Removed encryption migration optimized search for dedup blocks as thi…

…s creates slowness and high load when there are many same blocks.

debian/changelog

@@ -1,3 +1,11 @@
+backy2 (2.13.3) unstable; urgency=low
+
+  * Removed encryption migration optimized search for dedup blocks as
+    this creates slowness and high load when there are many same blocks.
+
+ -- Daniel Kraft <[email protected]>  Tue, 16 Oct 2020 12:29:21 +0200
+
+
 backy2 (2.13.2) unstable; urgency=low
 
   * Better logging. Now we have stderr for ERRORs and above and we don't show

setup.py

@@ -1,7 +1,7 @@
 # -*- encoding: utf-8 -*-
 from setuptools import setup, find_packages
 
-version = '2.13.2'
+version = '2.13.3'
 
 setup(name='backy2',
     version=version,

src/backy2/meta_backends/sql.py

@@ -488,18 +488,8 @@ def get_block(self, uid):
         return self.session.query(Block).filter_by(uid=uid).first()
 
 
-    def get_block_by_checksum(self, checksum, preferred_encryption_version):
-        # there's this sql: order by field=value, field in order to get the specific value on top.
-        # Too bad, sqlalchemy does not support this (yes, I tried sqlalchemy.func.field). So we have
-        # to do this in python. Not too bad as there shouldn't be too many encryption versioned
-        # blocks of the same checksum.
-        # Here we prefer the block with preferred_encryption_version and next the highest encryption
-        # version number available, then decending.
-        results = sorted(self.session.query(Block).filter_by(checksum=checksum, valid=1).all(), key=lambda b: 100000 if b.enc_version==preferred_encryption_version else b.enc_version, reverse=True)
-        if not results:
-            return None
-        else:
-            return results[0]
+    def get_block_by_checksum(self, checksum, encryption_version):
+        return self.session.query(Block).filter_by(checksum=checksum, enc_version=encryption_version, valid=1).first()
 
 
     def get_blocks_by_version(self, version_uid):