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MDEV-13049 Querying INFORMATION_SCHEMA becomes slow in MariaDB 10.1

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Optimizations:
* avoid faster ext_table_discovery_simple() *only* when there are
  engines with discover_table_names() method *and* they look at
  file names. P_S implements discover_table_names(), but it's not
  a reason to use slower extension_based_table_discovery().
* don't pre-sort table names if ORDER BY or GROUP BY was specified
* starting from 10.3 only sort table names for SHOW commands
This commit is contained in:
Sergei Golubchik
2017-10-06 18:16:46 +02:00
parent 559dec33cc
commit 9b11956e86
2 changed files with 17 additions and 9 deletions
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17
sql/handler.cc
View File

@ -405,7 +405,7 @@ static int ha_finish_errors(void)
} }
static volatile int32 need_full_discover_for_existence= 0; static volatile int32 need_full_discover_for_existence= 0;
static volatile int32 engines_with_discover_table_names= 0; static volatile int32 engines_with_discover_file_names= 0;
static volatile int32 engines_with_discover= 0; static volatile int32 engines_with_discover= 0;
static int full_discover_for_existence(handlerton *, const char *, const char *) static int full_discover_for_existence(handlerton *, const char *, const char *)
@ -430,8 +430,8 @@ static void update_discovery_counters(handlerton *hton, int val)
if (hton->discover_table_existence == full_discover_for_existence) if (hton->discover_table_existence == full_discover_for_existence)
my_atomic_add32(&need_full_discover_for_existence, val); my_atomic_add32(&need_full_discover_for_existence, val);
if (hton->discover_table_names) if (hton->discover_table_names && hton->tablefile_extensions[0])
my_atomic_add32(&engines_with_discover_table_names, val); my_atomic_add32(&engines_with_discover_file_names, val);
if (hton->discover_table) if (hton->discover_table)
my_atomic_add32(&engines_with_discover, val); my_atomic_add32(&engines_with_discover, val);
@ -5189,6 +5189,7 @@ void Discovered_table_list::remove_duplicates()
{ {
LEX_STRING **src= tables->front(); LEX_STRING **src= tables->front();
LEX_STRING **dst= src; LEX_STRING **dst= src;
sort();
while (++dst <= tables->back()) while (++dst <= tables->back())
{ {
LEX_STRING *s= *src, *d= *dst; LEX_STRING *s= *src, *d= *dst;
@ -5256,10 +5257,12 @@ int ha_discover_table_names(THD *thd, LEX_STRING *db, MY_DIR *dirp,
int error; int error;
DBUG_ENTER("ha_discover_table_names"); DBUG_ENTER("ha_discover_table_names");
if (engines_with_discover_table_names == 0 && !reusable) if (engines_with_discover_file_names == 0 && !reusable)
{ {
error= ext_table_discovery_simple(dirp, result); st_discover_names_args args= {db, NULL, result, 0};
result->sort(); error= ext_table_discovery_simple(dirp, result) ||
plugin_foreach(thd, discover_names,
MYSQL_STORAGE_ENGINE_PLUGIN, &args);
} }
else else
{ {
@ -5272,8 +5275,6 @@ int ha_discover_table_names(THD *thd, LEX_STRING *db, MY_DIR *dirp,
error= extension_based_table_discovery(dirp, reg_ext, result) || error= extension_based_table_discovery(dirp, reg_ext, result) ||
plugin_foreach(thd, discover_names, plugin_foreach(thd, discover_names,
MYSQL_STORAGE_ENGINE_PLUGIN, &args); MYSQL_STORAGE_ENGINE_PLUGIN, &args);
result->sort();
if (args.possible_duplicates > 0) if (args.possible_duplicates > 0)
result->remove_duplicates(); result->remove_duplicates();
} }

9
sql/sql_show.cc
View File

@ -979,13 +979,20 @@ find_files(THD *thd, Dynamic_array<LEX_STRING*> *files, LEX_STRING *db,
if (tl.add_file(file->name)) if (tl.add_file(file->name))
goto err; goto err;
} }
tl.sort();
} }
else else
{ {
if (ha_discover_table_names(thd, db, dirp, &tl, false)) if (ha_discover_table_names(thd, db, dirp, &tl, false))
goto err; goto err;
} }
#if MYSQL_VERSION_ID < 100300
/* incomplete optimization, but a less drastic change in GA version */
if (!thd->lex->select_lex.order_list.elements &&
!thd->lex->select_lex.group_list.elements)
#else
if (is_show_command(thd))
#endif
tl.sort();
DBUG_PRINT("info",("found: %zu files", files->elements())); DBUG_PRINT("info",("found: %zu files", files->elements()));
my_dirend(dirp); my_dirend(dirp);