.attribute_id = '30')
        LEFT JOIN
    customer_address_entity_varchar AS _table_billing_region ON (_table_billing_region.entity_id = _table_default_billing.value) AND (_table_billing_region.attribute_id = '27')
WHERE
    (e.entity_type_id = '1')
ORDER BY CONCAT(IF(_table_prefix.value IS NOT NULL AND _table_prefix.value != '',
            CONCAT(TRIM(_table_prefix.value), ' '),
            ''),
        TRIM(_table_firstname.value),
        IF(_table_middlename.value IS NOT NULL AND _table_middlename.value != '',
            CONCAT(' ', TRIM(_table_middlename.value)),
            ''),
        ' ',
        TRIM(_table_lastname.value),
        IF(_table_suffix.value IS NOT NULL AND _table_suffix.value != '',
            CONCAT(' ', TRIM(_table_suffix.value)),
            '')) desc
LIMIT 20 OFFSET 60

an EXPLAIN on the query shows, NOTE the Extra on table e, Using temporary and Using filesort:

*************************** 1. row ***************************
           id: 1
  select_type: SIMPLE
        table: e
         type: ref
possible_keys: IDX_ENTITY_TYPE
          key: IDX_ENTITY_TYPE
      key_len: 2
          ref: const
         rows: 55556
        Extra: Using temporary; Using filesort
*************************** 2. row ***************************
           id: 1
  select_type: SIMPLE
        table: _table_prefix
         type: eq_ref
possible_keys: IDX_ATTRIBUTE_VALUE,FK_CUSTOMER_VARCHAR_ATTRIBUTE,FK_CUSTOMER_VARCHAR_ENTITY,IDX_VALUE
          key: IDX_ATTRIBUTE_VALUE
      key_len: 6
          ref: prod.e.entity_id,const
         rows: 1
        Extra:
*************************** 3. row ***************************
           id: 1
  select_type: SIMPLE
        table: _table_firstname
         type: eq_ref
possible_keys: IDX_ATTRIBUTE_VALUE,FK_CUSTOMER_VARCHAR_ATTRIBUTE,FK_CUSTOMER_VARCHAR_ENTITY,IDX_VALUE
          key: IDX_ATTRIBUTE_VALUE
      key_len: 6
          ref: prod.e.entity_id,const
         rows: 1
        Extra:
*************************** 4. row ***************************
           id: 1
  select_type: SIMPLE
        table: _table_middlename
         type: eq_ref
possible_keys: IDX_ATTRIBUTE_VALUE,FK_CUSTOMER_VARCHAR_ATTRIBUTE,FK_CUSTOMER_VARCHAR_ENTITY,IDX_VALUE
          key: IDX_ATTRIBUTE_VALUE
      key_len: 6
          ref: prod.e.entity_id,const
         rows: 1
        Extra:
*************************** 5. row ***************************
           id: 1
  select_type: SIMPLE
        table: _table_lastname
         type: eq_ref
possible_keys: IDX_ATTRIBUTE_VALUE,FK_CUSTOMER_VARCHAR_ATTRIBUTE,FK_CUSTOMER_VARCHAR_ENTITY,IDX_VALUE
          key: IDX_ATTRIBUTE_VALUE
      key_len: 6
          ref: prod.e.entity_id,const
         rows: 1
        Extra:
*************************** 6. row ***************************
           id: 1
  select_type: SIMPLE
        table: _table_suffix
         type: eq_ref
possible_keys: IDX_ATTRIBUTE_VALUE,FK_CUSTOMER_VARCHAR_ATTRIBUTE,FK_CUSTOMER_VARCHAR_ENTITY,IDX_VALUE
          key: IDX_ATTRIBUTE_VALUE
      key_len: 6
          ref: prod.e.entity_id,const
         rows: 1
        Extra:
*************************** 7. row ***************************
           id: 1
  select_type: SIMPLE
        table: _table_default_billing
         type: eq_ref
possible_keys: IDX_ATTRIBUTE_VALUE,FK_CUSTOMER_INT_ATTRIBUTE,FK_CUSTOMER_INT_ENTITY,IDX_VALUE
          key: IDX_ATTRIBUTE_VALUE
      key_len: 6
          ref: prod.e.entity_id,const
         rows: 1
        Extra:
*************************** 8. row ***************************
           id: 1
  select_type: SIMPLE
        table: _table_billing_postcode
         type: eq_ref
possible_keys: IDX_ATTRIBUTE_VALUE,FK_CUSTOMER_ADDRESS_VARCHAR_ATTRIBUTE,FK_CUSTOMER_ADDRESS_VARCHAR_ENTITY,IDX_VALUE
          key: IDX_ATTRIBUTE_VALUE
      key_len: 6
          ref: prod._table_default_billing.value,const
         rows: 1
        Extra:
*************************** 9. row ***************************
           id: 1
  select_type: SIMPLE
        table: _table_billing_city
         type: eq_ref
possible_keys: IDX_ATTRIBUTE_VALUE,FK_CUSTOMER_ADDRESS_VARCHAR_ATTRIBUTE,FK_CUSTOMER_ADDRESS_VARCHAR_ENTITY,IDX_VALUE
          key: IDX_ATTRIBUTE_VALUE
      key_len: 6
          ref: prod._table_default_billing.value,const
         rows: 1
        Extra:
*************************** 10. row ***************************
           id: 1
  select_type: SIMPLE
        table: _table_billing_telephone
         type: eq_ref
possible_keys: IDX_ATTRIBUTE_VALUE,FK_CUSTOMER_ADDRESS_VARCHAR_ATTRIBUTE,FK_CUSTOMER_ADDRESS_VARCHAR_ENTITY,IDX_VALUE
          key: IDX_ATTRIBUTE_VALUE
      key_len: 6
          ref: prod._table_default_billing.value,const
         rows: 1
        Extra:
*************************** 11. row ***************************
           id: 1
  select_type: SIMPLE
        table: _table_billing_region
         type: eq_ref
possible_keys: IDX_ATTRIBUTE_VALUE,FK_CUSTOMER_ADDRESS_VARCHAR_ATTRIBUTE,FK_CUSTOMER_ADDRESS_VARCHAR_ENTITY,IDX_VALUE
          key: IDX_ATTRIBUTE_VALUE
      key_len: 6
          ref: prod._table_default_billing.value,const
         rows: 1
        Extra:
11 rows in set (0.00 sec)

