From 993a9f3b23436cddb195740f518c38cd14b9cdd0 Mon Sep 17 00:00:00 2001
From: Gareth James <gareth.james@space48.com>
Date: Thu, 18 Jul 2024 23:18:55 +0100
Subject: [PATCH] Reduce impact of scan for a db large tables

uses an query to generate a query to run an RLIKE on all fields in the table, so that you only get rows return with encrypted values (and not every row), thus reducing the memory impact
---
 update-encryption.php | 11 ++++++++++-
 1 file changed, 10 insertions(+), 1 deletion(-)

diff --git a/update-encryption.php b/update-encryption.php
index 324c655..d0ebafe 100644
--- a/update-encryption.php
+++ b/update-encryption.php
@@ -113,7 +113,16 @@
         if ($skipTable)
             continue;
         
-        $data = $db->query("SELECT * FROM $table")->fetchAll(PDO::FETCH_ASSOC);
+        $sqlBuilder = "SELECT
+                CONCAT('SELECT * FROM $table WHERE ', GROUP_CONCAT('`', COLUMN_NAME, '`' SEPARATOR ' RLIKE ''^[0-9]{1}:[0-9]{1}:'' OR '), ' LIKE ''^[0-9]{1}:[0-9]{1}:''') as query
+            FROM INFORMATION_SCHEMA.COLUMNS
+            WHERE
+                TABLE_NAME = '$table'
+            AND
+                TABLE_SCHEMA = '{$config['dbname']}'";
+
+        $builtSql = $db->query($sqlBuilder)->fetch(PDO::FETCH_ASSOC);
+        $data = $db->query($builtSql['query'])->fetchAll(PDO::FETCH_ASSOC);
         if (!$data)
             continue;
         foreach ($data as $row) {