[Checkins] SVN: relstorage/branches/postgres_blob_oid/ Migration script for older 1.5.0 blob_chunk schemas on PostgreSQL.

[Martijn Pieters]

Log message for revision 121951:
  Migration script for older 1.5.0 blob_chunk schemas on PostgreSQL.

Changed:
  U   relstorage/branches/postgres_blob_oid/CHANGES.txt
  U   relstorage/branches/postgres_blob_oid/notes/migrate-to-1.5.txt

-=-
Modified: relstorage/branches/postgres_blob_oid/CHANGES.txt
===================================================================
--- relstorage/branches/postgres_blob_oid/CHANGES.txt	2011-06-15 15:37:59 UTC (rev 121950)
+++ relstorage/branches/postgres_blob_oid/CHANGES.txt	2011-06-15 17:29:09 UTC (rev 121951)
@@ -14,6 +14,9 @@
 - On Oracle and PostgreSQL, switch to storing ZODB blob in chunks up to 4GB
   (the maximum supported by cx_Oracle) or 2GB (PostgreSQL maximum blob size)
   to maximize blob reading and writing performance.
+  
+  The PostgreSQL blob_chunk schema changed to support this, see 
+  notes/migrate-to-1.5.txt to update existing databases.
 
 1.5.0b2 (2011-03-02)
 --------------------

Modified: relstorage/branches/postgres_blob_oid/notes/migrate-to-1.5.txt
===================================================================
--- relstorage/branches/postgres_blob_oid/notes/migrate-to-1.5.txt	2011-06-15 15:37:59 UTC (rev 121950)
+++ relstorage/branches/postgres_blob_oid/notes/migrate-to-1.5.txt	2011-06-15 17:29:09 UTC (rev 121951)
@@ -21,7 +21,20 @@
     ALTER TABLE object_state ALTER COLUMN state_size SET NOT NULL;
     COMMIT;
 
+If you used RelStorage a 1.5.0 version before version b3 you'll need to
+migrate your blob_chunk table schema:
 
+    BEGIN;
+    ALTER TABLE blob_chunk RENAME COLUMN chunk TO oldbytea;    
+    ALTER TABLE blob_chunk ADD COLUMN chunk OID;
+    UPDATE blob_chunk bc SET chunk = (
+        SELECT oid FROM (
+            SELECT oid, lowrite(lo_open(oid, 131072), bc.oldbytea)
+            FROM lo_create(0) o(oid)) x);
+    ALTER TABLE blob_chunk ALTER COLUMN chunk SET NOT NULL;
+    ALTER TABLE blob_chunk DROP COLUMN oldbytea;
+    COMMIT;
+
 MySQL history-preserving
 ------------------------