Slight tweaks to the local database to improve cleaning procedures.

[cumulus.git] / schema.sql

diff --git a/schema.sql b/schema.sql
index 6d89b4b..f406d91 100644 (file)
--- a/schema.sql
+++ b/schema.sql
@@ -8,16 +8,22 @@ create table snapshots (
     snapshotid integer primary key,
     name text not null,
     scheme text,
-    timestamp real
+    timestamp real,
+    intent 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,
+    mtime real,
+    size integer,
+    expire_time integer         -- snapshotid of latest snapshot when expired
 );
 
--- Index of all blocks which have been stored in a snapshot, by checksum.
+-- Index of all blocks which have been stored, by checksum.
 create table block_index (
     blockid integer primary key,
     segmentid integer not null,
@@ -30,28 +36,20 @@ create table block_index (
 create index block_content_index on block_index(checksum);
 create unique index block_name_index on block_index(segmentid, object);
 
--- Index tracking which blocks are used by which snapshots.
-create table snapshot_contents (
-    blockid integer,
-    snapshotid integer
+-- Summary of segment utilization for each snapshots.
+create table segments_used (
+    snapshotid integer not null,
+    segmentid integer not null,
+    utilization real
 );
-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 natural join segments 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);
+create unique index segments_used_index
+    on segments_used(snapshotid, 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;
+-- Overall estimate of segment utilization, for all snapshots combined.
+create view segment_info as
+select segmentid, mtime, size, cast(size * utilization as integer) as used,
+       utilization
+from segments join
+     (select segmentid, max(utilization) as utilization
+      from segments_used group by segmentid)
+using (segmentid);