Tente de finaliser une bascule de log en progressions.

DECLARE
        v_current_status        int4;
        v_dummy                         record;
BEGIN
        -- ----
        -- Grab the central configuration lock to prevent race conditions
        -- while changing the sl_log_status sequence value.
        -- ----
        lock table sl_config_lock;

        -- ----
        -- Get the current log status.
        -- ----
        select last_value into v_current_status from sl_log_status;

        -- ----
        -- status value 0 or 1 means that there is no log switch in progress
        -- ----
        if v_current_status = 0 or v_current_status = 1 then
                return 0;
        end if;

        -- ----
        -- status = 2: sl_log_1 active, cleanup sl_log_2
        -- ----
        if v_current_status = 2 then
                -- ----
                -- The cleanup thread calls us after it did the delete and
                -- vacuum of both log tables. If sl_log_2 is empty now, we
                -- can truncate it and the log switch is done.
                -- ----
                for v_dummy in select 1 from sl_log_2 loop
                        -- ----
                        -- Found a row ... log switch is still in progress.
                        -- ----
                        raise notice 'Slony-I: log switch to sl_log_1 still in progress - sl_log_2 not truncated';
                        return -1;
                end loop;

                raise notice 'Slony-I: log switch to sl_log_1 complete - truncate sl_log_2';
                truncate sl_log_2;
                if exists (select * from "pg_catalog".pg_class c, "pg_catalog".pg_namespace n, "pg_catalog".pg_attribute a where c.relname = 'sl_log_2' and n.oid = c.relnamespace and a.attrelid = c.oid and a.attname = 'oid') then
                        execute 'alter table sl_log_2 set without oids;';
                end if;         
                perform "pg_catalog".setval('sl_log_status', 0);
                -- Run addPartialLogIndices() to try to add indices to unused sl_log_? table
                perform addPartialLogIndices();

                return 1;
        end if;

        -- ----
        -- status = 3: sl_log_2 active, cleanup sl_log_1
        -- ----
        if v_current_status = 3 then
                -- ----
                -- The cleanup thread calls us after it did the delete and
                -- vacuum of both log tables. If sl_log_2 is empty now, we
                -- can truncate it and the log switch is done.
                -- ----
                for v_dummy in select 1 from sl_log_1 loop
                        -- ----
                        -- Found a row ... log switch is still in progress.
                        -- ----
                        raise notice 'Slony-I: log switch to sl_log_2 still in progress - sl_log_1 not truncated';
                        return -1;
                end loop;

                raise notice 'Slony-I: log switch to sl_log_2 complete - truncate sl_log_1';
                truncate sl_log_1;
                if exists (select * from "pg_catalog".pg_class c, "pg_catalog".pg_namespace n, "pg_catalog".pg_attribute a where c.relname = 'sl_log_1' and n.oid = c.relnamespace and a.attrelid = c.oid and a.attname = 'oid') then
                        execute 'alter table sl_log_1 set without oids;';
                end if;         
                perform "pg_catalog".setval('sl_log_status', 1);
                -- Run addPartialLogIndices() to try to add indices to unused sl_log_? table
                perform addPartialLogIndices();
                return 2;
        end if;
END;