DISTINCT optimization

Fixes when using column privileges
Manual updates


Docs/manual.texi:
  Comments from MySQL training + distinct optimization
extra/my_print_defaults.c:
  Added --defaults-extra-file
include/my_sys.h:
  Added --defaults-extra-file
mysys/default.c:
  Added --defaults-extra-file
sql/sql_acl.cc:
  Tables with only column privileges didn't show up in SHOW GRANTS or SHOW TABLES
sql/sql_select.cc:
  DISTINCT optimization
sql/sql_select.h:
  DISTINCT optimization
BitKeeper/etc/logging_ok:
  Logging to logging@openlogging.org accepted

BitKeeper/etc/logging_ok

@@ -1,25 +1 @@
-bk@work.mysql.com
+monty@tramp.mysql.fi
-davida@work.mysql.com
-jamppa@work.mysql.com
-jcole@ham.spaceapes.com
-jcole@jcole.burghcom.com
-jcole@nslinux.bedford.progress.com
-jcole@tetra.bedford.progress.com
-jcole@tetra.spaceapes.com
-matt@work.mysql.com
-monty@donna.mysql.com
-monty@work.mysql.com
-mwagner@evoq.home.mwagner.org
-nusphere@main.burghcom.com
-paul@central.snake.net
-paul@work.mysql.com
-sasha@mysql.sashanet.com
-sasha@work.mysql.com
-serg@infomag.ape.relarn.ru
-serg@work.mysql.com
-sinisa@work.mysql.com
-spurr@nslinux.bedford.progress.com
-tim@localhost.polyesthetic.msg
-tim@threads.polyesthetic.msg
-tim@work.mysql.com
-tonu@work.mysql.com

Docs/manual.texi

@@ -305,14 +305,14 @@ Post-installation Setup and Testing
 * Command-line options::        Command-line options
 * Option files::                Option files
 
-Is there anything special to do when upgrading/downgrading MySQL?
+Is There Anything Special to Do when Upgrading/Downgrading MySQL?
 
 * Upgrading-from-3.22::         Upgrading from a 3.22 version to 3.23
 * Upgrading-from-3.21::         Upgrading from a 3.21 version to 3.22
 * Upgrading-from-3.20::         Upgrading from a 3.20 version to 3.21
 * Upgrading-to-arch::           Upgrading to another architecture
 
-How standards-compatible is MySQL?
+How Standards-compatible Is MySQL?
 
 * Extensions to ANSI::          @strong{MySQL} extensions to ANSI SQL92
 * Ansi mode::                   Running @strong{MySQL} in ANSI mode
@@ -321,7 +321,7 @@ How standards-compatible is MySQL?
 * Standards::                   What standards does @strong{MySQL} follow?
 * Commit-rollback::             How to cope without @code{COMMIT}-@code{ROLLBACK}
 
-Functionality missing from MySQL
+Functionality Missing from MySQL
 
 * Missing Sub-selects::         Sub-selects
 * Missing SELECT INTO TABLE::   @code{SELECT INTO TABLE}
@@ -335,7 +335,7 @@ Foreign Keys
 
 * Broken Foreign KEY::          Reasons NOT to use foreign keys
 
-The MySQL access privilege system
+The MySQL Access Privilege System
 
 * General security::            General security
 * Security::                    How to make @strong{MySQL} secure against crackers
@@ -353,7 +353,7 @@ The MySQL access privilege system
 * Passwords::                   How to set up passwords
 * Access denied::               Causes of @code{Access denied} errors
 
-MySQL language reference
+MySQL Language Reference
 
 * Literals::                    Literals: how to write strings and numbers
 * Variables::                   User variables
@@ -394,7 +394,7 @@ MySQL language reference
 * CREATE FUNCTION::             @code{CREATE FUNCTION} syntax
 * Reserved words::              Is @strong{MySQL} picky about reserved words?
 
-Literals: how to write strings and numbers
+Literals: How to Write Strings and Numbers
 
 * String syntax::               Strings
 * Number syntax::               Numbers
@@ -402,11 +402,11 @@ Literals: how to write strings and numbers
 * NULL values::                 @code{NULL} values
 * Legal names::                 Database, table, index, column and alias names
 
-Database, table, index, column and alias names
+Database, Table, Index, Column, and Alias Names
 
 * Name case sensitivity::       Case sensitivity in names
 
-Column types
+Column Types
 
 * Storage requirements::        Column type storage requirements
 * Numeric types::               Numeric types
@@ -417,21 +417,21 @@ Column types
 * Multiple-column indexes::     Multiple-column indexes
 * Other-vendor column types::   Using column types from other database engines
 
-Date and time types
+Date and Time Types
 
 * Y2K issues::                  Y2K issues and date types
 * DATETIME::                    The @code{DATETIME}, @code{DATE} and @code{TIMESTAMP} types
 * TIME::                        The @code{TIME} type
 * YEAR::                        The @code{YEAR} type
 
