Added FLUSH THREADS

mysql-test/main/flush.result

@@ -558,3 +558,10 @@ ERROR HY000: Table 'v1' was not locked with LOCK TABLES
 UNLOCK TABLES;
 DROP VIEW v1;
 DROP TABLE t1;
+#
+# Test FLUSH THREADS
+#
+flush threads;
+show status like "Threads_cached";
+Variable_name	Value
+Threads_cached	0

mysql-test/main/flush.test

@@ -672,3 +672,9 @@ UNLOCK TABLES;
 DROP VIEW v1;
 DROP TABLE t1;
 
+--echo #
+--echo # Test FLUSH THREADS
+--echo #
+
+flush threads;
+show status like "Threads_cached";

mysql-test/suite/perfschema/r/start_server_low_digest_sql_length.result

@@ -8,5 +8,5 @@ SELECT 1+1+1+1+1+1+1+1+1+1+1+1+1+1+1+1+1+1+1+1+1+1+1+1+1+1+1+1+1+1+1+1+1+1+1+1+1
 ####################################
 SELECT event_name, digest, digest_text, sql_text FROM events_statements_history_long;
 event_name	digest	digest_text	sql_text
-statement/sql/truncate	1ce0abbaf6f3f120bdc1464f34c3e614	TRUNCATE TABLE 	truncat...
-statement/sql/select	c13037c37462abf2be6cf94058702f18	SELECT ? + ? + 	SELECT ...
+statement/sql/select	8ad134e475b278738ee855a05d6a77cf	SELECT ? + ? + 	SELECT ...
+statement/sql/truncate	2b32156b59f41d61d9070458bce5932e	TRUNCATE TABLE 	truncat...

mysql-test/suite/perfschema/t/start_server_low_digest_sql_length.test

@@ -19,4 +19,5 @@ SELECT 1+1+1+1+1+1+1+1+1+1+1+1+1+1+1+1+1+1+1+1+1+1+1+1+1+1+1+1+1+1+1+1+1+1+1+1+1
 --echo ####################################
 --echo # QUERYING PS STATEMENT DIGEST
 --echo ####################################
+--sorted_result
 SELECT event_name, digest, digest_text, sql_text FROM events_statements_history_long;

sql/lex.h

@@ -661,6 +661,7 @@ static SYMBOL symbols[] = {
   { "TRAILING",		SYM(TRAILING)},
   { "TRANSACTION",	SYM(TRANSACTION_SYM)},
   { "TRANSACTIONAL",	SYM(TRANSACTIONAL_SYM)},
+  { "THREADS",          SYM(THREADS_SYM)},
   { "TRIGGER",          SYM(TRIGGER_SYM)},
   { "TRIGGERS",         SYM(TRIGGERS_SYM)},
   { "TRUE",		SYM(TRUE_SYM)},

sql/sql_yacc.yy

@@ -1098,6 +1098,7 @@ End SQL_MODE_ORACLE_SPECIFIC */
 %token  <kwd>  TIME_SYM                      /* SQL-2003-R, Oracle-R */
 %token  <kwd>  TRANSACTION_SYM
 %token  <kwd>  TRANSACTIONAL_SYM
+%token  <kwd>  THREADS_SYM
 %token  <kwd>  TRIGGERS_SYM
 %token  <kwd>  TRIM_ORACLE
 %token  <kwd>  TRUNCATE_SYM
@@ -14085,6 +14086,8 @@ flush_option:
           { Lex->type|= REFRESH_USER_RESOURCES; }
         | SSL_SYM
           { Lex->type|= REFRESH_SSL;}
+        | THREADS_SYM
+          { Lex->type|= REFRESH_THREADS;}        
         | IDENT_sys remember_tok_start
            {
              Lex->type|= REFRESH_GENERIC;
@@ -15741,6 +15744,7 @@ keyword_sp_var_and_label:
         | THAN_SYM
         | TRANSACTION_SYM    %prec PREC_BELOW_CONTRACTION_TOKEN2
         | TRANSACTIONAL_SYM
+        | THREADS_SYM
         | TRIGGERS_SYM
         | TRIM_ORACLE
         | TIMESTAMP_ADD