From 53956084fee739a9043f80afc2ec481686825b2a Mon Sep 17 00:00:00 2001
From: Manfred Stienstra <manfred@fngtps.com>
Date: Wed, 19 Nov 2008 15:17:40 +0100
Subject: [PATCH] Free MySQL::Result objects after a call to execute.

No freeing Result objects causes the MySQL driver to free result sets
at undefined times, this can lead to erratic performance in your
application.
---
 .../connection_adapters/mysql_adapter.rb           |   17 +++++++++++++----
 1 files changed, 13 insertions(+), 4 deletions(-)

diff --git a/activerecord/lib/active_record/connection_adapters/mysql_adapter.rb b/activerecord/lib/active_record/connection_adapters/mysql_adapter.rb
index 1e452ae..8668475 100644
--- a/activerecord/lib/active_record/connection_adapters/mysql_adapter.rb
+++ b/activerecord/lib/active_record/connection_adapters/mysql_adapter.rb
@@ -305,6 +305,7 @@ module ActiveRecord
         rows
       end
 
+      # Executes a SQL query and returns a MySQL::Result object. Note that you have to free the Result object after you're done using it.
       def execute(sql, name = nil) #:nodoc:
         log(sql, name) { @connection.query(sql) }
       rescue ActiveRecord::StatementInvalid => exception
@@ -411,7 +412,9 @@ module ActiveRecord
 
       def tables(name = nil) #:nodoc:
         tables = []
-        execute("SHOW TABLES", name).each { |field| tables << field[0] }
+        result = execute("SHOW TABLES", name)
+        result.each { |field| tables << field[0] }
+        result.free
         tables
       end
 
@@ -422,7 +425,8 @@ module ActiveRecord
       def indexes(table_name, name = nil)#:nodoc:
         indexes = []
         current_index = nil
-        execute("SHOW KEYS FROM #{quote_table_name(table_name)}", name).each do |row|
+        result = execute("SHOW KEYS FROM #{quote_table_name(table_name)}", name)
+        result.each do |row|
           if current_index != row[2]
             next if row[2] == "PRIMARY" # skip the primary key
             current_index = row[2]
@@ -431,13 +435,16 @@ module ActiveRecord
 
           indexes.last.columns << row[4]
         end
+        result.free
         indexes
       end
 
       def columns(table_name, name = nil)#:nodoc:
         sql = "SHOW FIELDS FROM #{quote_table_name(table_name)}"
         columns = []
-        execute(sql, name).each { |field| columns << MysqlColumn.new(field[0], field[4], field[1], field[2] == "YES") }
+        result = execute(sql, name)
+        result.each { |field| columns << MysqlColumn.new(field[0], field[4], field[1], field[2] == "YES") }
+        result.free
         columns
       end
 
@@ -518,9 +525,11 @@ module ActiveRecord
       # Returns a table's primary key and belonging sequence.
       def pk_and_sequence_for(table) #:nodoc:
         keys = []
-        execute("describe #{quote_table_name(table)}").each_hash do |h|
+        result = execute("describe #{quote_table_name(table)}")
+        result.each_hash do |h|
           keys << h["Field"]if h["Key"] == "PRI"
         end
+        result.free
         keys.length == 1 ? [keys.first, nil] : nil
       end
 
-- 
1.6.0.2