[Checkins] SVN: relstorage/trunk/notes/migrate-to-1.5.txt Provide an additional script to clean out the old bytea data for the deleted column.

[Martijn Pieters]

Log message for revision 121955:
  Provide an additional script to clean out the old bytea data for the deleted column.

Changed:
  U   relstorage/trunk/notes/migrate-to-1.5.txt

-=-
Modified: relstorage/trunk/notes/migrate-to-1.5.txt
===================================================================
--- relstorage/trunk/notes/migrate-to-1.5.txt	2011-06-15 17:47:59 UTC (rev 121954)
+++ relstorage/trunk/notes/migrate-to-1.5.txt	2011-06-15 18:08:01 UTC (rev 121955)
@@ -36,6 +36,19 @@
         DROP COLUMN oldbytea;
     COMMIT;
 
+Note that DROP COLUMN does not reclaim the space occupied by the oldbytea
+column. If there is a large amount of data in the blob_chunk table, you may
+want to re-initialize the whole table by moving the data to a temporary table
+and then copying it back:
+
+    BEGIN;
+    CREATE TEMP TABLE blob_chunk_copy (LIKE blob_chunk) ON COMMIT DROP;
+    INSERT INTO blob_chunk_copy SELECT * FROM blob_chunk;
+    TRUNCATE blob_chunk;
+    INSERT INTO blob_chunk SELECT * FROM blob_chunk_copy;
+    COMMIT;
+    
+
 MySQL history-preserving
 ------------------------