From 1a1f622fb2425b61b005a8449dea98bd43512e9d Mon Sep 17 00:00:00 2001
From: Aaron Weeden <aaronwee@buffalo.edu>
Date: Fri, 5 Sep 2025 15:07:56 -0400
Subject: [PATCH 1/2] Change to using unbuffered queries for data exports.

---
 classes/DataWarehouse/Data/BatchDataset.php      | 16 +++++++++++++++-
 .../Controllers/WarehouseControllerProvider.php  |  2 --
 2 files changed, 15 insertions(+), 3 deletions(-)

diff --git a/classes/DataWarehouse/Data/BatchDataset.php b/classes/DataWarehouse/Data/BatchDataset.php
index 22cdf126e0..94bc0df45d 100644
--- a/classes/DataWarehouse/Data/BatchDataset.php
+++ b/classes/DataWarehouse/Data/BatchDataset.php
@@ -83,6 +83,13 @@ class BatchDataset extends Loggable implements Iterator
      */
     private $offset;
 
+    /**
+     * The original setting of MYSQL_ATTR_USE_BUFFERED_QUERY before the query
+     * is run. After the last row is fetched, the setting is set back to this
+     * value.
+     */
+    private $originalBufferedQuerySetting;
+
     /**
      * @param RawQuery $query
      * @param XDUser $user
@@ -199,13 +206,16 @@ public function next()
      */
     public function rewind()
     {
+        $this->originalBufferedQuerySetting = $this->dbh->handle()->getAttribute(
+            PDO::MYSQL_ATTR_USE_BUFFERED_QUERY
+        );
+        $this->dbh->handle()->setAttribute(PDO::MYSQL_ATTR_USE_BUFFERED_QUERY, false);
         $this->logger->debug('Executing query');
         $this->sth = $this->query->getRawStatement($this->limit, $this->offset);
         $this->logger->debug(sprintf(
             'Raw query string: %s',
             $this->sth->queryString
         ));
-        $this->logger->debug(sprintf('Row count: %s', $this->sth->rowCount()));
         $this->currentRowIndex = 1;
         $this->currentRow = $this->getNextRow();
     }
@@ -248,6 +258,10 @@ private function getNextRow()
         $rawRow = $this->sth->fetch(PDO::FETCH_ASSOC);
 
         if ($rawRow === false) {
+            $this->dbh->handle()->setAttribute(
+                PDO::MYSQL_ATTR_USE_BUFFERED_QUERY,
+                $this->originalBufferedQuerySetting
+            );
             return false;
         }
 
diff --git a/classes/Rest/Controllers/WarehouseControllerProvider.php b/classes/Rest/Controllers/WarehouseControllerProvider.php
index 17e4494777..1bfc9dc22b 100644
--- a/classes/Rest/Controllers/WarehouseControllerProvider.php
+++ b/classes/Rest/Controllers/WarehouseControllerProvider.php
@@ -2370,7 +2370,6 @@ private static function echoRawData(
         );
         $pdo = DB::factory($query->_db_profile)->handle();
         if ($isFirstQueryInSeries) {
-            $pdo->setAttribute(PDO::MYSQL_ATTR_USE_BUFFERED_QUERY, false);
             self::echoRawDataRow($dataset->getHeader());
         }
         foreach ($dataset as $row) {
@@ -2390,7 +2389,6 @@ private static function echoRawData(
         }
         if ($isLastQueryInSeries) {
             echo "0\r\n\r\n";
-            $pdo->setAttribute(PDO::MYSQL_ATTR_USE_BUFFERED_QUERY, true);
         }
     }
 

From 2eea01d9ae39c6050d8219261d277580448ec876 Mon Sep 17 00:00:00 2001
From: Aaron Weeden <aaronwee@buffalo.edu>
Date: Fri, 5 Sep 2025 16:35:27 -0400
Subject: [PATCH 2/2] Update.

---
 classes/Rest/Controllers/WarehouseControllerProvider.php | 1 -
 1 file changed, 1 deletion(-)

diff --git a/classes/Rest/Controllers/WarehouseControllerProvider.php b/classes/Rest/Controllers/WarehouseControllerProvider.php
index 1bfc9dc22b..15251230c4 100644
--- a/classes/Rest/Controllers/WarehouseControllerProvider.php
+++ b/classes/Rest/Controllers/WarehouseControllerProvider.php
@@ -2368,7 +2368,6 @@ private static function echoRawData(
             $query,
             $logger
         );
-        $pdo = DB::factory($query->_db_profile)->handle();
         if ($isFirstQueryInSeries) {
             self::echoRawDataRow($dataset->getHeader());
         }