-String types
+String Types
 
 * CHAR::                        The @code{CHAR} and @code{VARCHAR} types
 * BLOB::                        The @code{BLOB} and @code{TEXT} types
 * ENUM::                        The @code{ENUM} type
 * SET::                         The @code{SET} type
 
-Functions for use in @code{SELECT} and @code{WHERE} clauses
+Functions for Use in @code{SELECT} and @code{WHERE} Clauses
 
 * Grouping functions::          Grouping functions
 * Arithmetic functions::        Normal arithmetic operations
@@ -447,7 +447,7 @@ Functions for use in @code{SELECT} and @code{WHERE} clauses
 * Miscellaneous functions::     Miscellaneous functions
 * Group by functions::          Functions for @code{GROUP BY} clause
 
-@code{CREATE TABLE} syntax
+@code{CREATE TABLE} Syntax
 
 * Silent column changes::       Silent column changes
 
@@ -580,6 +580,7 @@ Speed of queries that access or update data
 * Estimating performance::      Estimating query performance
 * SELECT speed::                Speed of @code{SELECT} queries
 * Where optimizations::         How MySQL optimizes @code{WHERE} clauses
+* DISTINCT optimization::       
 * LEFT JOIN optimization::      How MySQL optimizes @code{LEFT JOIN}
 * LIMIT optimization::          How MySQL optimizes @code{LIMIT}
 * Insert speed::                Speed of @code{INSERT} queries
@@ -4393,14 +4394,47 @@ last version number is newer than yours).  We have tried to fix only
 fatal bugs and make small, relatively safe changes to that version.
 @end itemize
 
-The second decision to make is whether you want to use a source distribution or
+The second decision to make is whether you want to use a source
-a binary distribution:
+distribution or a binary distribution.  In most cases you should probably
+use a binary distribution, if there exist one for your platform, as this
+is generally, it will be easier to install than a source distribution.
+
+In the following cases you will probably be better of with a source
+installation:
 
 @itemize @bullet
 @item
-If you want to run @strong{MySQL} on a platform for which a current binary
+If you want to install @strong{MySQL} at some explicit location. (The standard
-distribution exists, use that.  Generally, it will be easier to install
+binary distributions are 'ready to run' at any place, but you may want
-than a source distribution.
+to get even more flexibility).
+
+@item
+If you want to configure @code{mysqld} with some extra feature that is NOT in
+the standard binary distributions. Here follows a list of the most common
+extra options that you may want to use
+
+@itemize @bullet
+@item --with-berkeley-db
+@item --with-raid
+@item --with-libwrap
+@item --with-named-z-lib  (This is done for some of the binaries)
+@item --with-debugging[=full]
+@end itemize
+
+@item
+The default binary distribution is normally compiled with support
+for all characters sets and should work on a variety of processors from
+the same processor family.
+
+If you want a faster @strong{MySQL} server you may want to recompile it
+with support for only the character sets you need, use a better compiler
+(like pgcc) or use compiler options that are better optimized for your
+processor.
+
+@item
+If you have found a bug and reported it to the @strong{MySQL}
+development team you will probably got a patch that you need to apply to
+the source distribution to get the bug fixed.
 
 @item
 If you want to read (and/or modify) the C and C++ code that makes up
@@ -9122,6 +9156,7 @@ for clients from option files.
 @item @strong{Filename} @tab @strong{Purpose}
 @item @code{/etc/my.cnf} @tab Global options
 @item @code{DATADIR/my.cnf} @tab Server-specific options
+@item @code{defaults-extra-file} @tab The file specified with --defaults-extra-file=#
 @item @code{~/.my.cnf} @tab User-specific options
 @end multitable
 
@@ -9233,15 +9268,19 @@ there are sample configuration files for small, medium, large, and very
 large systems.  You can copy @file{my-xxxx.cnf} to your home directory
 (rename the copy to @file{.my.cnf}) to experiment with this.
 
-To tell a @strong{MySQL} program not to read any option files, specify
+All @strong{MySQL} clients that support option files support the
-@code{--no-defaults} as the first option on the command line.  This
+following options:
-@strong{MUST} be the first option or it will have no effect!
-If you want to check which options are used, you can give the option
-@code{--print-defaults} as the first option.
 
-If you want to force the use of a specific config file, you can use the option
+@multitable @columnfractions .40 .60
-@code{--defaults-file=full-path-to-default-file}. If you do this, only the
+@item --no-defaults @tab Don't read any option files.
-specified file will be read.
+@item --print-defaults @tab Print the program name and all options that it will get.
+@item --defaults-file=full-path-to-default-file @tab Only use the given configuration file.
+@item --defaults-extra-file=full-path-to-default-file @tab Read this configuration file after the global configuration file but before the user configuration file.
+@end multitable
+
+Note that the above options must be first on the command line to work!
+@code{--print-defaults} may however be used directly after the
+@code{--defaults-xxx-file} commands.
 
