Add an index for going from a post to its replies

src/posts.js

@@ -260,4 +260,29 @@ var plugins = require('./plugins');
 		});
 	};
 
+	Posts.countReplies = function(pid, callback) {
+		if (Array.isArray(pid)) {
+			db.sortedSetsCard(pid.map(function (id) {
+				return 'pid:' + id + ':replies';
+			}), callback);
+		} else {
+			db.sortedSetCard('pid:' + pid + ':replies', callback);
+		}
+	};
+
+	Posts.getReplyPids = function(pid, callback) {
+		db.getSortedSetRange('pid:' + pid + ':replies', 0, -1, callback);
+	};
+
+	Posts.getReplyPosts = function(pid, uid, callback) {
+		async.waterfall([
+			function (next) {
+				Posts.getReplyPids(pid, next);
+			},
+			function (pids, next) {
+				Posts.getPostsByPids(pids, uid, next);
+			}
+		], callback);
+	};
+
 }(exports));

src/posts/create.js

@@ -82,6 +82,12 @@ module.exports = function (Posts) {
 					function (next) {
 						db.sortedSetAdd('posts:pid', timestamp, postData.pid, next);
 					},
+					function (next) {
+						if (!postData.toPid) {
+							return next(null);
+						}
+						db.sortedSetAdd('pid:' + postData.toPid + ':replies', timestamp, postData.pid, next);
+					},
 					function (next) {
 						db.incrObjectField('global', 'postCount', next);
 					}

src/posts/delete.js

@@ -137,6 +137,17 @@ module.exports = function (Posts) {
 					function (next) {
 						deletePostFromUsersVotes(pid, next);
 					},
+					function(next) {
+						Posts.getPostField(pid, 'toPid', function (err, toPid) {
+							if (err) {
+								return next(err);
+							}
+							if (!parseInt(toPid, 10)) {
+								return next(null);
+							}
+							db.sortedSetRemove('pid:' + toPid + ':replies', pid, next);
+						});
+					},
 					function (next) {
 						db.sortedSetsRemove(['posts:pid', 'posts:flagged'], pid, next);
 					},

src/upgrade.js

@@ -10,7 +10,7 @@ var db = require('./database'),
 	schemaDate, thisSchemaDate,
 
 	// IMPORTANT: REMEMBER TO UPDATE VALUE OF latestSchema
-	latestSchema = Date.UTC(2016, 9, 8);
+	latestSchema = Date.UTC(2016, 9, 14);
 
 Upgrade.check = function (callback) {
 	db.get('schemaDate', function (err, value) {
@@ -907,6 +907,41 @@ Upgrade.upgrade = function (callback) {
 				winston.info('[2016/10/8] favourite -> bookmark refactor - skipped!');
 				next();
 			}
+		},
+		function(next) {
+			thisSchemaDate = Date.UTC(2016, 9, 14);
+
+			if (schemaDate < thisSchemaDate) {
+				updatesMade = true;
+				winston.info('[2016/10/14] Creating sorted sets for post replies');
+
+				var posts = require('./posts');
+				var batch = require('./batch');
+				batch.processSortedSet('posts:pid', function(ids, next) {
+					posts.getPostsFields(ids, ['pid', 'toPid', 'timestamp'], function(err, data) {
+						if (err) {
+							return next(err);
+						}
+
+						async.each(data, function(postData, next) {
+							if (!parseInt(post.toPid, 10)) {
+								return next(null);
+							}
+							db.sortedSetAdd('pid:' + postData.toPid + ':replies', postData.timestamp, postData.pid, next);
+						}, next);
+					});
+				}, function(err) {
+					if (err) {
+						return next(err);
+					}
+
+					winston.info('[2016/10/14] Creating sorted sets for post replies - done');
+					Upgrade.update(thisSchemaDate, next);
+				});
+			} else {
+				winston.info('[2016/10/14] Creating sorted sets for post replies - skipped!');
+				next();
+			}
 		}
 		// Add new schema updates here
 		// IMPORTANT: REMEMBER TO UPDATE VALUE OF latestSchema IN LINE 24!!!