Added db_metadata options to create database command

Summary:
Added new option db_metadata to the create database
`CREATE DATABASE [IF NOT EXISTS] db_name DB_METADATA [=] metadata`

The new option is stored in the db.opt file along with other database options like charset and read_only.
The options accepts any string value. If not specified, it writes empty string as the default value in the db.opt file.
To retrieve the option value for a particular database, the show command can be used as follows:
`SHOW CREATE DATABASE db_name`

Example Usage:

create database test2 charset utf8 read_only = true db_metadata '{\'shard_name\':\'myshard_for_test2\'}';
show create database test2;

Output:

+----------+--------------------------------------------------------------------------------------------------------------------------+
| Database | Create Database                                                                                                          |
+----------+--------------------------------------------------------------------------------------------------------------------------+
| test2    | CREATE DATABASE `test2` /*!40100 DEFAULT CHARACTER SET utf8 READ_ONLY DB_METADATA {'shard_name':'myshard_for_test2'} */ |
+----------+--------------------------------------------------------------------------------------------------------------------------+

Reviewed By: tianx

Differential Revision: D5358178

fbshipit-source-id: 4308ca2

mysql-test/r/db_metadata.result

@@ -0,0 +1,186 @@
+drop database if exists test2;
+drop database if exists test3;
+drop database if exists test4;
+drop database if exists test5;
+drop database if exists test6;
+drop database if exists test7;
+drop database if exists test8;
+drop database if exists test9;
+create database test2;
+show create database test2;
+Database	Create Database
+test2	CREATE DATABASE `test2` /*!40100 DEFAULT CHARACTER SET latin1 */
+default-character-set=latin1
+default-collation=latin1_swedish_ci
+db-read-only=0
+db-metadata=
+create database test3 character set utf8;
+show create database test3;
+Database	Create Database
+test3	CREATE DATABASE `test3` /*!40100 DEFAULT CHARACTER SET utf8 */
+default-character-set=utf8
+default-collation=utf8_general_ci
+db-read-only=0
+db-metadata=
+create database test4 read_only = true;
+show create database test4;
+Database	Create Database
+test4	CREATE DATABASE `test4` /*!40100 DEFAULT CHARACTER SET latin1 READ_ONLY */
+default-character-set=latin1
+default-collation=latin1_swedish_ci
+db-read-only=1
+db-metadata=
+create database test5 db_metadata = "{\"shard\":\"test5_shard\"}";
+show create database test5;
+Database	Create Database
+test5	CREATE DATABASE `test5` /*!40100 DEFAULT CHARACTER SET latin1 DB_METADATA {"shard":"test5_shard"} */
+default-character-set=latin1
+default-collation=latin1_swedish_ci
+db-read-only=0
+db-metadata={"shard":"test5_shard"}
+create database test6 character set utf8 db_metadata = "{\"shard\":\"test6_shard\"}";
+show create database test6;
+Database	Create Database
+test6	CREATE DATABASE `test6` /*!40100 DEFAULT CHARACTER SET utf8 DB_METADATA {"shard":"test6_shard"} */
+default-character-set=utf8
+default-collation=utf8_general_ci
+db-read-only=0
+db-metadata={"shard":"test6_shard"}
+create database test7 read_only = true db_metadata = "{\"shard\":\"test7_shard\"}";
+show create database test7;
+Database	Create Database
+test7	CREATE DATABASE `test7` /*!40100 DEFAULT CHARACTER SET latin1 READ_ONLY DB_METADATA {"shard":"test7_shard"} */
+default-character-set=latin1
+default-collation=latin1_swedish_ci
+db-read-only=1
+db-metadata={"shard":"test7_shard"}
+create database test8 character set utf8 read_only = true;
+show create database test8;
+Database	Create Database
+test8	CREATE DATABASE `test8` /*!40100 DEFAULT CHARACTER SET utf8 READ_ONLY */
+default-character-set=utf8
+default-collation=utf8_general_ci
+db-read-only=1
+db-metadata=
+create database test9 character set utf8 read_only = true db_metadata = "{\"shard\":\"test9_shard\"}";
+show create database test9;
+Database	Create Database
+test9	CREATE DATABASE `test9` /*!40100 DEFAULT CHARACTER SET utf8 READ_ONLY DB_METADATA {"shard":"test9_shard"} */
+default-character-set=utf8
+default-collation=utf8_general_ci
+db-read-only=1
+db-metadata={"shard":"test9_shard"}
+alter database test3 character set ascii;
+show create database test3;
+Database	Create Database