 Note for developers:  Option file handling is implemented simply by
 processing all matching options (that is, options in the appropriate group)
@@ -9252,6 +9291,19 @@ read option files, you need add only two lines to give it that capability.
 Check the source code of any of the standard @strong{MySQL} clients to see
 how to do this.
 
+In shell scripts you can use the @file{my_print_defaults} command to parse the
+config files:
+
+@example
+
+shell> my_print_defaults client mysql
+--port=3306
+--socket=/tmp/mysql.sock
+--no-auto-rehash
+@end example
+
+The above output contains all options for the groups 'client' and 'mysql'.
+
 @node Upgrade,  , Post-installation, Installing
 @section Is There Anything Special to Do when Upgrading/Downgrading MySQL?
 @cindex upgrading
@@ -20035,6 +20087,9 @@ resolve the query. Here follows an explanation of the different text
 strings that can be found in this column:
 
 @table @code
+@item Distinct
+@strong{MySQL} will not continue searching for more rows for the current row
+combination after it has found the first matching row.
 @item Not exists
 @strong{MySQL} was able to do a @code{LEFT JOIN} optimization on the
 query and will not examine more rows in this table for a row combination
@@ -20779,9 +20834,28 @@ The biggest differences between the ANSI SQL and @strong{MySQL} versions of
 @code{GRANT} are:
 
 @itemize @bullet
+@item
+In @strong{MySQL} privileges are given for an username + hostname combination
+and not only for an username.
+
 @item
 ANSI SQL doesn't have global or database-level privileges and ANSI SQL
 doesn't support all privilege types that @strong{MySQL} supports.
+@strong{MySQL} doesn't support the ANSI SQL @code{TRIGGER}, @code{EXECUTE} or
+@code{UNDER} privileges.
+
+@item
+ANSI SQL privileges are structured in a hierarchal manner. If you remove
+an user, all privileges the user has granted are revoked. In
+@strong{MySQL} the granted privileges are not automaticly revoked, but
+you have to revoke these yourself if needed.
+
+@item
+If you in @code{MySQL} have the @code{INSERT} grant on only part of the
+columns in a table, you can execute @code{INSERT} statements on the
+table; The columns for which you don't have the @code{INSERT} privilege
+will set to their default values. ANSI SQL requires you to have the
+@code{INSERT} privilege on all columns.
 
 @item
 When you drop a table in ANSI SQL, all privileges for the table are revoked.
@@ -26092,6 +26166,7 @@ great tool to find out if this is a problem with your query.
 * Estimating performance::      Estimating query performance
 * SELECT speed::                Speed of @code{SELECT} queries
 * Where optimizations::         How MySQL optimizes @code{WHERE} clauses
+* DISTINCT optimization::       
 * LEFT JOIN optimization::      How MySQL optimizes @code{LEFT JOIN}
 * LIMIT optimization::          How MySQL optimizes @code{LIMIT}
 * Insert speed::                Speed of @code{INSERT} queries
@@ -26171,7 +26246,7 @@ time for a large table!
 
 @cindex optimizations
 @findex WHERE
-@node Where optimizations, LEFT JOIN optimization, SELECT speed, Query Speed
+@node Where optimizations, DISTINCT optimization, SELECT speed, Query Speed
 @subsection How MySQL optimizes @code{WHERE} clauses
 
 The @code{WHERE} optimizations are put in the @code{SELECT} part here because
@@ -26244,18 +26319,14 @@ possibilities. If all columns in @code{ORDER BY} and in @code{GROUP
 BY} come from the same table, then this table is preferred first when
 joining.
 @item
-If there is an @code{ORDER BY} clause and a different @code{GROUP BY} clause,
+If there is an @code{ORDER BY} clause and a different @code{GROUP BY}
-or if the @code{ORDER BY} or @code{GROUP BY}
+clause, or if the @code{ORDER BY} or @code{GROUP BY} contains columns
-contains columns from tables other than the first table in the join
+from tables other than the first table in the join queue, a temporary
-queue, a temporary table is created.
+table is created.
 @item
 If you use @code{SQL_SMALL_RESULT}, @strong{MySQL} will use an in-memory
 temporary table.
 @item
-As @code{DISTINCT} is converted to a @code{GROUP BY} on all columns,
-@code{DISTINCT} combined with @code{ORDER BY} will in many cases also need
-a temporary table.
-@item
 Each table index is queried and the best index that spans fewer than 30% of
 the rows is used. If no such index can be found, a quick table scan is used.
 @item
@@ -26298,9 +26369,32 @@ mysql> SELECT ... FROM tbl_name ORDER BY key_part1,key_part2,...
 mysql> SELECT ... FROM tbl_name ORDER BY key_part1 DESC,key_part2 DESC,...
 @end example
 
