G List of things we want to add to MySQL in the future (The TODO)

Everything in this list is in the order it will be done. If you want to affect the priority order, please register a license or support us and tell us what you want to have done more quickly. See section 3 MySQL licensing and support.

G.1 Things that must done in the real near future

• Fail safe replication.
• Optimize, test and document transactions safe tables
• Subqueries. select id from t where grp in (select grp from g where u > 100)
• Allow mysqld to support many character sets at the same time.
• Add a temporary key buffer cache during insert/delete/update so that we can gracefully recover if the index file gets full.
• If you perform an ALTER TABLE on a table that is symlinked to another disk, create temporary tables on this disk.
• RENAME table as table, table as table [,...]
• Allow users to change startup options.
• FreeBSD and MIT-pthreads; Do sleeping threads take CPU?
• Check if locked threads take any CPU.
• Change to use mkstemp() instead of tempnam() for system that supports the call. We need to add a my_mkstemp() function in mysys and also change the cache code to not create the filename until we do the actual open.
• Allow join on key parts (optimization issue).
• Entry for DECRYPT().
• Remember FOREIGN key definitions in the `.frm' file.
• Server side cursors.
• Check if lockd works with modern Linux kernels; If not, we have to fix lockd! To test this, start mysqld with --enable-locking and run the different fork* test suits. They shouldn't give any errors if lockd works.
• Allow SQL variables in LIMIT, like in LIMIT @a,@b.
• Don't add automatic DEFAULT values to columns. Give an error when using an INSERT that doesn't contain a column that doesn't have a DEFAULT.
• Caching of queries and results. This should be done as a separated module that examines each query and if this is query is in the cache the cached result should be returned. When one updates a table one should remove as few queries as possible from the cache. This should give a big speed bost on machines with much RAM where queries are often repeated (like WWW applications). One idea would be to only cache queries of type: SELECT CACHED ....
• Fix `libmysql.c' to allow two mysql_query() commands in a row without reading results or give a nice error message when one does this.
• Optimize BIT type to take 1 bit (now BIT takes 1 char).
• Check why MIT-pthreads ctime() doesn't work on some FreeBSD systems.
• Add ORDER BY to update. This would be handy with functions like: generate_id(start,step).
• Add an IMAGE option to LOAD DATA INFILE to not update TIMESTAMP and AUTO_INCREMENT fields.
• Make LOAD DATA INFILE understand a syntax like:

  LOAD DATA INFILE 'file_name.txt' INTO TABLE tbl_name
  TEXT_FIELDS (text_field1, text_field2, text_field3)
  SET table_field1=concatenate(text_field1, text_field2), table_field3=23
  IGNORE text_field3
  

• LOAD DATA INFILE 'file_name' INTO TABLE 'table_name' ERRORS TO err_table_name which would cause any errors/warnings to be logged into the err_table_name table. That table would have a structure like:

  line_number    - line number in data file
  error_message  - the error/warning message
  and maybe
  data_line      - the line from the data file
  

• We should extend LOAD DATA INFILE so that we can skip over extra columns in the text file.
• Add true VARCHAR support (There is already support for this in MyISAM).
• Automatic output from mysql to netscape.
• LOCK DATABASES. (with various options)
• Change sort to allocate memory in ``hunks'' to get better memory utilization.
• DECIMAL and NUMERIC types can't read exponential numbers; Field_decimal::store(const char *from,uint len) must be recoded to fix this.
• Fix mysql.cc to do fewer malloc() calls when hashing field names.
• Functions: ADD_TO_SET(value,set) and REMOVE_FROM_SET(value,set)
• Add use of t1 JOIN t2 ON ... and t1 JOIN t2 USING ... Currently, you can only use this syntax with LEFT JOIN.
• Add full support for unsigned long long type.
• Function CASE.
• Many more variables for show status. Counts for: INSERT/DELETE/UPDATE statements. Records reads and updated. Selects on 1 table and selects with joins. Mean number of tables in select. Key buffer read/write hits (logical and real). ORDER BY, GROUP BY, temporary tables created.
• If you abort mysql in the middle of a query, you should open another connection and kill the old running query. Alternatively, an attempt should be made to detect this in the server.
• Add a handler interface for table information so you can use it as a system table. This would be a bit slow if you requested information about all tables, but very flexible. SHOW INFO FROM tbl_name for basic table information should be implemented.
• Add support for UNICODE.
• NATURAL JOIN.
• Oracle like CONNECT BY PRIOR ... to search hierarchy structures.
• RENAME DATABASE
• mysqladmin copy database new-database.
• Processlist should show number of queries/thread.
• DELETE and REPLACE options to the UPDATE statement (this will delete rows when one gets a dupplicate key error while updating).
• Change the format of DATETIME to store fractions of seconds.
• Add all missing ANSI92 and ODBC 3.0 types.
• Change table names from empty strings to NULL for calculated columns.
• Don't use 'Item_copy_string' on numerical values to avoid number->string->number conversion in case of: SELECT COUNT(*)*(id+0) FROM table_name GROUP BY id
• Make it possible to use the new GNU regexp library instead of the current one (The GNU library should be much faster than the old one).
• Change that ALTER TABLE doesn't abort clients that executes INSERT DELAYED.
• Allow select a from crash_me left join crash_me2 using (a); In this case a is assumed to come from the crash_me table.
• Fix that when columns referenced in an UPDATE clause contains the old values before the update started.
• Allow update of varibles in UPDATE statements. For example: UPDATE TABLE foo SET @a=a+b,a=@a, b=@a+c
• myisamchk, REPAIR and OPTIMIZE TABLE should be able to handle cases where the data and/or index files are symbolic links.
• Add simulation of pread()/pwrite() on windows to enable concurrent inserts.