+test3	CREATE DATABASE `test3` /*!40100 DEFAULT CHARACTER SET ascii */
+default-character-set=ascii
+default-collation=ascii_general_ci
+db-read-only=0
+db-metadata=
+alter database test4 read_only = true;
+show create database test4;
+Database	Create Database
+test4	CREATE DATABASE `test4` /*!40100 DEFAULT CHARACTER SET latin1 READ_ONLY */
+default-character-set=latin1
+default-collation=latin1_swedish_ci
+db-read-only=1
+db-metadata=
+alter database test5 db_metadata = "{\"shard\":\"test5_shard_altered\"}";
+show create database test5;
+Database	Create Database
+test5	CREATE DATABASE `test5` /*!40100 DEFAULT CHARACTER SET latin1 DB_METADATA {"shard":"test5_shard_altered"} */
+default-character-set=latin1
+default-collation=latin1_swedish_ci
+db-read-only=0
+db-metadata={"shard":"test5_shard_altered"}
+alter database test5 character set ascii;
+show create database test5;
+Database	Create Database
+test5	CREATE DATABASE `test5` /*!40100 DEFAULT CHARACTER SET ascii DB_METADATA {"shard":"test5_shard_altered"} */
+default-character-set=ascii
+default-collation=ascii_general_ci
+db-read-only=0
+db-metadata={"shard":"test5_shard_altered"}
+alter database test5 read_only = true;
+show create database test5;
+Database	Create Database
+test5	CREATE DATABASE `test5` /*!40100 DEFAULT CHARACTER SET ascii READ_ONLY DB_METADATA {"shard":"test5_shard_altered"} */
+default-character-set=ascii
+default-collation=ascii_general_ci
+db-read-only=1
+db-metadata={"shard":"test5_shard_altered"}
+alter database test5 character set utf8 read_only = false;
+show create database test5;
+Database	Create Database
+test5	CREATE DATABASE `test5` /*!40100 DEFAULT CHARACTER SET utf8 DB_METADATA {"shard":"test5_shard_altered"} */
+default-character-set=utf8
+default-collation=utf8_general_ci
+db-read-only=0
+db-metadata={"shard":"test5_shard_altered"}
+alter database test5 db_metadata "";
+show create database test5;
+Database	Create Database
+test5	CREATE DATABASE `test5` /*!40100 DEFAULT CHARACTER SET utf8 */
+default-character-set=utf8
+default-collation=utf8_general_ci
+db-read-only=0
+db-metadata=
+alter database test5 db_metadata "{\"shard\":\"Really long shard name. Really long shard name. Really long shard name. Really long shard name. Really long shard name. Really long shard name. Really long shard name. Really long shard name. Really long shard name. Really long shard name. Really long shard name. Really long shard name. Really long shard name. Really long shard name. Really long shard name. Really long shard name. Really long shard name. Really long shard name. Really long shard name. Really long shard name. Really long shard name. Really long shard name. Really long shard name. Really long shard name. Really long shard name. Really long shard name. Really long shard name. Really long shard name. Really long shard name. Really long shard name. Really long shard name. Really long shard name. Really long shard name. Really long shard name. Really long shard name. Really long shard name. Really long shard name. Really long shard name. Really long shard name. Really long shard name. Really long shard name. Really long shard name. Fin\"}";
+show create database test5;
+Database	Create Database
+test5	CREATE DATABASE `test5` /*!40100 DEFAULT CHARACTER SET utf8 DB_METADATA {"shard":"Really long shard name. Really long shard name. Really long shard name. Really long shard name. Really long shard name. Really long shard name. Really long shard name. Really long shard name. Really long shard name. Really long shard name. Really long shard name. Really long shard name. Really long shard name. Really long shard name. Really long shard name. Really long shard name. Really long shard name. Really long shard name. Really long shard name. Really long shard name. Really long shard name. Really long shard name. Really long shard name. Really long shard name. Really long shard name. Really long shard name. Really long shard name. Really long shard name. Really long shard name. Really long shard name. Really long shard name. Really long shard name. Really long shard name. Really long shard name. Really long shard name. Really long shard name. Really long shard name. Really long shard name. Really long shard name. Really long shard name. Really long shard name. Really long shard name. Fin"} */
+default-character-set=utf8
+default-collation=utf8_general_ci
+db-read-only=0