+@findex DISTINCT
+@cindex optimizing, DISTINCT
+@node DISTINCT optimization, LEFT JOIN optimization, Where optimizations, Query Speed
+@subsection How MySQL optimizes @code{DISTINCT}
+
+@code{DISTINCT} is converted to a @code{GROUP BY} on all columns,
+@code{DISTINCT} combined with @code{ORDER BY} will in many cases also
+need a temporary table.
+
+When combining @code{LIMIT #} with @code{DISTINCT}, @strong{MySQL} will stop
+as soon as it finds @code{#} unique rows.
+
+If you don't use columns from all used tables, @strong{MySQL} will stop
+the scanning of the not used tables as soon as it has found the first match.
+
+@example
+SELECT DISTINCT t1.a FROM t1,t2 where t1.a=t2.a;
+@end example
+
+In the case, assuming t1 is used before t2 (check with @code{EXPLAIN}), then
+@strong{MySQL} will stop reading from t2 (for that particular row in t1)
+when the first row in t2 is found.
+
 @findex LEFT JOIN
 @cindex optimizing, LEFT JOIN
-@node LEFT JOIN optimization, LIMIT optimization, Where optimizations, Query Speed
+@node LEFT JOIN optimization, LIMIT optimization, DISTINCT optimization, Query Speed
 @subsection How MySQL optimizes @code{LEFT JOIN} and @code{RIGHT JOIN}
 
 @code{A LEFT JOIN B} is in @strong{MySQL} implemented as follows:
@@ -31397,6 +31491,10 @@ Load the privilege tables with: @code{mysqladmin -h hostname
 flush-privileges} or with the SQL command @code{FLUSH PRIVILEGES}.
 @end enumerate
 
+Note that after you started @code{mysqld} with @code{--skip-grant-tables},
+any usage of @code{GRANT} commands will give you an @code{Unknown command}
+error until you have executed @code{FLUSH PRIVILEGES}.
+
 @cindex files, permissions
 @cindex error mesaages, can't find file
 @cindex files, not found message
@@ -37760,6 +37858,16 @@ though, so 3.23 is not released as a stable version yet.
 @appendixsubsec Changes in release 3.23.26
 @itemize @bullet
 @item
+Added optimization of queries where @code{DISTINCT} is only used on columns
+from some of the tables.
+@item
+Allow floating point numbers where there are no sign after the exponent
+(like 1e1).
+@item
+@code{SHOW GRANTS} didn't always show all column grants.
+@item
+Added @code{--default-extra-file=#} to all @strong{MySQL} clients.
+@item
 Automatic repair of @code{MyISAM} tables.
 @item
 Columns referenced in @code{INSERT} are are now properly initialized.

extra/my_print_defaults.c

@@ -32,6 +32,8 @@ static struct option long_options[] =
 {
   {"config-file",	required_argument, 0,	'c'},
   {"defaults-file",	required_argument, 0,	'c'},
+  {"defaults-extra-file", required_argument, 0,	'e'},
+  {"extra-file", 	required_argument, 0,	'e'},
   {"no-defaults",	no_argument,	   0,	'd'},
   {"help",		no_argument,	   0,	'?'},
   {"version",		no_argument,	   0,	'V'},
@@ -40,7 +42,7 @@ static struct option long_options[] =
 
 static void usage(my_bool version)
 {
-  printf("%s  Ver 1.1 for %s at %s\n",my_progname,SYSTEM_TYPE,
+  printf("%s  Ver 1.2 for %s at %s\n",my_progname,SYSTEM_TYPE,
 	 MACHINE_TYPE);
   if (version)
     return;
@@ -50,6 +52,9 @@ static void usage(my_bool version)
   printf("\n\
   -c, --config-file=#, --defaults-file=#\n\
 	                The config file to use (default '%s')\n\
+  -e, --extra-file=#, --defaults-extra-file=#\n\
+			Read this file after the global /etc config file and\n\
+			before the config file in the users home directory.\n\
   --no-defaults		Return an empty string (useful for scripts)\n\
   -?, --help		Display this help message and exit.\n\
   -V, --version		Output version information and exit.\n",
@@ -61,13 +66,16 @@ static int get_options(int *argc,char ***argv)
 {
   int c,option_index;
 
-  while ((c=getopt_long(*argc,*argv,"c:V?I",
+  while ((c=getopt_long(*argc,*argv,"c:e:V?I",
 			long_options, &option_index)) != EOF)
   {
     switch (c) {
     case 'c':
       config_file=optarg;
       break;
+    case 'e':
+      defaults_extra_file=optarg;		/* Used by the load_defaults */
+      break;
     case 'n':
       exit(0);
     case 'I':
@@ -102,7 +110,7 @@ int main(int argc, char **argv)
   if (get_options(&argc,&argv))
     exit(1);
   if (!(load_default_groups=(char**) my_malloc((argc+2)*sizeof(char*),
-					      MYF(MY_WME))))
+					       MYF(MY_WME))))
     exit(1);
 
