Merge "RCFilters: Fix typo in removing a saved query"

[lhc/web/wiklou.git] / docs / databases / postgres.txt

diff --git a/docs/databases/postgres.txt b/docs/databases/postgres.txt
index cec5186..6b266a6 100644 (file)
--- a/docs/databases/postgres.txt
+++ b/docs/databases/postgres.txt
@@ -92,6 +92,18 @@ in maintenance/tables.sql itself, as it is very strict in the
 format it expects things to be in. :)
 
 
+== MySQL differences ==
+
+The major differences between MySQL and Postgres are represented as 
+methods in the Database class. For example, implicitGroupby() is 
+true for MySQL and false for Postgres. This means that in those 
+places where the code does not add all the non-aggregate items 
+from the SELECT clause to the GROUP BY, we can add them in, but in 
+a conditional manner with the above method, as simply adding them 
+all in to the main query may cause performance problems with 
+MySQL.
+
+
 == Getting help ==
 
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