diff --git a/plugins/af_psql_trgm/init.php b/plugins/af_psql_trgm/init.php
new file mode 100644
index 00000000..a1ee040e
--- /dev/null
+++ b/plugins/af_psql_trgm/init.php
@@ -0,0 +1,202 @@
+<?php
+class Af_Psql_Trgm extends Plugin {
+
+	private $host;
+	private $filters = array();
+
+	function about() {
+		return array(1.0,
+			"Marks similar articles as read (requires pg_trgm)",
+			"fox");
+	}
+
+	function save() {
+		$similarity = (float) db_escape_string($_POST["similarity"]);
+		$min_title_length = (int) db_escape_string($_POST["min_title_length"]);
+
+		if ($similarity < 0) $similarity = 0;
+		if ($similarity > 1) $similarity = 1;
+
+		if ($min_title_length < 0) $min_title_length = 0;
+
+		$similarity = sprintf("%.2f", $similarity);
+
+		$this->host->set($this, "similarity", $similarity);
+		$this->host->set($this, "min_title_length", $min_title_length);
+
+		echo T_sprintf("Data saved (%s)", $similarity);
+	}
+
+	function init($host) {
+		$this->host = $host;
+
+		$host->add_hook($host::HOOK_ARTICLE_FILTER, $this);
+		$host->add_hook($host::HOOK_PREFS_TAB, $this);
+		$host->add_hook($host::HOOK_PREFS_EDIT_FEED, $this);
+		$host->add_hook($host::HOOK_PREFS_SAVE_FEED, $this);
+
+	}
+
+	function hook_prefs_tab($args) {
+		if ($args != "prefFeeds") return;
+
+		print "<div dojoType=\"dijit.layout.AccordionPane\" title=\"".__('Mark similar articles as read')."\">";
+
+		if (DB_TYPE != "pgsql") {
+			print_error("Database type not supported.");
+		}
+
+		$result = db_query("select 'similarity'::regproc");
+
+		if (db_num_rows($result) == 0) {
+			print_error("pg_trgm extension not found.");
+		}
+
+		$similarity = $this->host->get($this, "similarity");
+		$min_title_length = $this->host->get($this, "min_title_length");
+
+		if (!$similarity) $similarity = '0.75';
+		if (!$min_title_length) $min_title_length = '32';
+
+		print "<form dojoType=\"dijit.form.Form\">";
+
+		print "<script type=\"dojo/method\" event=\"onSubmit\" args=\"evt\">
+			evt.preventDefault();
+			if (this.validate()) {
+				console.log(dojo.objectToQuery(this.getValues()));
+				new Ajax.Request('backend.php', {
+					parameters: dojo.objectToQuery(this.getValues()),
+					onComplete: function(transport) {
+						notify_info(transport.responseText);
+					}
+				});
+				//this.reset();
+			}
+			</script>";
+
+		print "<input dojoType=\"dijit.form.TextBox\" style=\"display : none\" name=\"op\" value=\"pluginhandler\">";
+		print "<input dojoType=\"dijit.form.TextBox\" style=\"display : none\" name=\"method\" value=\"save\">";
+		print "<input dojoType=\"dijit.form.TextBox\" style=\"display : none\" name=\"plugin\" value=\"af_psql_trgm\">";
+
+		print_notice("PostgreSQL trigram extension returns string similarity as a floating point number (0-1). Setting it too low might produce false positives, zero disables checking.");
+
+		print "<br/>";
+		print_notice("Only data in other feeds is checked, i.e. sequential duplicate posts in one feed will not be detected by this plugin.");
+
+		print "<br/>";
+		print_notice("Enable the plugin for specific feeds in the feed editor.");
+
+		print "<h3>" . __("Global settings") . "</h3>";
+
+		print "<table>";
+
+		print "<tr><td width=\"40%\">".__("Minimum similarity:")."</td>";
+		print "<td>
+			<input dojoType=\"dijit.form.ValidationTextBox\"
+			placeholder=\"0.75\"
+			required=\"1\" name=\"similarity\" value=\"$similarity\"></td></tr>";
+		print "<tr><td width=\"40%\">".__("Minimum title length:")."</td>";
+		print "<td>
+			<input dojoType=\"dijit.form.ValidationTextBox\"
+			placeholder=\"32\"
+			required=\"1\" name=\"min_title_length\" value=\"$min_title_length\"></td></tr>";
+
+
+		print "</table>";
+
+		print "<p><button dojoType=\"dijit.form.Button\" type=\"submit\">".