+db-metadata={"shard":"Really long shard name. Really long shard name. Really long shard name. Really long shard name. Really long shard name. Really long shard name. Really long shard name. Really long shard name. Really long shard name. Really long shard name. Really long shard name. Really long shard name. Really long shard name. Really long shard name. Really long shard name. Really long shard name. Really long shard name. Really long shard name. Really long shard name. Really long shard name. Really long shard name. Really long shard name. Really long shard name. Really long shard name. Really long shard name. Really long shard name. Really long shard name. Really long shard name. Really long shard name. Really long shard name. Really long shard name. Really long shard name. Really long shard name. Really long shard name. Really long shard name. Really long shard name. Really long shard name. Really long shard name. Really long shard name. Really long shard name. Really long shard name. Really long shard name. Fin"}
+alter database test5 db_metadata "{\"shard\":\"Really long shard name. Really long shard name. Really long shard name. Really long shard name. Really long shard name. Really long shard name. Really long shard name. Really long shard name. Really long shard name. Really long shard name. Really long shard name. Really long shard name. Really long shard name. Really long shard name. Really long shard name. Really long shard name. Really long shard name. Really long shard name. Really long shard name. Really long shard name. Really long shard name. Really long shard name. Really long shard name. Really long shard name. Really long shard name. Really long shard name. Really long shard name. Really long shard name. Really long shard name. Really long shard name. Really long shard name. Really long shard name. Really long shard name. Really long shard name. Really long shard name. Really long shard name. Really long shard name. Really long shard name. Really long shard name. Really long shard name. Really long shard name. Really long shard name. Really long shard name. Fin\"}";;
+ERROR HY000: Metadata for the database is too long. Max length is 1024 bytes
+alter database test6 character set ascii db_metadata = "{\"shard\":\"test6_shard_altered\"}";
+show create database test6;
+Database	Create Database
+test6	CREATE DATABASE `test6` /*!40100 DEFAULT CHARACTER SET ascii DB_METADATA {"shard":"test6_shard_altered"} */
+default-character-set=ascii
+default-collation=ascii_general_ci
+db-read-only=0
+db-metadata={"shard":"test6_shard_altered"}
+alter database test7 read_only = true db_metadata = "{\"shard\":\"test7_shard_altered\"}";
+show create database test7;
+Database	Create Database
+test7	CREATE DATABASE `test7` /*!40100 DEFAULT CHARACTER SET latin1 READ_ONLY DB_METADATA {"shard":"test7_shard_altered"} */
+default-character-set=latin1
+default-collation=latin1_swedish_ci
+db-read-only=1
+db-metadata={"shard":"test7_shard_altered"}
+alter database test8 character set ascii read_only = true;
+show create database test8;
+Database	Create Database
+test8	CREATE DATABASE `test8` /*!40100 DEFAULT CHARACTER SET ascii READ_ONLY */
+default-character-set=ascii
+default-collation=ascii_general_ci
+db-read-only=1
+db-metadata=
+alter database test9 character set ascii read_only = true db_metadata = "{\"shard\":\"test9_shard_altered\"}";
+show create database test9;
+Database	Create Database
+test9	CREATE DATABASE `test9` /*!40100 DEFAULT CHARACTER SET ascii READ_ONLY DB_METADATA {"shard":"test9_shard_altered"} */
+default-character-set=ascii
+default-collation=ascii_general_ci
+db-read-only=1
+db-metadata={"shard":"test9_shard_altered"}
+show create database information_schema;
+Database	Create Database
+information_schema	CREATE DATABASE `information_schema` /*!40100 DEFAULT CHARACTER SET utf8 */
+show create database mysql;
+Database	Create Database
+mysql	CREATE DATABASE `mysql` /*!40100 DEFAULT CHARACTER SET latin1 */
+alter database information_schema db_metadata "{\"shard\":\"is_shard\"}";;
+ERROR 42000: Access denied for user 'root'@'localhost' to database 'information_schema'
+drop database if exists test2;
+drop database if exists test3;
+drop database if exists test4;
+drop database if exists test5;
+drop database if exists test6;
+drop database if exists test7;
+drop database if exists test8;
+drop database if exists test9;

