Fix MySQL VARBINARY column creation

Some versions of MySQL/MariaDB auto-convert large VARBINARY() to BLOB,
others return errors. Knowing current MAX_SCRIPT gets converted to
MEDIUMBLOB, explicitly convert VARBINARY(MAX_SCRIPT) to MEDIUMBLOB.

Fixes #227

Abe/DataStore.py

@@ -95,10 +95,9 @@
 PUBKEY_ID_NETWORK_FEE = NULL_PUBKEY_ID
 
 # Size of the script and pubkey columns in bytes.
-MAX_SCRIPT = 1000000
-MAX_PUBKEY = 65
-
-NO_CLOB = 'BUG_NO_CLOB'
+MAX_SCRIPT = SqlAbstraction.MAX_SCRIPT
+MAX_PUBKEY = SqlAbstraction.MAX_PUBKEY
+NO_CLOB = SqlAbstraction.NO_CLOB
 
 # XXX This belongs in another module.
 class InvalidBlock(Exception):

Abe/SqlAbstraction.py

@@ -19,6 +19,8 @@
 import re
 import logging
 
+MAX_SCRIPT = 1000000
+MAX_PUBKEY = 65
 NO_CLOB = 'BUG_NO_CLOB'
 STMT_RE = re.compile(r"([^']+)((?:'[^']*')?)")
 
@@ -197,6 +199,9 @@ def ret(x):
             pass
         elif val == 'mysql':
             transform_stmt = sql._transform_concat(transform_stmt)
+            # Also squeeze in MySQL VARBINARY length fix
+            # Some MySQL version do not auto-convert to BLOB
+            transform_stmt = sql._transform_varbinary(transform_stmt)
 
         transform_stmt = sql._append_table_epilogue(transform_stmt)
 
@@ -430,6 +435,13 @@ def ret(stmt):
             return fn(concat_re.sub(repl, stmt))
         return ret
 
+    def _transform_varbinary(sql, fn):
+        varbinary_re = re.compile(r"VARBINARY\(" + str(MAX_SCRIPT) + "\)")
+        def ret(stmt):
+            # Suitable for prefix+length up to 16,777,215 (2^24 - 1)
+            return fn(varbinary_re.sub("MEDIUMBLOB", stmt))
+        return ret
+
     def _append_table_epilogue(sql, fn):
         epilogue = sql.config.get('create_table_epilogue', "")
         if epilogue == "":