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Avoid not needed renames in ALTER TABLE

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Removed not needed table renames when doing ALTER TABLE when engine
changes and both of the following is true:
- Either new or old engine does not store the table in files
- Neither old or new engine uses files from another engine

We also skip renames when ALTER TABLE does an explicit rename

This improves performance, especially for engines where rename is
a slow operation (like the upcoming S3 engine)
This commit is contained in:
Monty
2019-05-08 23:39:29 +03:00
parent 10e8ba13c6
commit 043a3a0176
5 changed files with 96 additions and 26 deletions
Download Patch File Download Diff File Expand all files Collapse all files

111
sql/sql_table.cc
View File

@ -2734,7 +2734,8 @@ bool log_drop_table(THD *thd, const LEX_CSTRING *db_name,
*/
bool quick_rm_table(THD *thd, handlerton *base, const LEX_CSTRING *db,
const LEX_CSTRING *table_name, uint flags, const char *table_path)
const LEX_CSTRING *table_name, uint flags,
const char *table_path)
{
char path[FN_REFLEN + 1];
int error= 0;
@ -2742,11 +2743,13 @@ bool quick_rm_table(THD *thd, handlerton *base, const LEX_CSTRING *db,
size_t path_length= table_path ?
(strxnmov(path, sizeof(path) - 1, table_path, reg_ext, NullS) - path) :
build_table_filename(path, sizeof(path)-1, db->str, table_name->str, reg_ext, flags);
if (mysql_file_delete(key_file_frm, path, MYF(0)))
error= 1; /* purecov: inspected */
build_table_filename(path, sizeof(path)-1, db->str, table_name->str,
reg_ext, flags);
if (!(flags & NO_FRM_RENAME))
if (mysql_file_delete(key_file_frm, path, MYF(0)))
error= 1; /* purecov: inspected */
path[path_length - reg_ext_length]= '\0'; // Remove reg_ext
if (flags & NO_HA_TABLE)
if ((flags & (NO_HA_TABLE | NO_PAR_TABLE)) == NO_HA_TABLE)
{
handler *file= get_new_handler((TABLE_SHARE*) 0, thd->mem_root, base);
if (!file)
@ -5509,7 +5512,8 @@ mysql_rename_table(handlerton *base, const LEX_CSTRING *old_db,
{
if (rename_file_ext(from,to,reg_ext))
error= my_errno;
(void) file->ha_create_partitioning_metadata(to, from, CHF_RENAME_FLAG);
if (!(flags & NO_PAR_TABLE))
(void) file->ha_create_partitioning_metadata(to, from, CHF_RENAME_FLAG);
}
else if (!file || likely(!(error=file->ha_rename_table(from_base, to_base))))
{
@ -9251,6 +9255,7 @@ bool mysql_alter_table(THD *thd, const LEX_CSTRING *new_db,
Alter_info *alter_info,
uint order_num, ORDER *order, bool ignore)
{
bool engine_changed;
DBUG_ENTER("mysql_alter_table");
/*
@ -10177,6 +10182,23 @@ do_continue:;
goto end_temporary;
}
/*
Check if file names for the engine are unique. If we change engine
and file names are unique then we don't need to rename the original
table to a temporary name during the rename phase
File names are unique if engine changed and
- Either new or old engine does not store the table in files
- Neither old or new engine uses files from another engine
The above is mainly true for the sequence and the partition engine.
*/
engine_changed= ((new_table->file->ht != table->file->ht) &&
(((!(new_table->file->ha_table_flags() & HA_FILE_BASED) ||
!(table->file->ha_table_flags() & HA_FILE_BASED))) ||
(!(table->file->ha_table_flags() & HA_REUSES_FILE_NAMES) &&
!(new_table->file->ha_table_flags() &
HA_REUSES_FILE_NAMES))));
/*
Close the intermediate table that will be the new table, but do
not delete it! Even though MERGE tables do not have their children
@ -10220,23 +10242,39 @@ do_continue:;
/*
Rename the old table to temporary name to have a backup in case
anything goes wrong while renaming the new table.
We only have to do this if name of the table is not changed.
If we are changing to use another table handler, we don't
have to do the rename as the table names will not interfer.
*/
char backup_name_buff[FN_LEN];
LEX_CSTRING backup_name;