mysql-test/t/db_metadata.test

@@ -0,0 +1,147 @@
+# Test per-database database-metadata attribute
+--source include/have_innodb.inc
+connection default;
+
+--disable_warnings
+drop database if exists test2;
+drop database if exists test3;
+drop database if exists test4;
+drop database if exists test5;
+drop database if exists test6;
+drop database if exists test7;
+drop database if exists test8;
+drop database if exists test9;
+--enable_warnings
+
+--disable_query_log
+let $MYSQLD_DATADIR= `select @@datadir`;
+--enable_query_log
+
+--error 1
+file_exists $MYSQLD_DATADIR/mysql/db.opt;
+--error 1
+file_exists $MYSQLD_DATADIR/test/db.opt;
+
+# create database without any options
+create database test2;
+show create database test2;
+--exec cat $MYSQLD_DATADIR/test2/db.opt;
+
+# create database with character set
+create database test3 character set utf8;
+show create database test3;
+--exec cat $MYSQLD_DATADIR/test3/db.opt;
+
+# create database with read only
+create database test4 read_only = true;
+show create database test4;
+--exec cat $MYSQLD_DATADIR/test4/db.opt;
+
+# create database with db metadata
+create database test5 db_metadata = "{\"shard\":\"test5_shard\"}";
+show create database test5;
+--exec cat $MYSQLD_DATADIR/test5/db.opt;
+
+# create database with character set and db metadata
+create database test6 character set utf8 db_metadata = "{\"shard\":\"test6_shard\"}";
+show create database test6;
+--exec cat $MYSQLD_DATADIR/test6/db.opt;
+
+# create database with read only and db metadata
+create database test7 read_only = true db_metadata = "{\"shard\":\"test7_shard\"}";
+show create database test7;
+--exec cat $MYSQLD_DATADIR/test7/db.opt;
+
+# create database with character set and read only
+create database test8 character set utf8 read_only = true;
+show create database test8;
+--exec cat $MYSQLD_DATADIR/test8/db.opt;
+
+# create database with character set, read only and db metadata
+create database test9 character set utf8 read_only = true db_metadata = "{\"shard\":\"test9_shard\"}";
+show create database test9;
+--exec cat $MYSQLD_DATADIR/test9/db.opt;
+
+# alter database tests
+
+# alter database character set
+alter database test3 character set ascii;
+show create database test3;
+--exec cat $MYSQLD_DATADIR/test3/db.opt;
+
+# alter database read only
+alter database test4 read_only = true;
+show create database test4;
+--exec cat $MYSQLD_DATADIR/test4/db.opt;
+
+# alter database db metadata
+alter database test5 db_metadata = "{\"shard\":\"test5_shard_altered\"}";
+show create database test5;
+--exec cat $MYSQLD_DATADIR/test5/db.opt;
+
+# alter database character set but keep db metadata intact
+alter database test5 character set ascii;
+show create database test5;
+--exec cat $MYSQLD_DATADIR/test5/db.opt;
+
+# alter database read only but keep db metadata intact
+alter database test5 read_only = true;
+show create database test5;
+--exec cat $MYSQLD_DATADIR/test5/db.opt;
+
+# alter database character set and read only but keep db metadata intact
+alter database test5 character set utf8 read_only = false;
+show create database test5;
+--exec cat $MYSQLD_DATADIR/test5/db.opt;
+
+# alter database reset db metadata
+alter database test5 db_metadata "";
+show create database test5;
+--exec cat $MYSQLD_DATADIR/test5/db.opt;
+
+# alter database set db metadata to max length string
+alter database test5 db_metadata "{\"shard\":\"Really long shard name. Really long shard name. Really long shard name. Really long shard name. Really long shard name. Really long shard name. Really long shard name. Really long shard name. Really long shard name. Really long shard name. Really long shard name. Really long shard name. Really long shard name. Really long shard name. Really long shard name. Really long shard name. Really long shard name. Really long shard name. Really long shard name. Really long shard name. Really long shard name. Really long shard name. Really long shard name. Really long shard name. Really long shard name. Really long shard name. Really long shard name. Really long shard name. Really long shard name. Really long shard name. Really long shard name. Really long shard name. Really long shard name. Really long shard name. Really long shard name. Really long shard name. Really long shard name. Really long shard name. Really long shard name. Really long shard name. Really long shard name. Really long shard name. Fin\"}";
+show create database test5;
+--exec cat $MYSQLD_DATADIR/test5/db.opt;
+
+# alter database exceed db metadata max length
+--error ER_DB_METADATA_TOO_LONG
+--eval alter database test5 db_metadata \"{\\\"shard\\\":\\\"Really long shard name. Really long shard name. Really long shard name. Really long shard name. Really long shard name. Really long shard name. Really long shard name. Really long shard name. Really long shard name. Really long shard name. Really long shard name. Really long shard name. Really long shard name. Really long shard name. Really long shard name. Really long shard name. Really long shard name. Really long shard name. Really long shard name. Really long shard name. Really long shard name. Really long shard name. Really long shard name. Really long shard name. Really long shard name. Really long shard name. Really long shard name. Really long shard name. Really long shard name. Really long shard name. Really long shard name. Really long shard name. Really long shard name. Really long shard name. Really long shard name. Really long shard name. Really long shard name. Really long shard name. Really long shard name. Really long shard name. Really long shard name. Really long shard name. Really long shard name. Fin\\\"}\";
+
+# alter database character set and db metadata
+alter database test6 character set ascii db_metadata = "{\"shard\":\"test6_shard_altered\"}";
+show create database test6;
+--exec cat $MYSQLD_DATADIR/test6/db.opt;
+
+# alter database read only and db metadata
+alter database test7 read_only = true db_metadata = "{\"shard\":\"test7_shard_altered\"}";
+show create database test7;
+--exec cat $MYSQLD_DATADIR/test7/db.opt;
+
+# alter database character set and read only
+alter database test8 character set ascii read_only = true;
+show create database test8;
+--exec cat $MYSQLD_DATADIR/test8/db.opt;
+
+# alter database character set, read only and db metadata
+alter database test9 character set ascii read_only = true db_metadata = "{\"shard\":\"test9_shard_altered\"}";
+show create database test9;
+--exec cat $MYSQLD_DATADIR/test9/db.opt;
+
+# ensure information_schema and mysql tables are intact
+show create database information_schema;
+show create database mysql;
+--error ER_DBACCESS_DENIED_ERROR
+--eval alter database information_schema db_metadata \"{\\"shard\\":\\"is_shard\\"}\";
+
+# cleanup
+--disable_warnings
+drop database if exists test2;
+drop database if exists test3;
+drop database if exists test4;
+drop database if exists test5;
+drop database if exists test6;
+drop database if exists test7;
+drop database if exists test8;
+drop database if exists test9;
+--enable_warnings