No indexes have been modified other than the default ones from Magento themselves for 1.10.1 See Structure of 1.5.1 (CE) here: http://www.magereverse.com/index/magento-sql-structure/version/1-5-1-0

Here is the alias table referred to AS e. on the scan:

CREATE TABLE `customer_entity` (
    `entity_id` INT(10) UNSIGNED NOT NULL AUTO_INCREMENT,
    `entity_type_id` SMALLINT(8) UNSIGNED NOT NULL DEFAULT '0',
    `attribute_set_id` SMALLINT(5) UNSIGNED NOT NULL DEFAULT '0',
    `website_id` SMALLINT(5) UNSIGNED NULL DEFAULT NULL,
    `email` VARCHAR(255) NOT NULL DEFAULT '',
    `group_id` SMALLINT(3) UNSIGNED NOT NULL DEFAULT '0',
    `increment_id` VARCHAR(50) NOT NULL DEFAULT '',
    `store_id` SMALLINT(5) UNSIGNED NULL DEFAULT '0',
    `created_at` DATETIME NOT NULL DEFAULT '0000-00-00 00:00:00',
    `updated_at` DATETIME NOT NULL DEFAULT '0000-00-00 00:00:00',
    `is_active` TINYINT(1) UNSIGNED NOT NULL DEFAULT '1',
    PRIMARY KEY (`entity_id`),
    INDEX `FK_CUSTOMER_ENTITY_STORE` (`store_id`),
    INDEX `IDX_ENTITY_TYPE` (`entity_type_id`),
    INDEX `IDX_AUTH` (`email`, `website_id`),
    INDEX `FK_CUSTOMER_WEBSITE` (`website_id`),
    CONSTRAINT `FK_CUSTOMER_ENTITY_STORE` FOREIGN KEY (`store_id`) REFERENCES `core_store` (`store_id`) ON UPDATE CASCADE ON DELETE SET NULL,
    CONSTRAINT `FK_CUSTOMER_WEBSITE` FOREIGN KEY (`website_id`) REFERENCES `core_website` (`website_id`) ON UPDATE CASCADE ON DELETE SET NULL
)

So the question is how can I get this query to perform better and not cause the temporary tables being created and scanned.

I'm not exactly sure what I can index to improve this queries performance, and I don't want to dig too much into modifying Magento's ORM.

Answer 1

The answer to your plight does not lie in the customizations, those are just fine. The problematic portion of the query is the ORDER BY and will only rear it's ugly head when the grid has been sorted by the Name column in the admin:

ORDER BY CONCAT(IF(_table_prefix.value IS NOT NULL AND _table_prefix.value != '',
        CONCAT(TRIM(_table_prefix.value), ' '),
        ''),
    TRIM(_table_firstname.value),
    IF(_table_middlename.value IS NOT NULL AND _table_middlename.value != '',
        CONCAT(' ', TRIM(_table_middlename.value)),
        ''),
    ' ',
    TRIM(_table_lastname.value),
    IF(_table_suffix.value IS NOT NULL AND _table_suffix.value != '',
        CONCAT(' ', TRIM(_table_suffix.value)),
        '')) DESC

This ORDER BY clause is needed to sort by the Name column because the Name column is a concatenation of the prefix, first, middle and last name of the customer. To combine the information and use it for ordering, a tmp table has to be used since the data being concatenated together is originating from the JOINs on the query. This is how the Magento core handles this sort, because it's merely applying the same code used in the WHERE clause to apply the sorts.

Wrapping the entire query as a sub-select would cut down the query time a bit, as it would not be using a temp table any more, but it would still be using filesort.

So there are two "solutions" that I can see here:

1. Create a full_name attribute on the customer entity which is populated on save. This pre-populated full_name attribute could then be used on the grid without any form of concatenation and would cut out the need for both the temp tables and the filesort.

2. Simply not sort by the Name column when time is an issue. This obviously won't help if you need to sort by Name, but something to keep in mind until you have the chance to build out the changes in #1 above. :)