From 5bd925456b7c729a28f98cc3b2ada4a37577eab7 Mon Sep 17 00:00:00 2001 From: Kevin Ansfield Date: Tue, 2 Apr 2024 13:10:02 +0100 Subject: [PATCH] Optimised email stats aggregation query for typical column usage ref https://linear.app/tryghost/issue/ENG-790/remove-use-of-sub-queries-in-email-analytics - the `delivered_at` column is typically entirely/nearly entirely filled with values meaning the `IS NOT NULL` query matches a huge number of rows that MySQL has to fetch from the index to count - using `IS NULL` switches that behaviour around as it will now match very few rows which has been shown in testing to be considerably quicker - after switching to `IS NULL` the query returns an "undelivered" count rather than a "delivered" count, in order to keep the rest of the system behaviour the same we can calculate the delivered count by subtracting the query result from the total number of emails sent which we can fetch using a very fast primary key lookup query on the `emails` table --- .../core/server/services/email-analytics/lib/queries.js | 6 ++++-- ghost/core/test/utils/fixtures/data-generator.js | 4 ++-- 2 files changed, 6 insertions(+), 4 deletions(-) diff --git a/ghost/core/core/server/services/email-analytics/lib/queries.js b/ghost/core/core/server/services/email-analytics/lib/queries.js index c641496db8a6..fbe2019fdc3a 100644 --- a/ghost/core/core/server/services/email-analytics/lib/queries.js +++ b/ghost/core/core/server/services/email-analytics/lib/queries.js @@ -41,12 +41,14 @@ module.exports = { }, async aggregateEmailStats(emailId) { - const [deliveredCount] = await db.knex('email_recipients').count('id as count').whereRaw('email_id = ? AND delivered_at IS NOT NULL', [emailId]); + const {totalCount} = await db.knex('emails').select(db.knex.raw('email_count as totalCount')).where('id', emailId).first() || {totalCount: 0}; + // use IS NULL here because that will typically match far fewer rows than IS NOT NULL making the query faster + const [undeliveredCount] = await db.knex('email_recipients').count('id as count').whereRaw('email_id = ? AND delivered_at IS NULL', [emailId]); const [openedCount] = await db.knex('email_recipients').count('id as count').whereRaw('email_id = ? AND opened_at IS NOT NULL', [emailId]); const [failedCount] = await db.knex('email_recipients').count('id as count').whereRaw('email_id = ? AND failed_at IS NOT NULL', [emailId]); await db.knex('emails').update({ - delivered_count: deliveredCount.count, + delivered_count: totalCount - undeliveredCount.count, opened_count: openedCount.count, failed_count: failedCount.count }).where('id', emailId); diff --git a/ghost/core/test/utils/fixtures/data-generator.js b/ghost/core/test/utils/fixtures/data-generator.js index d671503b014b..6a2d650fa037 100644 --- a/ghost/core/test/utils/fixtures/data-generator.js +++ b/ghost/core/test/utils/fixtures/data-generator.js @@ -731,7 +731,7 @@ DataGenerator.Content = { id: ObjectId().toHexString(), uuid: '6b6afda6-4b5e-4893-bff6-f16859e8349a', status: 'submitted', - email_count: 2, + email_count: 6, // match the number of email_recipients relations below recipient_filter: 'all', subject: 'You got mailed!', html: '

Look! I\'m an email

', @@ -745,7 +745,7 @@ DataGenerator.Content = { uuid: '365daa11-4bf0-4614-ad43-6346387ffa00', status: 'failed', error: 'Everything went south', - email_count: 3, + email_count: 0, // match the number of email_recipient relations below subject: 'You got mailed! Again!', html: '

What\'s that? Another email!

', plaintext: 'yes this is an email',