Reducing DB calls for high traffic site when cached

Hello,

We have created a websitein modx that should receive 25k visitors a day.

We have an array of PHP servers but 1 mysql server. So we need to ensure that all calls to the db are cached.

What I have tried with modx.
1) Turned on cache_db in systems settings
Results: "Most of the db calls" are cached.
Looking at the mysql query log, there are still calls to the modx_session table and calls to modx_access_resources_groups.

2) To remove the session db calls.
Turned on system settings -> Enable database session cache.
Result: I see that the session related queries are gone. Good

3) Remaining uncached db queries.
My mysql log still outputs a list of queries. So not all the db queries are cached.

For example:
The 8 queries are always made, each return empty result set.

SELECT Acl.target, Acl.principal, Acl.authority, Acl.policy, Policy.data FROM `modx_access_resource_groups` Acl LEFT JOIN `modx_access_policies` Policy ON Policy.id = Acl.policy JOIN `modx_document_groups` ResourceGroup ON Acl.principal_class = 'modUserGroup' AND (Acl.context_key = 'web' OR Acl.context_key IS NULL OR Acl.context_key = '') AND ResourceGroup.document = '1' AND ResourceGroup.document_group = Acl.target GROUP BY Acl.target, Acl.principal, Acl.authority, Acl.policy

SELECT Acl.target, Acl.principal, Acl.authority, Acl.policy, Policy.data FROM `modx_access_resource_groups` Acl LEFT JOIN `modx_access_policies` Policy ON Policy.id = Acl.policy JOIN `modx_document_groups` ResourceGroup ON Acl.principal_class = 'modUserGroup' AND (Acl.context_key = 'web' OR Acl.context_key IS NULL OR Acl.context_key = '') AND ResourceGroup.document = '1' AND ResourceGroup.document_group = Acl.target GROUP BY Acl.target, Acl.principal, Acl.authority, Acl.policy

SELECT Acl.target, Acl.principal, Acl.authority, Acl.policy, Policy.data FROM `modx_access_resource_groups` Acl LEFT JOIN `modx_access_policies` Policy ON Policy.id = Acl.policy JOIN `modx_document_groups` ResourceGroup ON Acl.principal_class = 'modUserGroup' AND (Acl.context_key = 'web' OR Acl.context_key IS NULL OR Acl.context_key = '') AND ResourceGroup.document = '64' AND ResourceGroup.document_group = Acl.target GROUP BY Acl.target, Acl.principal, Acl.authority, Acl.policy

SELECT Acl.target, Acl.principal, Acl.authority, Acl.policy, Policy.data FROM `modx_access_resource_groups` Acl LEFT JOIN `modx_access_policies` Policy ON Policy.id = Acl.policy JOIN `modx_site_tmplvar_access` ResourceGroup ON Acl.principal_class = 'modUserGroup' AND (Acl.context_key = 'web' OR Acl.context_key IS NULL OR Acl.context_key = '') AND ResourceGroup.tmplvarid = '123' AND ResourceGroup.documentgroup = acl.target ORDER BY Acl.target, Acl.principal, Acl.authority

SELECT Acl.target, Acl.principal, Acl.authority, Acl.policy, Policy.data FROM `modx_access_category` Acl LEFT JOIN `modx_access_policies` Policy ON Policy.id = Acl.policy JOIN `modx_categories_closure` CategoryClosure ON CategoryClosure.descendant = '13' AND Acl.principal_class = 'modUserGroup' AND CategoryClosure.ancestor = Acl.target AND (Acl.context_key = 'web' OR Acl.context_key IS NULL OR Acl.context_key = '') ORDER BY CategoryClosure.depth DESC, target, principal, authority ASC

SELECT Acl.target, Acl.principal, Acl.authority, Acl.policy, Policy.data FROM `modx_access_resource_groups` Acl LEFT JOIN `modx_access_policies` Policy ON Policy.id = Acl.policy JOIN `modx_site_tmplvar_access` ResourceGroup ON Acl.principal_class = 'modUserGroup' AND (Acl.context_key = 'web' OR Acl.context_key IS NULL OR Acl.context_key = '') AND ResourceGroup.tmplvarid = '52' AND ResourceGroup.documentgroup = acl.target ORDER BY Acl.target, Acl.principal, Acl.authority

SELECT Acl.target, Acl.principal, Acl.authority, Acl.policy, Policy.data FROM `modx_access_category` Acl LEFT JOIN `modx_access_policies` Policy ON Policy.id = Acl.policy JOIN `modx_categories_closure` CategoryClosure ON CategoryClosure.descendant = '13' AND Acl.principal_class = 'modUserGroup' AND CategoryClosure.ancestor = Acl.target AND (Acl.context_key = 'web' OR Acl.context_key IS NULL OR Acl.context_key = '') ORDER BY CategoryClosure.depth DESC, target, principal, authority ASC

SELECT Acl.target, Acl.principal, Acl.authority, Acl.policy, Policy.data FROM `modx_access_resource_groups` Acl LEFT JOIN `modx_access_policies` Policy ON Policy.id = Acl.policy JOIN `modx_document_groups` ResourceGroup ON Acl.principal_class = 'modUserGroup' AND (Acl.context_key = 'web' OR Acl.context_key IS NULL OR Acl.context_key = '') AND ResourceGroup.document = '1' AND ResourceGroup.document_group = Acl.target GROUP BY Acl.target, Acl.principal, Acl.authority, Acl.policy


Is there any way that I can completly prevent DB query for a period of time once the cache is primed.

Any advice appreciated.

Thanks
Jim

If you are not using Resource Group or Element Category access controls in your web Context, add the following Context Settings to disable these checks altogether...

access_category_enabled = 0
access_resource_group_enabled = 0

Or edit the System Settings for these to disabled those checks across all Contexts (if you do not use Resource Group or Category permissions anywhere).

I have also found http://modx.com/extras/package/getcache helps a lot on DB intensive snippets.