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MDEV-7964 - delete_dynamic() takes 0.12% in OLTP RO

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delete_dynamic() was called 9-11x per OLTP RO query + 3x per BEGIN/COMMIT.

3 calls were performed by LEX_MASTER_INFO. Added condition to call those only
for CHANGE MASTER.

1 call was performed by lock_table_names()/Hash_set/my_hash_free(). Hash_set was
supposed to be used for DDL and LOCK TABLES to gather database names, while it
was initialized/freed for DML too. In fact Hash_set didn't do any useful job
here. Hash_set was removed and MDL requests are now added directly to the list.

The rest 5-7 calls are done by optimizer, mostly by Explain_query and friends.
Since dynamic arrays are used in most cases, they can hardly be optimized.

my_hash_free() overhead dropped 0.02 -> out of radar.
delete_dynamic() overhead dropped 0.12 -> 0.04.
This commit is contained in:
Sergey Vojtovich 2015-04-16 18:38:26 +04:00
commit c4d2c4e844
3 changed files with 20 additions and 32 deletions
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13
sql/sql_lex.h
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@ -260,12 +260,15 @@ struct LEX_MASTER_INFO
my_init_dynamic_array(&repl_ignore_domain_ids,
sizeof(ulong), 0, 16, MYF(0));
}
void reset()
void reset(bool is_change_master)
{
delete_dynamic(&repl_ignore_server_ids);
/* Free all the array elements. */
delete_dynamic(&repl_do_domain_ids);
delete_dynamic(&repl_ignore_domain_ids);
if (unlikely(is_change_master))
{
delete_dynamic(&repl_ignore_server_ids);
/* Free all the array elements. */
delete_dynamic(&repl_do_domain_ids);
delete_dynamic(&repl_ignore_domain_ids);
}
host= user= password= log_file_name= ssl_key= ssl_cert= ssl_ca=
ssl_capath= ssl_cipher= relay_log_name= 0;