Allow transaction isolation level to be changed

Bucardo.pm

@@ -2877,6 +2877,11 @@ sub start_kid {
         ## Add a note to the syncrun table
         $sth{kid_syncrun_update_status}->execute("Begin txn (KID $$)", $syncname);
 
+        ## Figure out our isolation level. Only used for Postgres
+        ## All others are hard-coded as 'serializable'
+        my $isolation_level = defined $sync->{isolation_level} ? $sync->{isolation_level} : 
+            $config{isolation_level} || 'serializable';
+
         ## Commit so our dbrun and syncrun stuff is visible to others
         ## This should be done just before we start transactions on all dbs
         $maindbh->commit();
@@ -2893,7 +2898,7 @@ sub start_kid {
             $x->{dbh}->rollback();
 
             if ($x->{dbtype} eq 'postgres') {
-                $x->{dbh}->do('SET TRANSACTION ISOLATION LEVEL SERIALIZABLE READ WRITE');
+                $x->{dbh}->do(qq{SET TRANSACTION ISOLATION LEVEL $isolation_level READ WRITE});
                 $self->glog(qq{Set database "$dbname" to serializable read write}, LOG_DEBUG);
             }
 

bucardo

@@ -3639,6 +3639,7 @@ sub add_sync {
         onetimecopy              onetimecopy          =0|1|2           null
         lifetime                 lifetime             interval         null
         maxkicks                 maxkicks             numeric          null
+        isolation_level|txnmode  isolation_level      0                null
         rebuild_index|rebuildindex   rebuild_index    numeric          null
         tables                   tables               0                skip
     };
@@ -3653,6 +3654,10 @@ sub add_sync {
             value => 'fullcopy',
             new_defaults => 'autokick|F stayalive|F kidsalive|F',
         },
+        {
+            field => 'isolation_level',
+            dash_to_white => 1,
+        }
     ];
 
     my ( $dbcols, $cols, $phs, $vals ) = process_simple_args({
@@ -3998,7 +4003,10 @@ sub update_sync {
                 die "Invalid setting: $setting\n";
             }
 
-            ## Normalize things like t/f 0/1 others?
+            ## Do any magic we need
+            if ($setting eq 'isolation_level') {
+                $value =~ s/_/ /g;
+            }
 
             ## Try setting it
             $SQL = "UPDATE sync SET $setting=? WHERE name = ?";
@@ -8102,11 +8110,15 @@ sub process_simple_args {
         for my $mline (@{$arg->{morph}}) {
             if (exists $mline->{field}) {
                 next unless exists $dbcol{$mline->{field}};
-                next if $dbcol{$mline->{field}} ne $mline->{value};
-                for my $change (split /\s+/ => $mline->{new_defaults}) {
-                    my ($f,$v) = split /\|/ => $change;
-                    next if exists $dbcol{$f};
-                    $dbcol{$f} = $v;
+                if (exists $mline->{new_defaults}) {
+                    for my $change (split /\s+/ => $mline->{new_defaults}) {
+                        my ($f,$v) = split /\|/ => $change;
+                        next if exists $dbcol{$f};
+                        $dbcol{$f} = $v;
+                    }
+                }
+                if (exists $mline->{dash_to_white}) {
+                    $dbcol{$mline->{field}} =~ s/_/ /g;
                 }
             }
             else {
@@ -10077,7 +10089,7 @@ what to replicate from where to where. The supported parameters are:
 
 =item C<name>
 
-The name of the sync.
+The name of the sync. Required.
 
 =item C<dbs>
 
@@ -10104,6 +10116,11 @@ Number of seconds a KID can live before being reaped.
 
 Number of times a KID may be kicked before being reaped.
 
+=item C<isolation_level>
+
+The transation isolation level this sync should use.
+Only choices are "serializable" and "repeatable read"
+
 =item C<conflict_strategy>
 
 The conflict resolution strategy to use in the sync. Supported values:
@@ -10449,6 +10466,11 @@ Directory to store the flatfile output inside of. Default: C<.>.
 
 Regex to make sure we don't accidentally run where we should not. Default: None.
 
+=item C<isolation_level>
+
+The transaction isolation level all sync should use. Defaults to 'serializable'. 
+The only other valid option is 'repeatable read'
+
 =item C<kid_deadlock_sleep>
 
 How long to sleep in seconds if we hit a deadlock error. Default: C<0.5>.

bucardo.schema

@@ -161,6 +161,7 @@ default_conflict_strategy|bucardo_latest|Default conflict strategy for all syncs
 email_debug_file||File to save a copy of all outgoing emails to
 flatfile_dir|.|Directory to store the flatfile output inside of
 host_safety_check||Regex to make sure we don't accidentally run where we should not
+isolation_level|serializable|Default isolation level: can be serializable or repeatable read
 piddir|/var/run/bucardo|Directory holding Bucardo PID files
 reason_file|bucardo.restart.reason.txt|File to hold reasons for stopping and starting
 semaphore_table|bucardo_status|Table to let apps know a sync is ongoing
@@ -405,6 +406,7 @@ CREATE TABLE bucardo.sync (
   onetimecopy        SMALLINT    NOT NULL DEFAULT 0,
   lifetime           INTERVAL        NULL,                   -- force controller and kids to restart
   maxkicks           INTEGER     NOT NULL DEFAULT 0,         -- force controller and kids to restart
+  isolation_level    TEXT            NULL DEFAULT 'serializable',
   cdate              TIMESTAMPTZ NOT NULL DEFAULT now()
 );
 COMMENT ON TABLE bucardo.sync IS $$Defines a single replication event from a herd to one or more target databases$$;
@@ -419,6 +421,9 @@ ALTER TABLE bucardo.dbgroup ADD CONSTRAINT dbgroup_name_sane CHECK (name ~ E'^[a
 ALTER TABLE bucardo.sync    ADD CONSTRAINT sync_name_sane
   CHECK (name ~ E'^[a-zA-Z]\\w*$' AND lower(name) NOT IN ('pushdelta','fullcopy','swap'));
 
+ALTER TABLE bucardo.sync    ADD CONSTRAINT sync_isolation_level
+  CHECK (isolation_level IS NULL OR (LOWER(isolation_level) IN ('serializable', 'repeatable read')));
+
 CREATE SEQUENCE bucardo.customcode_id_seq;
 CREATE TABLE bucardo.customcode (
   id        INTEGER     NOT NULL DEFAULT nextval('customcode_id_seq'),