sql/handler.h

@@ -39,6 +39,7 @@
 #include <regex>
 #include <vector>
 #include <unordered_set>
+#include <sql_string.h>
 
 class Alter_info;
 
@@ -1094,6 +1095,7 @@ typedef struct st_ha_create_information
                                        means it is explicitly set to default or
                                        it is not specified in alter */
   enum enum_db_read_only db_read_only;
+  String db_metadata;
   LEX_STRING connect_string;
   const char *password, *tablespace;
   LEX_STRING comment;

sql/lex.h

@@ -168,6 +168,7 @@ static SYMBOL symbols[] = {
   { "DAY_MICROSECOND",	SYM(DAY_MICROSECOND_SYM)},
   { "DAY_MINUTE",	SYM(DAY_MINUTE_SYM)},
   { "DAY_SECOND",	SYM(DAY_SECOND_SYM)},
+  { "DB_METADATA", SYM(DB_METADATA_SYM)},
   { "DEALLOCATE",       SYM(DEALLOCATE_SYM)},
   { "DEC",		SYM(DECIMAL_SYM)},
   { "DECIMAL",		SYM(DECIMAL_SYM)},

sql/share/errmsg-utf8.txt

@@ -7323,6 +7323,12 @@ ER_CANT_SET_DEPENDENCY_REPLICATION_WITHOUT_IDEMPOTENT_RECOVERY
 ER_SLAVE_WORKER_STOPPED_PREVIOUS_THD_ERROR
   eng "Slave worker has stopped after at least one previous worker encountered an error when mts_dependency_order_commits was enabled. To preserve commit order, the last transaction executed by this thread has not been committed. When restarting the slave after fixing any failed threads, you should fix this worker as well."
 
+ER_DB_METADATA_TOO_LONG
+  eng "Metadata for the database is too long. Max length is %d bytes"
+
+ER_DB_METADATA_READ_ERROR
+  eng "Error reading db metadata option: '%-.64s'"
+
 #
 #  End of 5.6 error messages.
 #