From e54794f5b658992627eab5400b13199128eec0a1 Mon Sep 17 00:00:00 2001 From: Neil Johnson Date: Mon, 6 Aug 2018 21:55:54 +0100 Subject: [PATCH] Fix postgres compatibility bug --- synapse/storage/monthly_active_users.py | 19 +++++++++++++++---- 1 file changed, 15 insertions(+), 4 deletions(-) diff --git a/synapse/storage/monthly_active_users.py b/synapse/storage/monthly_active_users.py index c28c698c6c..abe1e6bb99 100644 --- a/synapse/storage/monthly_active_users.py +++ b/synapse/storage/monthly_active_users.py @@ -43,14 +43,25 @@ class MonthlyActiveUsersStore(SQLBaseStore): thirty_days_ago = ( int(self._clock.time_msec()) - (1000 * 60 * 60 * 24 * 30) ) - + # Purge stale users sql = "DELETE FROM monthly_active_users WHERE timestamp < ?" - txn.execute(sql, (thirty_days_ago,)) + + # If MAU user count still exceeds the MAU threshold, then delete on + # a least recently active basis. + # Note it is not possible to write this query using OFFSET due to + # incompatibilities in how sqlite an postgres support the feature. + # sqlite requires 'LIMIT -1 OFFSET ?', the LIMIT must be present + # While Postgres does not require 'LIMIT', but also does not support + # negative LIMIT values. So there is no way to write it that both can + # support sql = """ DELETE FROM monthly_active_users - ORDER BY timestamp desc - LIMIT -1 OFFSET ? + WHERE user_id NOT IN ( + SELECT user_id FROM monthly_active_users + ORDER BY timestamp DESC + LIMIT ? + ) """ txn.execute(sql, (self.hs.config.max_mau_value,))