Reduce index key size on el6

zabbix.spec

@@ -480,6 +480,12 @@ gzip database/postgresql/create.sql
 gzip database/postgresql/timescaledb.sql
 
 # sql files for proxyes
+%if 0%{?rhel} == 6
+# MySQL on el6 doesn't support such large  keys
+sed -i -e \
+  's/CREATE INDEX `items_1` ON `items` (`hostid`,`key_`(1021));/CREATE INDEX `items_1` ON `items` (`hostid`,`key_`(900));/' \
+  database/mysql/schema.sql
+%endif
 gzip database/mysql/schema.sql
 gzip database/postgresql/schema.sql
 gzip database/sqlite3/schema.sql