fix(performance): Add index for scanning signinCodes by uid.

Author: rfk

lib/db/patch.js

@@ -4,4 +4,4 @@
 
 // The expected patch level of the database. Update if you add a new
 // patch in the ./schema/ directory.
-module.exports.level = 88
+module.exports.level = 89

lib/db/schema/patch-088-089.sql

@@ -0,0 +1,11 @@
+-- Add an index to walk signinCodes table by uid,
+-- which is necessary when deleting an account.
+SET NAMES utf8mb4 COLLATE utf8mb4_bin;
+
+CALL assertPatchLevel('88');
+
+CREATE INDEX `signinCodes_uid`
+ON `signinCodes` (`uid`)
+ALGORITHM = INPLACE LOCK = NONE;
+
+UPDATE dbMetadata SET value = '89' WHERE name = 'schema-patch-level';

lib/db/schema/patch-089-088.sql

@@ -0,0 +1,7 @@
+-- SET NAMES utf8mb4 COLLATE utf8mb4_bin;
+
+-- DROP INDEX `signinCodes_uid`
+-- ON `signinCodes`
+-- ALGORITHM=INPLACE, LOCK=NONE;
+
+-- UPDATE dbMetadata SET value = '88' WHERE name = 'schema-patch-level';