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-rw-r--r--sql/json_table.h16
1 files changed, 16 insertions, 0 deletions
diff --git a/sql/json_table.h b/sql/json_table.h
index beae5405d25..3560b4ca137 100644
--- a/sql/json_table.h
+++ b/sql/json_table.h
@@ -183,6 +183,22 @@ public:
into the TABLE_LIST::table_function.
Then the ha_json_table instance is created based on it in
the create_table_for_function().
+
+ == Replication: whether JSON_TABLE is deterministic ==
+
+ In sql_yacc.yy, we set BINLOG_STMT_UNSAFE_SYSTEM_FUNCTION whenever
+ JSON_TABLE is used. The reasoning behind this is as follows:
+
+ In the current MariaDB code, evaluation of JSON_TABLE is deterministic,
+ that is, for a given input string JSON_TABLE will always produce the same
+ set of rows in the same order. However one can think of JSON documents
+ that one can consider indentical which will produce different output.
+ In order to be feature-proof and withstand changes like:
+ - sorting JSON object members by name (like MySQL does)
+ - changing the way duplicate object members are handled
+ we mark the function as SBR-unsafe.
+ (If there is ever an issue with this, marking the function as SBR-safe
+ is a non-intrusive change we will always be able to make)
*/
class Table_function_json_table : public Sql_alloc