   for (count=0; *argv ; argv++,count++)

include/my_sys.h

@@ -206,6 +206,7 @@ extern my_bool NEAR my_disable_locking,NEAR my_disable_async_io,
        NEAR my_disable_flush_key_blocks;
 extern char	wild_many,wild_one,wild_prefix;
 extern const char *charsets_dir;
+extern char *defaults_extra_file;
 
 typedef struct wild_file_pack	/* Struct to hold info when selecting files */
 {

mysys/default.c

@@ -29,8 +29,9 @@
 ** The following arguments are handled automaticly;  If used, they must be
 ** first argument on the command line!
 ** --no-defaults	; no options are read.
-** --print-defaults	; Print the modified command line and exit
 ** --defaults-file=full-path-to-default-file	; Only this file will be read.
+** --defaults-extra-file=full-path-to-default-file ; Read this file before ~/
+** --print-defaults	; Print the modified command line and exit
 ****************************************************************************/
 
 #undef SAFEMALLOC		/* safe_malloc is not yet initailized */
@@ -39,6 +40,8 @@
 #include "m_string.h"
 #include "m_ctype.h"
 
+char *defaults_extra_file=0;
+
 /* Which directories are searched for options (and in which order) */
 
 const char *default_directories[]= {
@@ -50,6 +53,7 @@ const char *default_directories[]= {
 #ifdef DATADIR
 DATADIR,
 #endif
+"",					/* Place for defaults_extra_dir */
 #ifndef __WIN__
 "~/",
 #endif
@@ -71,9 +75,10 @@ void load_defaults(const char *conf_file, const char **groups,
 		   int *argc, char ***argv)
 {
   DYNAMIC_ARRAY args;
-  const char **dirs, *extra_default_file;
+  const char **dirs, *forced_default_file;
   TYPELIB group;
   my_bool found_print_defaults=0;
+  uint args_used=0;
   MEM_ROOT alloc;
   char *ptr,**res;
   DBUG_ENTER("load_defaults");
@@ -97,9 +102,20 @@ void load_defaults(const char *conf_file, const char **groups,
   }
 
   /* Check if we want to force the use a specific default file */
-  extra_default_file=0;
+  forced_default_file=0;
-  if (*argc >= 2 && is_prefix(argv[0][1],"--defaults-file="))
+  if (*argc >= 2)
-    extra_default_file=strchr(argv[0][1],'=')+1;
+  {
+    if (is_prefix(argv[0][1],"--defaults-file="))
+    {
+      forced_default_file=strchr(argv[0][1],'=')+1;
+      args_used++;
+    }
+    else if (is_prefix(argv[0][1],"--defaults-extra-file="))
+    {
+      defaults_extra_file=strchr(argv[0][1],'=')+1;
+      args_used++;
+    }
+  }
 
   group.count=0;
   group.name= "defaults";
@@ -109,9 +125,9 @@ void load_defaults(const char *conf_file, const char **groups,
 
   if (init_dynamic_array(&args, sizeof(char*),*argc, 32))
     goto err;
-  if (extra_default_file)
+  if (forced_default_file)
   {
-    if (search_default_file(&args, &alloc, "", extra_default_file, "",
+    if (search_default_file(&args, &alloc, "", forced_default_file, "",
 			    &group))
       goto err;
   }
@@ -132,8 +148,14 @@ void load_defaults(const char *conf_file, const char **groups,
 #endif
     for (dirs=default_directories ; *dirs; dirs++)
     {
-      if (search_default_file(&args, &alloc, *dirs, conf_file, default_ext,
+      int error;
-			      &group))
+      if (**dirs)
+	error=search_default_file(&args, &alloc, *dirs, conf_file,
+				  default_ext, &group);
+      else if (defaults_extra_file)
+	error=search_default_file(&args, &alloc, NullS, defaults_extra_file,
+				  default_ext, &group);
+      if (error)
 	goto err;
     }
   }
@@ -145,11 +167,9 @@ void load_defaults(const char *conf_file, const char **groups,
   /* copy name + found arguments + command line arguments to new array */
   res[0]=argv[0][0];
   memcpy((gptr) (res+1), args.buffer, args.elements*sizeof(char*));
-  if (extra_default_file)
+  /* Skipp --defaults-file and --defaults-extra-file */
-  {
+  (*argc)-= args_used;
-    --*argc;					/* Skipp --defaults-file */
+  (*argv)+= args_used;
-    ++*argv;
-  }
 
