[PATCH] Use column indexes in git-cvsserver where necessary.

[PATCH] Use column indexes in git-cvsserver where necessary.

[Shawn Pearce]

Tonight I found a git-cvsserver instance spending a lot of time in
disk IO while trying to process operations against a Git repository
with >30,000 objects contained in it.

Blowing away my SQLLite database and rebuilding all tables with
indexes on the attributes that git-cvsserver frequently runs queries
against seems to have resolved the issue quite nicely.

Since the indexes shouldn't hurt performance on small repositories
and always helps on larger repositories we should just always create
them when creating the revision storage tables.

Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
---
 git-cvsserver.perl |   14 +++++++++++++-
 1 files changed, 13 insertions(+), 1 deletions(-)

diff --git a/git-cvsserver.perl b/git-cvsserver.perl
index 08ad831..8817f8b 100755
--- a/git-cvsserver.perl
+++ b/git-cvsserver.perl
@@ -2118,9 +2118,17 @@ sub new
                 mode       TEXT NOT NULL
             )
         ");
+        $self->{dbh}->do("
+            CREATE INDEX revision_ix1
+            ON revision (name,revision)
+        ");
+        $self->{dbh}->do("
+            CREATE INDEX revision_ix2
+            ON revision (name,commithash)
+        ");
     }
 
-    # Construct the revision table if required
+    # Construct the head table if required
     unless ( $self->{tables}{head} )
     {
         $self->{dbh}->do("
@@ -2134,6 +2142,10 @@ sub new
                 mode       TEXT NOT NULL
             )
         ");
+        $self->{dbh}->do("
+            CREATE INDEX head_ix1
+            ON head (name)
+        ");
     }
 
     # Construct the properties table if required
-- 
1.4.3.g4e51

Re: [PATCH] Use column indexes in git-cvsserver where necessary.

[Martin Langhoff (CatalystIT)]

Shawn Pearce wrote:
> Tonight I found a git-cvsserver instance spending a lot of time in
> disk IO while trying to process operations against a Git repository
> with >30,000 objects contained in it.
> 
> Blowing away my SQLLite database and rebuilding all tables with
> indexes on the attributes that git-cvsserver frequently runs queries
> against seems to have resolved the issue quite nicely.
> 
> Since the indexes shouldn't hurt performance on small repositories
> and always helps on larger repositories we should just always create
> them when creating the revision storage tables.
 >
 > Signed-off-by: Shawn O. Pearce <spearce@spearce.org>

Ack.

I am thinking we need a lightweight schema versioning mechanism to 
decide whether the DB schema needs changes such as this. Too much work 
for this though. ;-)

We have a simple one in Moodle I could port when the time comes.

cheers,


martin
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