From afd6046e9b25e6f2f54aab2e589bd5c6cb6a8a01 Mon Sep 17 00:00:00 2001 From: Benjamin Cogrel Date: Fri, 5 Apr 2024 08:08:44 +0200 Subject: [PATCH] Update mysql.md --- guide/databases/mysql.md | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) diff --git a/guide/databases/mysql.md b/guide/databases/mysql.md index ea479a5..dff8b95 100644 --- a/guide/databases/mysql.md +++ b/guide/databases/mysql.md @@ -13,12 +13,17 @@ Through the [MySQL](https://mysql.com) connector, Ontop is able to construct VKG The following shows the content of a sample `.properties` file that can be used to connect Ontop to MySQL: ```bash -jdbc.url = jdbc:mysql://localhost:3306/defaultdatabase +jdbc.url = jdbc:mysql://localhost:3306/defaultdatabase?useCursorFetch=true jdbc.user = user jdbc.password = password jdbc.driver = com.mysql.cj.jdbc.Driver ``` +:::warning +The parameter `useCursorFetch=true` needs to be added to the JDBC URL for streaming to be enabled. Otherwise, the JDBC driver will block until the full result set is fetched, which may cause out-of-memory exceptions when materializing or running large queries. +::: + + ## Nested Type Support Ontop implements explicit compatibility with the MySQL type `JSON` which can be used with the [flatten lens](/guide/advanced/lenses#flattenlens). However, it cannot infer the type of the flattened result column.