   /* Check if we wan't to see the new argument list */
   if (*argc >= 2 && !strcmp(argv[0][1],"--print-defaults"))

sql/sql_acl.cc

@@ -2004,6 +2004,8 @@ bool check_grant(THD *thd, uint want_access, TABLE_LIST *tables,
       want_access &= ~table->grant.privilege;
       goto err;					// No grants
     }
+    if (show_table)
+      continue;					// We have some priv on this
 
     table->grant.grant_table=grant_table;	// Remember for column test
     table->grant.version=grant_version;
@@ -2013,8 +2015,6 @@ bool check_grant(THD *thd, uint want_access, TABLE_LIST *tables,
 
     if (!(~table->grant.privilege & want_access))
       continue;
-    if (show_table && table->grant.privilege)
-      continue;					// Test from show tables
 
     if (want_access & ~(grant_table->cols | table->grant.privilege))
     {
@@ -2457,18 +2457,18 @@ int mysql_show_grants(THD *thd,LEX_USER *lex_user)
 	!strcmp(lex_user->host.str,host))
     {
       want_access=grant_table->privs;
-      if (want_access) 
+      if ((want_access | grant_table->cols) != 0)
       {
 	String global(buff,sizeof(buff));
 	global.length(0);
 	global.append("GRANT ",6);
 
-	if (test_all_bits(want_access,(TABLE_ACLS & ~GRANT_ACL)))
+	if (test_all_bits(grant_table->privs,(TABLE_ACLS & ~GRANT_ACL)))
 	  global.append("ALL PRIVILEGES",14);
 	else 
 	{
 	  int found=0;
-	  uint j,test_access= want_access & ~GRANT_ACL;
+	  uint j,test_access= (want_access | grant_table->cols) & ~GRANT_ACL;
 
 	  for (counter=0, j = SELECT_ACL;j <= TABLE_ACLS; counter++,j <<= 1)
 	  {

sql/sql_select.cc

@@ -136,7 +136,8 @@ static void copy_sum_funcs(Item_sum **func_ptr);
 static bool add_ref_to_table_cond(THD *thd, JOIN_TAB *join_tab);
 static void init_sum_functions(Item_sum **func);
 static bool update_sum_func(Item_sum **func);
-static void select_describe(JOIN *join, bool need_tmp_table, bool need_order);
+static void select_describe(JOIN *join, bool need_tmp_table, bool need_order,
+			    bool distinct);
 static void describe_info(const char *info);
 
 /*****************************************************************************
@@ -171,6 +172,7 @@ mysql_select(THD *thd,TABLE_LIST *tables,List<Item> &fields,COND *conds,
   no_order=0;
   bzero((char*) &keyuse,sizeof(keyuse));
   thd->proc_info="init";
+  thd->used_tables=0;				// Updated by setup_fields
 
   if (setup_fields(thd,tables,fields,1,&all_fields) ||
       setup_conds(thd,tables,&conds) ||
@@ -261,7 +263,7 @@ mysql_select(THD *thd,TABLE_LIST *tables,List<Item> &fields,COND *conds,
   join.join_tab=0;
   join.tmp_table_param.copy_field=0;
   join.sum_funcs=0;
-  join.send_records=0L;
+  join.send_records=join.found_records=0;
   join.tmp_table_param.end_write_records= HA_POS_ERROR;
   join.first_record=join.sort_and_group=0;
   join.select_options=select_options;
@@ -506,7 +508,8 @@ mysql_select(THD *thd,TABLE_LIST *tables,List<Item> &fields,COND *conds,
       order=0;
     select_describe(&join,need_tmp,
 		    (order != 0 &&
-		     (!need_tmp || order != group || simple_group)));
+		     (!need_tmp || order != group || simple_group)),
+		    select_distinct);
     error=0;
     goto err;
   }
@@ -557,6 +560,26 @@ mysql_select(THD *thd,TABLE_LIST *tables,List<Item> &fields,COND *conds,
 	order=0;
       }
     }
+
+    /*
+      Optimize distinct when used on some of the tables
+      SELECT DISTINCT t1.a FROM t1,t2 WHERE t1.b=t2.b
+      In this case we can stop scanning t2 when we have found one t1.a
+    */
+
+    if (tmp_table->distinct)
+    {
+      table_map used_tables= thd->used_tables;
+      JOIN_TAB *join_tab=join.join_tab+join.tables-1;
+      do
+      {
+	if (used_tables & join_tab->table->map)
+	  break;
+	join_tab->not_used_in_distinct=1;
+      } while (join_tab-- != join.join_tab);
+    }
+
+    /* Copy data to the temporary table */
     thd->proc_info="Copying to tmp table";
     if (do_select(&join,(List<Item> *) 0,tmp_table,0))
       goto err;					/* purecov: inspected */
@@ -2122,7 +2145,7 @@ make_simple_join(JOIN *join,TABLE *tmp_table)
   join->tmp_table_param.copy_field=0;
   join->first_record=join->sort_and_group=0;
   join->sum_funcs=0;
-  join->send_records=0L;
+  join->send_records=(ha_rows) 0;
   join->group=0;
 
   join_tab->cache.buff=0;			/* No cacheing */
@@ -2130,15 +2153,16 @@ make_simple_join(JOIN *join,TABLE *tmp_table)
   join_tab->select=0;
   join_tab->select_cond=0;
   join_tab->quick=0;
-  bzero((char*) &join_tab->read_record,sizeof(join_tab->read_record));
   join_tab->type= JT_ALL;			/* Map through all records */
   join_tab->keys= (uint) ~0;			/* test everything in quick */
   join_tab->info=0;
   join_tab->on_expr=0;
   join_tab->ref.key = -1;
+  join_tab->not_used_in_distinct=0;
+  join_tab->read_first_record= join_init_read_record;
+  bzero((char*) &join_tab->read_record,sizeof(join_tab->read_record));
   tmp_table->status=0;
   tmp_table->null_row=0;
-  join_tab->read_first_record= join_init_read_record;
   return FALSE;
 }
 
