From 6bbcaba7ff7732cfbca43a92a72d937c87d55796 Mon Sep 17 00:00:00 2001
From: Dan Stillman <dstillman@zotero.org>
Date: Tue, 16 Jun 2026 15:54:57 -0400
Subject: [PATCH] Use one combined tag query for a multiple-row selection

---
 .../containers/tagSelectorContainer.jsx       |  9 +++--
 .../content/zotero/xpcom/collectionTreeRow.js | 34 +++++++++++++++++++
 2 files changed, 40 insertions(+), 3 deletions(-)

diff --git a/chrome/content/zotero/containers/tagSelectorContainer.jsx b/chrome/content/zotero/containers/tagSelectorContainer.jsx
index 5f948bb209..a1a2cfc382 100644
--- a/chrome/content/zotero/containers/tagSelectorContainer.jsx
+++ b/chrome/content/zotero/containers/tagSelectorContainer.jsx
@@ -130,9 +130,12 @@ Zotero.TagSelector = class TagSelectorContainer extends React.PureComponent {
 	 */
 	async _safeGetTags(...args) {
 		try {
-			let tags = (await Promise.all(
-				this.collectionTreeRows.map(row => row.getTags(...args))
-			)).flat();
+			let rows = this.collectionTreeRows || [];
+			// A single row uses its own cached temp table directly; multiple rows are
+			// combined into one temp table and query to avoid a per-row query
+			let tags = rows.length == 1
+				? await rows[0].getTags(...args)
+				: await Zotero.CollectionTreeRow.getTagsAcrossRows(rows, ...args);
 			// Multiple rows (collections, or collections across libraries) can return
 			// the same tag, so dedupe by name
 			return this._dedupeTags(tags);
diff --git a/chrome/content/zotero/xpcom/collectionTreeRow.js b/chrome/content/zotero/xpcom/collectionTreeRow.js
index b7595b2fbb..d47a7449ed 100644
--- a/chrome/content/zotero/xpcom/collectionTreeRow.js
+++ b/chrome/content/zotero/xpcom/collectionTreeRow.js
@@ -567,6 +567,40 @@ Zotero.CollectionTreeRow.prototype.getTags = async function (types, tagIDs) {
 };
 
 
+/**
+ * Returns all the tags used by items across multiple rows' views
+ *
+ * Combines the rows' search results into a single temporary table and runs one tag
+ * query, rather than creating a temp table and running a separate query per row.
+ *
+ * @param {Zotero.CollectionTreeRow[]} rows
+ * @param {Number[]} [types]
+ * @param {Number[]} [tagIDs]
+ * @return {Promise<Object[]>}
+ */
+Zotero.CollectionTreeRow.getTagsAcrossRows = async function (rows, types, tagIDs) {
+	// share/bucket/feeds rows never contribute tags (see getTags())
+	var tagRows = rows.filter(row => !['share', 'bucket', 'feeds'].includes(row.type));
+	if (!tagRows.length) {
+		return [];
+	}
+	// Combine the rows' search results into a single set of item IDs
+	var itemIDs = new Set();
+	for (let ids of await Promise.all(tagRows.map(row => row.getSearchResults(false)))) {
+		for (let id of ids) {
+			itemIDs.add(id);
+		}
+	}
+	var tmpTable = await Zotero.Search.idsToTempTable([...itemIDs]);
+	try {
+		return await Zotero.Tags.getAllWithin({ tmpTable, types, tagIDs });
+	}
+	finally {
+		await Zotero.DB.queryAsync(`DROP TABLE IF EXISTS ${tmpTable}`, false, { noCache: true });
+	}
+};
+
+
 /**
  * Clear the per-instance search cache. Call this at the start of a refresh cycle
  * or when search/tag filters change, so the next getSearchResults()/getSearchObject()