[MDEV-28741] Disable query cache on Spider tables to avoid cache inconsistency Created: 2022-06-03  Updated: 2022-06-05  Resolved: 2022-06-05

Status: Closed
Project: MariaDB Server
Component/s: Storage Engine - Spider
Affects Version/s: None
Fix Version/s: N/A

Type: Bug Priority: Major
Reporter: Nayuta Yanagisawa (Inactive) Assignee: Nayuta Yanagisawa (Inactive)
Resolution: Won't Do Votes: 0
Labels: None


 Description   

If there are multiple (writable) Spider nodes, the content of the query cache of each node would be inconsistent. We simply disable the query cache on Spider tables to avoid inconsistency.

Setting thd->query_cache_is_applicable= 0 in ha_spider::register_query_cache_table() would fix the problem. To see how the function is used, check Query_cache::ask_handler_allowance().

 Comments   
Comment by Nayuta Yanagisawa (Inactive) [ 2022-06-05 ]

Already disabled by the following code:

uint8 ha_spider::table_cache_type()
 
{
 
  DBUG_ENTER("ha_spider::table_cache_type");
 
  DBUG_PRINT("info",("spider this=%p", this));
 
  DBUG_RETURN(HA_CACHE_TBL_NOCACHE);
 
}

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