![]() #sql9a0_7_c.frm # This is the MEMORY engine file. InnoDB tables are also portable between systems to systems similar to MyISAM. The InnoDB tables also provide optimal performance. It is the first table type that supports foreign keys. The value in the Support column indicates whether an engine can be used. The InnoDB tables in MySQL fully support transaction-safe storage engine with ACID-compliant. To determine which storage engines your server supports, use the SHOW ENGINES statement. #sql9a0_7_d.MYI # MyISAM index file for temporary table. MySQL Server uses a pluggable storage engine architecture that enables storage engines to be loaded into and unloaded from a running MySQL server. Those two specific engines you asked about (InnoDB and MyISAM) have different design goals. #sql9a0_7_d.MYD # MyISAM data file for temporary table. With MyISAM, a DML statement will obtain an exclusive lock on the table, and while that lock is held, no other session can perform a SELECT or a DML operation on the table. #sql9a0_7_d.frm # This is the MyISAM temporary table. The temporary tables are stored in C:\Windows\Temp and have unusual names, but internally the data is stored in the same way. Table_m # No MYD or MYI file for the MEMORY engine. Table_innodb.MYI # MyISAM table index file. Table_innodb.MYD # MyISAM table data file. I then checked the directory: C:\ProgramData\MySQL\MySQL Server 5.5\data\test (on Windows) and the files present were: After running the following commands: CREATE TABLE test.table_myisam (x int) ENGINE=MyISAM ĬREATE TABLE test.table_memory (x int) ENGINE=MEMORY ĬREATE TEMPORARY TABLE test.temp_table_myisam (x int) ENGINE=MyISAM ĬREATE TEMPORARY TABLE test.temp_table_memory (x int) ENGINE=MEMORY It should be possible to actually find the files that are created in the filesystem when the temporary tables are created. If you specify the MEMORY engine, the data will only be stored in memory. By default the table data will be stored on disk. If you wish to test this manually, you can make a temp table, add all the indexes to the empty temp table, disable indexes, insert the data, enable indexes, and switch table names.It depends on what engine you specify. Note also that (a) this bug was originally reported in Cluster/6.3 nearly three years ago (b) a fix has been available for over a year now (c) this fix is still not available in the product where it was originally reported. You can disable the building of non-unique indexes so that sorting and be done.ĭoing so can make a smaller BTREE for each index ALTER TABLE mytable DISABLE KEYS Setting back to open and asking that this fix along with fix for BUG31110 be merged to Cluster. Only the InnoDB and MyISAM storage engines support indexing on BLOB and TEXT columns. You should create all 11 indexes in a single DDL statement ALTER TABLE myisamtable I would like to suggest the following SUGGESTION #1 : Build all 11 indexes at the same time I suspect your must be just doing the following: ALTER TABLE mytable ADD INDEX (column01) ĪLTER TABLE mytable ADD INDEX (column02) ĪLTER TABLE mytable ADD INDEX (column03) ĪLTER TABLE mytable ADD INDEX (column10) ĪLTER TABLE mytable ADD INDEX (column11) Without any additional details from you, I can only guess. ![]() : Does MySQL still handle indexes in this way? (where I mention this again).: Why does mysql drop index very very slow in a large table? (from the MySQL General Discussion Forum).MyISAM Index creation can be very lethargic. You can retrieve the most recent automatically generated AUTOINCREMENT value with the LASTINSERTID() SQL function or the mysqlinsertid() C API function. You must be doing something odd with your DDL or you have a very, very old version of MySQL. Updating an existing AUTOINCREMENT column value in an InnoDB table does not reset the AUTOINCREMENT sequence as it does for MyISAM and NDB tables.
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