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Small fixes and added comments to condition pushdown to ndbcluster, after code review

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2005-02-16 14:18:32 +01:00
parent 88a2b72ce0
commit 1acae43e43
3 changed files with 1073 additions and 977 deletions
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19
sql/handler.h
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@ -268,7 +268,7 @@ typedef struct st_table TABLE;
struct st_foreign_key_info;
typedef struct st_foreign_key_info FOREIGN_KEY_INFO;
/* Forward declaration for Condition Pushdown to Handler (CPDH) */
/* Forward declaration for condition pushdown to storage engine */
typedef struct Item COND;
typedef struct st_ha_check_opt
@ -625,7 +625,24 @@ public:
/*
Condition pushdown to storage engines
*/
/*
Push a condition to storage engine for evaluation during table
and index scans. The conditions should be stored on a stack
for possibly storing several conditions. The stack can be popped
by calling cond_pop, handler::extra(HA_EXTRA_RESET) (handler::reset())
should clear the stack.
The condition can be traversed using Item::traverse_cond
RETURN
NULL The condition was supported by the handler and will be evaluated
for each row found during the scan
cond The condition was not supported and all rows will be returned from
the scan for evaluation (and thus not saved on stack)
*/
virtual const COND *cond_push(const COND *cond) { return cond; };
/*
Pop the top condition from the condition stack of the handler instance.
*/
virtual void cond_pop() { return; };
};