the actual values in the index. For example, if you select all values greater than 10 for update, a gap lock prevents another transaction from inserting a new value that is greater than 10. The  supremum record  and  infimum record  represent the gaps containing all values greater than or less than all the current index values. See Also concurrency, gap lock, index, infimum record, isolation level, supremum record. gap lock general log general query log general tablespace generated column generated stored column generated virtual column Glassfish 6154 See Also J2EE. See virtual generated column. See stored generated column.  A column whose values are computed from an expression included in the column definition. A generated column can be  virtual  or  stored . See Also base column, stored generated column, virtual generated column. For more information, see Section 15.6.3.3, “General Tablespaces” . See Also file-per-table, system tablespace, table, tablespace. Contrast with  system tablespace  and  file-per-table  tablespace. Tables are added to a general tablespace using  CREATE TABLE  tbl_name  ... TABLESPACE [=] tablespace_name  or  ALTER TABLE  tbl_name  TABLESPACE [=]  tablespace_name  syntax.  A shared  InnoDB tablespace  created using  CREATE TABLESPACE  syntax. General tablespaces can be created outside of the MySQL data directory, are capable of holding multiple  tables , and support tables of all row formats. General tablespaces were introduced in MySQL 5.7.6. Records a broader range of queries than the  slow query log . Unlike the  binary log , which is used for replication, the general query log contains  SELECT  statements and does not maintain strict ordering. For more information, see Section 5.4.3, “The General Query Log” . See Also binary log, log, slow query log.  A type of  log  used for diagnosis and troubleshooting of SQL statements processed by the MySQL server. Can be stored in a file or in a database table. You must enable this feature through the  general_log  configuration option to use it. You can disable it for a specific connection through the  sql_log_off  configuration option. Gap locks are part of the tradeoff between performance and  concurrency , and are used in some transaction isolation levels  and not others. See Also gap, infimum record, lock, next-key lock, record lock, supremum record. See general query log.  A  lock  on a  gap  between index records, or a lock on the gap before the first or after the last index record. For example,  SELECT c1 FROM t WHERE c1 BETWEEN 10 and 20 FOR UPDATE;  prevents other transactions from inserting a value of 15 into the column  t.c1 , whether or not there was already any such value in the column, because the gaps between all existing values in the range are locked. Contrast with  record lock  and  next-key lock .