@@ -3256,7 +3280,6 @@ create_tmp_table(THD *thd,TMP_TABLE_PARAM *param,List<Item> &fields,
     if (item->with_sum_func && type != Item::SUM_FUNC_ITEM ||
 	item->const_item())
       continue;
-
     if (type == Item::SUM_FUNC_ITEM && !group && !save_sum_fields)
     {						/* Can't calc group yet */
       ((Item_sum*) item)->result_field=0;
@@ -3913,7 +3936,9 @@ sub_select(JOIN *join,JOIN_TAB *join_tab,bool end_of_records)
 
   if (!(error=(*join_tab->read_first_record)(join_tab)))
   {
-    bool not_exists_optimize=join_tab->table->reginfo.not_exists_optimize;
+    bool not_exists_optimize= join_tab->table->reginfo.not_exists_optimize;
+    bool not_used_in_distinct=join_tab->not_used_in_distinct;
+    ha_rows found_records=join->found_records;
     READ_RECORD *info= &join_tab->read_record;
 
     do
@@ -3932,6 +3957,8 @@ sub_select(JOIN *join,JOIN_TAB *join_tab,bool end_of_records)
 	{
 	  if ((error=(*next_select)(join,join_tab+1,0)) < 0)
 	    return error;
+	  if (not_used_in_distinct && found_records != join->found_records)
+	    return 0;
 	}
       }
     } while (!(error=info->read_record(info)));
@@ -4545,23 +4572,21 @@ end_write(JOIN *join, JOIN_TAB *join_tab __attribute__((unused)),
     }
     if (!join->having || join->having->val_int())
     {
+      join->found_records++;
       if ((error=table->file->write_row(table->record[0])))
       {
-	if (error != HA_ERR_FOUND_DUPP_KEY &&
+	if (error == HA_ERR_FOUND_DUPP_KEY ||
-	    error != HA_ERR_FOUND_DUPP_UNIQUE)
+	    error == HA_ERR_FOUND_DUPP_UNIQUE)
-	{
+	  goto end;
-	  if (create_myisam_from_heap(table, &join->tmp_table_param, error,1))
+	if (create_myisam_from_heap(table, &join->tmp_table_param, error,1))
-	    DBUG_RETURN(1);			// Not a table_is_full error
+	  DBUG_RETURN(1);			// Not a table_is_full error
-	  table->uniques=0;			// To ensure rows are the same
+	table->uniques=0;			// To ensure rows are the same
-	}
-      }
-      else
-      {
 	if (++join->send_records >= join->tmp_table_param.end_write_records)
 	  DBUG_RETURN(-3);
       }
     }
   }
+end:
   DBUG_RETURN(0);
 }
 
@@ -4585,6 +4610,7 @@ end_update(JOIN *join, JOIN_TAB *join_tab __attribute__((unused)),
     DBUG_RETURN(-2);				/* purecov: inspected */
   }
 
+  join->found_records++;
   copy_fields(&join->tmp_table_param);		// Groups are copied twice.
   /* Make a key of group index */
   for (group=table->group ; group ; group=group->next)
@@ -6335,12 +6361,13 @@ static bool add_ref_to_table_cond(THD *thd, JOIN_TAB *join_tab)
 ** Send a description about what how the select will be done to stdout
 ****************************************************************************/
 
-static void select_describe(JOIN *join, bool need_tmp_table, bool need_order)
+static void select_describe(JOIN *join, bool need_tmp_table, bool need_order,
+			    bool distinct)
 {
-  DBUG_ENTER("select_describe");
-
   List<Item> field_list;
   Item *item;
+  THD *thd=join->thd;
+  DBUG_ENTER("select_describe");
 
   field_list.push_back(new Item_empty_string("table",NAME_LEN));
   field_list.push_back(new Item_empty_string("type",10));
@@ -6356,11 +6383,12 @@ static void select_describe(JOIN *join, bool need_tmp_table, bool need_order)
   item->maybe_null=1;
   field_list.push_back(new Item_real("rows",0.0,0,10));
   field_list.push_back(new Item_empty_string("Extra",255));
-  if (send_fields(join->thd,field_list,1))
+  if (send_fields(thd,field_list,1))
     return; /* purecov: inspected */
 