backup_name.str= backup_name_buff;
backup_name.length= my_snprintf(backup_name_buff, sizeof(backup_name_buff),
"%s2-%lx-%lx", tmp_file_prefix,
current_pid, (long) thd->thread_id);
if (lower_case_table_names)
my_casedn_str(files_charset_info, backup_name_buff);
if (mysql_rename_table(old_db_type, &alter_ctx.db, &alter_ctx.table_name,
&alter_ctx.db, &backup_name, FN_TO_IS_TMP))
DBUG_PRINT("info", ("is_table_renamed: %d engine_changed: %d",
alter_ctx.is_table_renamed(), engine_changed));
if (!alter_ctx.is_table_renamed())
{
// Rename to temporary name failed, delete the new table, abort ALTER.
(void) quick_rm_table(thd, new_db_type, &alter_ctx.new_db,
&alter_ctx.tmp_name, FN_IS_TMP);
goto err_with_mdl;
backup_name.length= my_snprintf(backup_name_buff, sizeof(backup_name_buff),
"%s2-%lx-%lx", tmp_file_prefix,
current_pid, (long) thd->thread_id);
if (lower_case_table_names)
my_casedn_str(files_charset_info, backup_name_buff);
if (mysql_rename_table(old_db_type, &alter_ctx.db, &alter_ctx.table_name,
&alter_ctx.db, &backup_name,
FN_TO_IS_TMP |
(engine_changed ? NO_HA_TABLE | NO_PAR_TABLE : 0)))
{
// Rename to temporary name failed, delete the new table, abort ALTER.
(void) quick_rm_table(thd, new_db_type, &alter_ctx.new_db,
&alter_ctx.tmp_name, FN_IS_TMP);
goto err_with_mdl;
}
}
else
{
/* The original table is the backup */
backup_name= alter_ctx.table_name;
}
// Rename the new table to the correct name.
@ -10248,10 +10286,15 @@ do_continue:;
(void) quick_rm_table(thd, new_db_type, &alter_ctx.new_db,
&alter_ctx.tmp_name, FN_IS_TMP);
// Restore the backup of the original table to the old name.
(void) mysql_rename_table(old_db_type, &alter_ctx.db, &backup_name,
&alter_ctx.db, &alter_ctx.alias,
FN_FROM_IS_TMP | NO_FK_CHECKS);
if (!alter_ctx.is_table_renamed())
{
// Restore the backup of the original table to the old name.
(void) mysql_rename_table(old_db_type, &alter_ctx.db, &backup_name,
&alter_ctx.db, &alter_ctx.alias,
FN_FROM_IS_TMP | NO_FK_CHECKS |
(engine_changed ? NO_HA_TABLE | NO_PAR_TABLE :
0));
}
goto err_with_mdl;
}
@ -10271,7 +10314,9 @@ do_continue:;
// Restore the backup of the original table to the old name.
(void) mysql_rename_table(old_db_type, &alter_ctx.db, &backup_name,
&alter_ctx.db, &alter_ctx.alias,
FN_FROM_IS_TMP | NO_FK_CHECKS);
FN_FROM_IS_TMP | NO_FK_CHECKS |
(engine_changed ? NO_HA_TABLE | NO_PAR_TABLE :
0));
goto err_with_mdl;
}
rename_table_in_stat_tables(thd, &alter_ctx.db, &alter_ctx.alias,
@ -10279,7 +10324,19 @@ do_continue:;
}
// ALTER TABLE succeeded, delete the backup of the old table.
if (quick_rm_table(thd, old_db_type, &alter_ctx.db, &backup_name, FN_IS_TMP))
error= quick_rm_table(thd, old_db_type, &alter_ctx.db, &backup_name,
FN_IS_TMP |
(engine_changed ? NO_HA_TABLE | NO_PAR_TABLE: 0));
if (engine_changed)
{
/* the .frm file was removed but not the original table */
error|= quick_rm_table(thd, old_db_type, &alter_ctx.db,
&alter_ctx.table_name,
NO_FRM_RENAME |
(engine_changed ? 0 : FN_IS_TMP));
}
if (error)
{
/*
The fact that deletion of the backup failed is not critical
@ -10325,6 +10382,7 @@ end_temporary:
DBUG_RETURN(false);
err_new_table_cleanup:
DBUG_PRINT("error", ("err_new_table_cleanup"));
my_free(const_cast<uchar*>(frm.str));
/*
No default value was provided for a DATE/DATETIME field, the
@ -10374,11 +10432,16 @@ err_new_table_cleanup:
DBUG_RETURN(true);
err_with_mdl_after_alter:
DBUG_PRINT("error", ("err_with_mdl_after_alter"));
/* the table was altered. binlog the operation */
DBUG_ASSERT(!(mysql_bin_log.is_open() &&
thd->is_current_stmt_binlog_format_row() &&
(create_info->tmp_table())));
write_bin_log(thd, true, thd->query(), thd->query_length());
/*
We can't reset error as we will return 'true' below and the server
expects that error is set
*/
write_bin_log(thd, FALSE, thd->query(), thd->query_length());
err_with_mdl:
/*