checksums-tweaks.diff

diff --git a/doc/src/sgml/wal.sgml b/doc/src/sgml/wal.sgml
index 123638b..b0d082a 100644
--- a/doc/src/sgml/wal.sgml
+++ b/doc/src/sgml/wal.sgml
@@ -257,7 +257,7 @@
   </para>
 
   <para>
-   When attempting to recover from corrupt data it may be necessarily to bypass the checksum
+   When attempting to recover from corrupt data it may be necessary to bypass the checksum
    protection in order to recover data. To do this, temporarily set the configuration parameter
    <xref linkend="guc-ignore-checksum-failure" />.
   </para>
@@ -287,15 +287,17 @@
     be visible to the process enabling checksums. It will also, for each database,
     wait for all pre-existing temporary tables to get removed before it finishes.
     If long-lived temporary tables are used in the application it may be necessary
-    to terminate these application connections to allow the checksummer process
-    to complete.
+    to terminate these application connections to allow the process to complete.
+    Information about open transactions and connections with temporary tables is
+    written to log.
    </para>
 
    <para>
     If the cluster is stopped while in <literal>inprogress</literal> mode, for
     any reason, then this process must be restarted manually. To do this,
     re-execute the function <function>pg_enable_data_checksums()</function>
-    once the cluster has been restarted.
+    once the cluster has been restarted. It is not possible to resume the work,
+    the process has to start from scratch.
    </para>
 
    <note>
@@ -317,6 +319,7 @@
     <para>
      <literal>template0</literal> is by default not accepting connections, to
      enable checksums you'll need to temporarily make it accept connections.
+     See <xref linkend="sql-alterdatabase" /> for details.
     </para>
    </note>
 
diff --git a/src/backend/access/transam/xlogfuncs.c b/src/backend/access/transam/xlogfuncs.c
index 67b9cd8..b76b268 100644
--- a/src/backend/access/transam/xlogfuncs.c
+++ b/src/backend/access/transam/xlogfuncs.c
@@ -700,6 +700,11 @@ pg_backup_start_time(PG_FUNCTION_ARGS)
 	PG_RETURN_DATUM(xtime);
 }
 
+/*
+ * Disables checksums for the cluster, unless already disabled.
+ *
+ * Has immediate effect - the checksums are set to off right away.
+ */
 Datum
 disable_data_checksums(PG_FUNCTION_ARGS)
 {
@@ -718,6 +723,12 @@ disable_data_checksums(PG_FUNCTION_ARGS)
 	PG_RETURN_VOID();
 }
 
+/*
+ * Enables checksums for the cluster, unless already enabled.
+ *
+ * Supports vacuum-like cost-based throttling, to limit system load.
+ * Starts a background worker that updates checksums on existing data.
+ */
 Datum
 enable_data_checksums(PG_FUNCTION_ARGS)
 {
diff --git a/src/backend/postmaster/checksumhelper.c b/src/backend/postmaster/checksumhelper.c
index 84a8cc8..e1c34e8 100644
--- a/src/backend/postmaster/checksumhelper.c
+++ b/src/backend/postmaster/checksumhelper.c
@@ -653,6 +653,8 @@ BuildDatabaseList(void)
 
 		db->dboid = HeapTupleGetOid(tup);
 		db->dbname = pstrdup(NameStr(pgdb->datname));
+		elog(WARNING, "attempts = %d", db->attempts);
+		db->attempts = 0;
 
 		DatabaseList = lappend(DatabaseList, db);