Adding Posts table indexes for 20M rows. (#7728)

store/sqlstore/post_store.go

@@ -11,6 +11,7 @@ import (
 	"strings"
 
 	"bytes"
+
 	l4g "github.com/alecthomas/log4go"
 	"github.com/mattermost/mattermost-server/einterfaces"
 	"github.com/mattermost/mattermost-server/model"
@@ -73,6 +74,9 @@ func (s SqlPostStore) CreateIndexesIfNotExists() {
 	s.CreateIndexIfNotExists("idx_posts_user_id", "Posts", "UserId")
 	s.CreateIndexIfNotExists("idx_posts_is_pinned", "Posts", "IsPinned")
 
+	s.CreateCompositeIndexIfNotExists("idx_posts_channel_id_update_at", "Posts", []string{"ChannelId", "UpdateAt"})
+	s.CreateCompositeIndexIfNotExists("idx_posts_channel_id_delete_at_create_at", "Posts", []string{"ChannelId", "DeleteAt", "CreateAt"})
+
 	s.CreateFullTextIndexIfNotExists("idx_posts_message_txt", "Posts", "Message")
 	s.CreateFullTextIndexIfNotExists("idx_posts_hashtags_txt", "Posts", "Hashtags")
 }