X-Git-Url: http://git.vrable.net/?a=blobdiff_plain;f=schema.sql;h=2cca99a34d367888c0c36c41d5715dcd5114ad8b;hb=a855c59ca566ee7a55fc3dda56ab70943a85ef32;hp=d225ec1f1c0cc0be002fc31ca9a74bf8b6c1c9a2;hpb=6a181a1eb21ac5f9f4f742281b6de841dac9a3c8;p=cumulus.git

diff --git a/schema.sql b/schema.sql
index d225ec1..2cca99a 100644
--- a/schema.sql
+++ b/schema.sql
@@ -7,13 +7,16 @@
 create table snapshots (
     snapshotid integer primary key,
     name text not null,
+    scheme text,
     timestamp real
 );
 
 -- List of segments which have been created.
 create table segments (
     segmentid integer primary key,
-    segment text unique not null
+    segment text unique not null,
+    path text,
+    checksum text
 );
 
 -- Index of all blocks which have been stored in a snapshot, by checksum.
@@ -36,3 +39,21 @@ create table snapshot_contents (
 );
 create unique index snapshot_contents_unique
     on snapshot_contents(blockid, snapshotid);
+
+-- Summary statistics for each segment.
+create view segment_info as select * from
+    (select segmentid, max(timestamp) as mtime,
+            sum(size) as size, count(*) as objects
+       from block_index join segments using (segmentid) group by segmentid)
+natural join
+    (select segmentid, sum(size) as used, count(*) as objects_used
+       from block_index where blockid in
+            (select blockid from snapshot_contents) group by segmentid);
+
+-- Ranking of segments to be cleaned, using a benefit function of
+-- (fraction free space)*(age of youngest object).
+create view cleaning_order as select *, (1-u)*age/(u+0.1) as benefit from
+    (select segmentid,
+            cast(used as real) / size as u, julianday('now') - mtime as age
+        from segment_info)
+where benefit > 0;