Merge "rdbms: make Database::insertSelect() stricter about replication safety"

[lhc/web/wiklou.git] / maintenance / storage / blob_tracking.sql

diff --git a/maintenance/storage/blob_tracking.sql b/maintenance/storage/blob_tracking.sql
index b136609..fbc407c 100644 (file)
--- a/maintenance/storage/blob_tracking.sql
+++ b/maintenance/storage/blob_tracking.sql
@@ -4,10 +4,14 @@
 CREATE TABLE /*$wgDBprefix*/blob_tracking (
        -- page.page_id
        -- This may be zero for orphan or deleted text
+       -- Note that this is for compression grouping only -- it doesn't need to be
+       -- accurate at the time recompressTracked is run. Operations such as a
+       -- delete/undelete cycle may make it inaccurate.
        bt_page integer not null,
 
        -- revision.rev_id
        -- This may be zero for orphan or deleted text
+       -- Like bt_page, it does not need to be accurate when recompressTracked is run.
        bt_rev_id integer not null,
 
        -- text.old_id
@@ -50,4 +54,3 @@ CREATE TABLE /*$wgDBprefix*/blob_orphans (
 
        PRIMARY KEY (bo_cluster, bo_blob_id)
 ) /*$wgDBTableOptions*/;
-