Adding doc about compatibility

Author: moufmouf

couscous.yml

@@ -101,6 +101,9 @@ menu:
         migrating:
             text: Migrating
             relativeUrl: doc/migrating.html
+        compatibility:
+            text: Databases compatibility
+            relativeUrl: doc/compatibility.html
         internals:
             text: TDBM internals
             relativeUrl: doc/internals.html

doc/compatibility.md

@@ -0,0 +1,34 @@
+---
+title: Compatibility
+subTitle: Compatibility with databases
+currentMenu: compatibility
+---
+
+TDBM uses *Doctrine DBAL* under the hood to access your database.
+*Doctrine DBAL* provides a solid abstraction layer allowing TDBM to be compatible with many databases out of the box.
+
+TDBM is tested with these databases:
+
+- MySQL (5.7 and 8.0)
+- MariaDB (10.x)
+- PostgreSQL (tested on v12, but v9, v10 and v11 should be compatible)
+- Oracle (11g)
+
+TDBM is **not** compatible with Sqlite (because the database does not support foreign keys properly)
+
+
+# Known vendor issues
+
+## Oracle 11g
+
+### JSON columns are not supported
+
+Oracle 11g does not have a notion of JSON column and DBAL casts those columns in CLOB.
+But CLOB columns have an issue (they cannot be part of a DISTINCT query) that is used by TDBM.
+As a result, any request on a table containing a JSON column will fail.
+
+### BLOB columns are not supported
+
+Due to a limitation in the way OCI8 driver works, the Oracle database cannot accept *streams*
+in BLOB columns (it only accepts strings). But TDBM is exclusively using *streams* for BLOB
+columns. As a result, TDBM does not support any kind of BLOB column in Oracle.