Backfill release notes for Iaf531795

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

diff --git a/maintenance/storage/blob_tracking.sql b/maintenance/storage/blob_tracking.sql
index fe7aadf..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
@@ -28,16 +32,19 @@ CREATE TABLE /*$wgDBprefix*/blob_tracking (
        -- True if the text table has been updated to point to bt_new_url
        bt_moved bool not null default 0,
 
-       PRIMARY KEY (bt_rev_id, bt_text_id),
+       -- Primary key
+       -- Note that text_id is not unique due to null edits (protection, move)
+       -- moveTextRow(), commit(), trackOrphanText()
+       PRIMARY KEY (bt_text_id, bt_rev_id),
 
        -- Sort by page for easy CGZ recompression
-       KEY (bt_moved, bt_page, bt_rev_id),
-
-       -- For fast orphan searches
-       KEY (bt_text_id),
+       -- doAllPages(), doAllOrphans(), doPage(), finishIncompleteMoves()
+       KEY (bt_moved, bt_page, bt_text_id),
 
        -- Key for determining the revisions using a given blob
+       -- Not used by any scripts yet
        KEY (bt_cluster, bt_blob_id, bt_cgz_hash)
+
 ) /*$wgDBTableOptions*/;
 
 -- Tracking table for blob rows that aren't tracked by the text table
@@ -47,4 +54,3 @@ CREATE TABLE /*$wgDBprefix*/blob_orphans (
 
        PRIMARY KEY (bo_cluster, bo_blob_id)
 ) /*$wgDBTableOptions*/;
-