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v5:userguide:learn_caching:cache_problems [2016/03/29 01:43] – created mnewnhamv5:userguide:learn_caching:cache_problems [2016/03/29 05:00] (current) – [Unexpected Results] mnewnham
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 ====== Solving Problems With Caching ====== ====== Solving Problems With Caching ======
 ===== Unexpected Results ===== ===== Unexpected Results =====
-Finding cached result sets is dependent on their being an **//exact//** query match on the SQL statement issued, so+Finding cached result sets is dependent on there being an **//exact//** query match on the SQL statement issued, so
 for example: for example:
   SELECT code,description FROM table ORDER BY code   SELECT code,description FROM table ORDER BY code
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   SELECT code,description FROM table ORDER BY code ASC   SELECT code,description FROM table ORDER BY code ASC
      
-Whilst the result set produced by the query in both queries would be exactly the same, because the checksum of the queries are different, they would not return the same cached query. The easiest way to avoid such errors is to define constants for cacheable queries and reuse them as such+Whilst the result set produced by the query in both queries would be exactly the same, because the checksums of the queries are different, they would not return the same cached query. The easiest way to avoid such errors is to define constants for queries and reuse them as such
 <code php> <code php>
 DEFINE ('CACHED_RESULT', 'SELECT code,description FROM table ORDER BY code ASC'); DEFINE ('CACHED_RESULT', 'SELECT code,description FROM table ORDER BY code ASC');
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 </code> </code>
 +-----------------------------------------------
 ===== Disk Based Caching ===== ===== Disk Based Caching =====
 The most common problem with using disk-based caching is the result of ownership permissions on the directories used for storing the cached result sets. Problems can be exacerbated under the following circumstances: The most common problem with using disk-based caching is the result of ownership permissions on the directories used for storing the cached result sets. Problems can be exacerbated under the following circumstances:
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   * Under IIS, use of multiple Application Pools with different identities   * Under IIS, use of multiple Application Pools with different identities
  
 +----------------------------------------------
 ===== Memcached Caching  ===== ===== Memcached Caching  =====
-The size of query results that can be cached by the memcached server is limited by server configuration. The default is quite small. If the query is too large, and [[v5:reference:debug|debugging]] is enabled, then an error is displayed.+The size of query results that can be cached by the memcached server is limited by server configuration. The default is quite small. If the query is too large, and [[v5:userguide:debug|debugging]] is enabled, then an error is displayed.
  
  
-  3849805e4e026b9e7c485999a24a95c6 cache failure: Item with such key doesn't exists on the memcached server.+  3849805e4e026b9e7c485999a24a95c6 cache failure: Item with such key 
 +  doesn't exists on the memcached server.
   (this is a notice and not an error)   (this is a notice and not an error)
   -----<hr>   -----<hr>
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   Cache write error   Cache write error
      
-  PHP Notice:  MemcachePool::set(): Server 192.168.0.78 (tcp 11211, udp 0) failed with: +  PHP Notice:  MemcachePool::set(): Server 192.168.0.78 (tcp 11211, udp 0 
-  SERVER_ERROR object too large for cache (3) +  ) failed with:  SERVER_ERROR object too large for cache (3) 
   in C:\dev\github\mssqlnative-fixes\adodb-memcache.lib.inc.php on line 94   in C:\dev\github\mssqlnative-fixes\adodb-memcache.lib.inc.php on line 94
      
v5/userguide/learn_caching/cache_problems.txt · Last modified: 2016/03/29 05:00 by mnewnham