+			__("Save")."</button>";
+
+		print "</form>";
+
+		print "</div>";
+	}
+
+	//PluginHost::getInstance()->run_hooks(PluginHost::HOOK_PREFS_EDIT_FEED,
+	//		"hook_prefs_edit_feed", $feed_id);
+	//	PluginHost::getInstance()->run_hooks(PluginHost::HOOK_PREFS_SAVE_FEED,
+	//		"hook_prefs_save_feed", $feed_id);
+
+	function hook_prefs_edit_feed($feed_id) {
+		print "<div class=\"dlgSec\">".__("Similarity (pg_trgm)")."</div>";
+		print "<div class=\"dlgSecCont\">";
+
+		$enabled_feeds = $this->host->get($this, "enabled_feeds");
+		if (!array($enabled_feeds)) $enabled_feeds = array();
+
+		$key = array_search($feed_id, $enabled_feeds);
+		$checked = $key !== FALSE ? "checked" : "";
+
+		print "<hr/><input dojoType=\"dijit.form.CheckBox\" type=\"checkbox\" id=\"trgm_similarity_enabled\"
+			name=\"trgm_similarity_enabled\"
+			$checked>&nbsp;<label for=\"trgm_similarity_enabled\">".__('Mark similar articles as read')."</label>";
+
+		print "</div>";
+	}
+
+	function hook_prefs_save_feed($feed_id) {
+		$enabled_feeds = $this->host->get($this, "enabled_feeds");
+		if (!is_array($enabled_feeds)) $enabled_feeds = array();
+
+		$enable = checkbox_to_sql_bool($_POST["trgm_similarity_enabled"]) == 'true';
+		$key = array_search($feed_id, $enabled_feeds);
+
+		if ($enable) {
+			if ($key === FALSE) {
+				array_push($enabled_feeds, $feed_id);
+			}
+		} else {
+			if ($key !== FALSE) {
+				unset($enabled_feeds[$key]);
+			}
+		}
+
+		$this->host->set($this, "enabled_feeds", $enabled_feeds);
+	}
+
+	function hook_article_filter($article) {
+
+		if (DB_TYPE != "pgsql") return $article;
+
+		$result = db_query("select 'similarity'::regproc");
+		if (db_num_rows($result) == 0) return $article;
+
+		$enabled_feeds = $this->host->get($this, "enabled_feeds");
+		$key = array_search($article["feed"]["id"], $enabled_feeds);
+		if ($key === FALSE) return $article;
+
+		$similarity = (float) $this->host->get($this, "similarity");
+		if ($similarity < 0.01) return $article;
+
+		$min_title_length = (int) $this->host->get($this, "min_length");
+		if (mb_strlen($article["title"]) < $min_title_length) return $article;
+
+		$owner_uid = $article["owner_uid"];
+		$feed_id = $article["feed"]["id"];
+
+		$title_escaped = db_escape_string($article["title"]);
+
+		$result = db_query("SELECT MAX(SIMILARITY(title, '$title_escaped')) AS ms
+		  FROM ttrss_entries, ttrss_user_entries WHERE ref_id = id AND
+		  date_entered >= NOW() - interval '1 day' AND
+		  feed_id != $feed_id AND
+		  owner_uid = $owner_uid");
+
+		$similarity_result = db_fetch_result($result, 0, "ms");
+
+		//_debug("similarity result: $similarity_result");
+
+		if ($similarity_result >= $similarity) {
+			$article["force_catchup"] = true;
+		}
+
+		return $article;
+
+	}
+
+	function api_version() {
+		return 2;
+	}
+
+}
+?>