   char buff[512],*buff_ptr;
-  String tmp(buff,sizeof(buff)),*packet= &join->thd->packet;
+  String tmp(buff,sizeof(buff)),*packet= &thd->packet;
+  table_map used_tables=0;
   for (uint i=0 ; i < join->tables ; i++)
   {
     JOIN_TAB *tab=join->join_tab+i;
@@ -6473,11 +6501,22 @@ static void select_describe(JOIN *join, bool need_tmp_table, bool need_order)
       }
       buff_ptr=strmov(buff_ptr,"Using filesort");
     }
+    if (distinct & test_all_bits(used_tables,thd->used_tables))
+    {
+      if (buff != buff_ptr)
+      {
+	buff_ptr[0]=';' ; buff_ptr[1]=' '; buff_ptr+=2;
+      }
+      buff_ptr=strmov(buff_ptr,"Distinct");
+    }
     net_store_data(packet,buff,(uint) (buff_ptr - buff));
-    if (my_net_write(&join->thd->net,(char*) packet->ptr(),packet->length()))
+    if (my_net_write(&thd->net,(char*) packet->ptr(),packet->length()))
       DBUG_VOID_RETURN;				/* purecov: inspected */
+
+    // For next iteration
+    used_tables|=table->map;
   }
-  send_eof(&join->thd->net);
+  send_eof(&thd->net);
   DBUG_VOID_RETURN;
 }
 

sql/sql_select.h

@@ -79,36 +79,36 @@ class JOIN;
 
 typedef struct st_join_table {
   TABLE		*table;
-  int		(*read_first_record)(struct st_join_table *tab);
-  int		(*next_select)(JOIN *,struct st_join_table *,bool);
-  bool		cached_eq_ref_table,eq_ref_table;
-  READ_RECORD	read_record;
-  uint		keys;				/* all keys with can be used */
-  key_map	const_keys;			/* Keys with constant part */
-  key_map	checked_keys;			/* Keys checked in find_best */
-  key_map	needed_reg;
-  ha_rows	records,found_records,read_time;
-  table_map	dependent,key_dependent;
-  uint		use_quick,index;
-  uint		status;				// Save status for cache
-  enum join_type type;
-  JOIN_CACHE	cache;
   KEYUSE	*keyuse;			/* pointer to first used key */
   SQL_SELECT	*select;
   COND		*select_cond;
   QUICK_SELECT	*quick;
   Item		*on_expr;
-  uint		used_fields,used_fieldlength,used_blobs;
   const char	*info;
+  int		(*read_first_record)(struct st_join_table *tab);
+  int		(*next_select)(JOIN *,struct st_join_table *,bool);
+  READ_RECORD	read_record;
   double	worst_seeks;
+  key_map	const_keys;			/* Keys with constant part */
+  key_map	checked_keys;			/* Keys checked in find_best */
+  key_map	needed_reg;
+  ha_rows	records,found_records,read_time;
+  table_map	dependent,key_dependent;
+  uint		keys;				/* all keys with can be used */
+  uint		use_quick,index;
+  uint		status;				// Save status for cache
+  uint		used_fields,used_fieldlength,used_blobs;
+  enum join_type type;
+  bool		cached_eq_ref_table,eq_ref_table,not_used_in_distinct;
   TABLE_REF	ref;
+  JOIN_CACHE	cache;
 } JOIN_TAB;
 
 
 typedef struct st_position {			/* Used in find_best */
+  double records_read;
   JOIN_TAB *table;
   KEYUSE *key;
-  double records_read;
 } POSITION;
 
 
@@ -116,16 +116,16 @@ typedef struct st_position {			/* Used in find_best */
 
 class TMP_TABLE_PARAM {
  public:
+  List<Item> copy_funcs;
+  Copy_field *copy_field;
+  byte	    *group_buff;
+  Item_result_field **funcs;
+  MI_COLUMNDEF *recinfo,*start_recinfo;
+  KEY *keyinfo;
+  ha_rows end_write_records;
   uint	copy_field_count,field_count,sum_func_count,func_count;
   uint	group_parts,group_length;
   uint	quick_group;
-  Copy_field *copy_field;
-  byte	    *group_buff;
-  ha_rows end_write_records;
-  Item_result_field **funcs;
-  List<Item> copy_funcs;
-  MI_COLUMNDEF *recinfo,*start_recinfo;
-  KEY *keyinfo;
 
   TMP_TABLE_PARAM() :group_parts(0),group_length(0),copy_field(0) {}
   ~TMP_TABLE_PARAM()
@@ -148,7 +148,7 @@ class JOIN {
   uint	   send_group_parts;
   bool	   sort_and_group,first_record,full_join,group, no_field_update;
   table_map const_table_map;
-  ha_rows  send_records;
+  ha_rows  send_records,found_records;
   POSITION positions[MAX_TABLES+1],best_positions[MAX_TABLES+1];
   double   best_read;
   List<Item> *fields;