G.2 Things that have to be done sometime

• Implement function: get_changed_tables(timeout,table1,table2,...)
• Atomic updates; This includes a language that one can even use for a set of stored procedures.
• update items,month set items.price=month.price where items.id=month.id;
• Change reading through tables to use memmap when possible. Now only compressed tables use memmap.
• Add a new privilege 'Show_priv' for SHOW commands.
• Make the automatic timestamp code nicer. Add timestamps to the update log with SET TIMESTAMP=#;
• Use read/write mutex in some places to get more speed.
• Full foreign key support. One probably wants to implement a procedural language first.
• Simple views (first on one table, later on any expression).
• Automatically close some tables if a table, temporary table or temporary files gets error 23 (not enough open files).
• When one finds a field=#, change all occurrences of field to #. Now this is only done for some simple cases.
• Change all const expressions with calculated expressions if possible.
• Optimize key = expression. At the moment only key = field or key = constant are optimized.
• Join some of the copy functions for nicer code.
• Change `sql_yacc.yy' to an inline parser to reduce its size and get better error messages (5 days).
• Change the parser to use only one rule per different number of arguments in function.
• Use of full calculation names in the order part. (For ACCESS97)
• UNION, MINUS, INTERSECT and FULL OUTER JOIN. (Currently only LEFT OUTER JOIN is supported)
• Allow UNIQUE on fields that can be NULL.
• SQL_OPTION MAX_SELECT_TIME=# to put a time limit on a query.
• Make the update log to a database.
• Negative LIMIT to retrieve data from the end.
• Alarm around client connect/read/write functions.
• Make a mysqld version which isn't multithreaded (3-5 days).
• Please note the changes to safe_mysqld: according to FSSTND (which Debian tries to follow) PID files should go into `/var/run/<progname>.pid' and log files into `/var/log'. It would be nice if you could put the "DATADIR" in the first declaration of "pidfile" and "log", so the placement of these files can be changed with a single statement.
• Better dynamic record layout to avoid fragmentation.
• UPDATE SET blob=read_blob_from_file('my_gif') where id=1;
• Allow a client to request logging.
• Add use of zlib() for gzip-ed files to LOAD DATA INFILE.
• Fix sorting and grouping of BLOB columns (partly solved now).
• Stored procedures. This is currently not regarded to be very important as stored procedures are not very standardized yet. Another problem is that true stored procedures make it much harder for the optimizer and in many cases the result is slower than before We will, on the other hand, add a simple (atomic) update language that can be used to write loops and such in the MySQL server.
• Change to use semaphores when counting threads. One should first implement a semaphore library to MIT-pthreads.
• Don't assign a new AUTO_INCREMENT value when one sets a column to 0. Use NULL instead.
• Add full support for JOIN with parentheses.
• Reuse threads for systems with a lot of connections.
• As an alternative for one thread / connection manage a pool of threads to handle the queries.
• Allow one to get more than one lock with GET_LOCK. When doing this, one must also handle the possible deadlocks this change will introduce.

Time is given according to amount of work, not real time.

G.3 Some things we don't have any plans to do

• Nothing; In the long run we plan to be fully ANSI 92 / ANSI 99 compliant.

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