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Fix for BUG#4177:

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* Make index merge quick selects code allow perform several scans.
 * Delay additional handler objects creation till row retrieval is started.


include/queues.h:
  Added trivial queue_remove_all macro
mysql-test/r/index_merge.result:
  Testcase for BUG#4177
mysql-test/t/index_merge.test:
  Testcase for BUG#4177
sql/opt_range.cc:
  Fix for BUG#4177: 
   * For any quick select, row retrieval can be performed several times. Now all index_merge quick selects code handles such cases properly.
   * In QUICK_INDEX_MERGE_SELECT we use one handler object for all merged scans, and it was possible that in 
      destructor several cleanup functions were called 
   * Additionally
    - Removed redundant QUICK_INDEX_MERGE_SELECT members.
    - Now QUICK_ROR_*_SELECTs create additional handler objects only when row retrieval is started
      So if join optimizer chooses other access method, we don't create/delete handlers.
This commit is contained in:
unknown
2004-11-21 11:51:19 +03:00
parent 6763a1da76
commit febda72f62
5 changed files with 188 additions and 47 deletions
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18
sql/opt_range.h
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@ -127,7 +127,8 @@ public:
reset() should be called when it is certain that row retrieval will be
necessary. This call may do heavyweight initialization like buffering first
N records etc. If reset() call fails get_next() must not be called.
Note that reset() may be called several times if this quick select
executes in a subselect.
RETURN
0 OK
other Error code
@ -274,6 +275,10 @@ public:
next=0;
range= NULL;
cur_range= NULL;
/*
Note: in opt_range.cc there are places where it is assumed that this
function always succeeds
*/
return 0;
}
int init();
@ -388,21 +393,15 @@ public:
/* range quick selects this index_merge read consists of */
List<QUICK_RANGE_SELECT> quick_selects;
/* quick select which is currently used for rows retrieval */
List_iterator_fast<QUICK_RANGE_SELECT> cur_quick_it;
QUICK_RANGE_SELECT* cur_quick_select;
/* quick select that uses clustered primary key (NULL if none) */
QUICK_RANGE_SELECT* pk_quick_select;
/* true if this select is currently doing a clustered PK scan */
bool doing_pk_scan;
Unique *unique;
MEM_ROOT alloc;
THD *thd;
int prepare_unique();
int read_keys_and_merge();
/* used to get rows collected in Unique */
READ_RECORD read_record;
@ -465,6 +464,8 @@ public:
MEM_ROOT alloc; /* Memory pool for this and merged quick selects data. */
THD *thd; /* current thread */
bool need_to_fetch_row; /* if true, do retrieve full table records. */
/* in top-level quick select, true if merged scans where initialized */
bool scans_inited;
};
@ -514,6 +515,7 @@ public:
uint rowid_length; /* table rowid length */
private:
static int queue_cmp(void *arg, byte *val1, byte *val2);
bool scans_inited;
};