From 143b80b3a6d6a13f7d0a5f271b4e59ffbf223b7e Mon Sep 17 00:00:00 2001
From: Jean-Marie Renouard <jmrenouard@gmail.com>
Date: Thu, 3 Oct 2019 21:29:03 +0200
Subject: [PATCH] Add recommendation on table_definition_cache #433

---
 INTERNALS.md  |  1 +
 mysqltuner.pl | 17 +++++++++++++++++
 2 files changed, 18 insertions(+)

diff --git a/INTERNALS.md b/INTERNALS.md
index aa6121f..9f2090b 100644
--- a/INTERNALS.md
+++ b/INTERNALS.md
@@ -167,6 +167,7 @@
 * Thread cache (=4)
 * Thread cache hit ratio (>50%) if thread_handling is different of pools-of-threads
 * Table cache hit ratio(>2°%)
+* Table cache definition should be upper that total number of tables or in autoresizing mode
 * Percentage of open file and open file limit(<85%)
 * Percentage of table locks (<95%)
 * Percentage of binlog cache lock (<90%)
diff --git a/mysqltuner.pl b/mysqltuner.pl
index 48ba9d9..13ea9a6 100755
--- a/mysqltuner.pl
+++ b/mysqltuner.pl
@@ -3238,6 +3238,23 @@ sub mysql_stats {
         }
     }
 
+    # Table definition cache
+    my $nbtables=select_one('SELECT COUNT(*) FROM information_schema.tables');
+    if ( defined $myvar{'table_definition_cache'} ) {
+        if ( $myvar{'table_definition_cache'} == -1 ) {
+            infoprint ("table_definition_cache(".$myvar{'table_definition_cache'} .") is in autosizing mode");
+        } elsif ($myvar{'table_definition_cache'} < $nbtables ) {
+            badprint "table_definition_cache(".$myvar{'table_definition_cache'} .") is lower than number of tables($nbtables) ";
+            push( @adjvars,
+                "table_definition_cache(".$myvar{'table_definition_cache'} .") > " . $$nbtables . " or -1 (autosizing if supported)" );
+        }
+        else {
+            goodprint "table_definition_cache(".$myvar{'table_definition_cache'} .") is upper than number of tables($nbtables)";
+        }
+    } else {
+        infoprint "No table_definition_cache variable found.";
+    }
+
     # Open files
     if ( defined $mycalc{'pct_files_open'} ) {
         if ( $mycalc{'pct_files_open'} > 85 ) {