Disable info_schema.tables collector by default (#406)

`info_schema.tables` has a danger of excessive cardinality, disable by
default.

Signed-off-by: Ben Kochie <superq@gmail.com>

Author: SuperQ

CHANGELOG.md

@@ -4,6 +4,8 @@
 
 The minimum supported MySQL version is now 5.5.
 
+Collector `info_schema.tables` is now disabled by default due to high cardinality danger.
+
 ### Changes:
 
 * [CHANGE]
@@ -13,6 +15,7 @@ The minimum supported MySQL version is now 5.5.
 
 * [CHANGE] Update innodb buffer pool mappings #369 
 * [CHANGE] Update defaults for MySQL 5.5 #318
+* [CHANGE] Disable info_schema.tables collector by default #406
 * [BUGFIX] Sanitize metric names in global variables #307
 * [BUGFIX] Clear last_scrape_error on every scrape (PR #368) #367
 * [FEATURE] Add by_user and by_host metrics to info_schema.processlist collector (PR #333) #334

mysqld_exporter.go

@@ -63,7 +63,7 @@ var scrapers = map[collector.Scraper]bool{
 	collector.ScrapeSlaveStatus{}:                         true,
 	collector.ScrapeProcesslist{}:                         false,
 	collector.ScrapeUser{}:                                false,
-	collector.ScrapeTableSchema{}:                         true,
+	collector.ScrapeTableSchema{}:                         false,
 	collector.ScrapeInfoSchemaInnodbTablespaces{}:         false,
 	collector.ScrapeInnodbMetrics{}:                       false,
 	collector.ScrapeAutoIncrementColumns{}:                false,