xenial (7) SLONIK_EXECUTE_SCRIPT.7.gz

NAME

       EXECUTE SCRIPT - Execute SQL/DDL script

SYNOPSIS

       EXECUTE SCRIPT (options);

DESCRIPTION

       Executes  a  script  containing  arbitrary  SQL statements on all nodes that are subscribed to a set at a
       common controlled point within the replication transaction stream.

       The specified event origin must be an origin of a set.  The script file must not  contain  any  START  or
       COMMIT TRANSACTION calls but SAVEPOINTS are allowed.  In addition, non-deterministic DML statements (like
       updating a field with CURRENT_TIMESTAMP) should be avoided, since the data changes  done  by  the  script
       will be different on each node.

       FILENAME = '/path/to/file'
              The name of the file containing the SQL script to execute. This might be a relative path, relative
              to the location of the slonik instance you are running, or, preferably, an absolute  path  on  the
              system where slonik is to run.

              The  contents  of the file are propagated as part of the replication data stream, so the file does
              not need to be accessible on any of the nodes.

       SQL = 'sql-string-to-execute'
              Instead of a filename the SQL statements to execute can be specified as a string literal in single
              quotes.

       EVENT NODE = ival
              (Mandatory  unless  EXECUTE  ONLY ON is given) The ID of the current origin of the set. If EXECUTE
              ONLY ON is given, EVENT NODE must specify the same node or be omitted.

       EXECUTE ONLY ON = ival
              (Optional) The ID of the only node to actually execute the script. This can be a single node value
              or  a  comma  separated list of nodes. This option causes the script to be propagated by all nodes
              but executed only on the specified nodes.  The default is to execute the script on all nodes  that
              are subscribed to the set.

       See also the warnings in “Database Schema Changes (DDL)” [not available as a man page].

       Note that this is a potentially heavily-locking operation, which means that it can get stuck behind other
       database activity.

       Note that if you need to make reference to the cluster name, you can use the token @CLUSTERNAME@; if  you
       need to make reference to the Slony-I namespace, you can use the token @NAMESPACE@; both will be expanded
       into the appropriate replacement tokens.

       This uses “schemadocddlscript_complete(p_nodes text)” [not available as a man page].

EXAMPLE

       EXECUTE SCRIPT (
          FILENAME = '/tmp/changes_2008-04-01.sql',
          EVENT NODE = 1
       );

       EXECUTE SCRIPT (
          FILENAME = '/tmp/changes_2008-04-01.sql',
          EVENT NODE = 1,
          EXECUTE ONLY ON='1,2,3'
       );

LOCKING BEHAVIOUR

       Up until the 2.0 branch, each replicated table received an exclusive lock, on the origin node,  in  order
       to  remove  the replication triggers; after the DDL script completes, those locks will be cleared. In the
       2.0 branch this is no longer the case.  EXECUTE SCRIPT won't obtain any locks on your application  tables
       though the script that you executing probably will.

       After  the  DDL script has run on the origin node, it will then run on subscriber nodes, where replicated
       tables will be similarly altered to remove replication triggers, therefore requiring that exclusive locks
       be taken out on each node, in turn.

SLONIK EVENT CONFIRMATION BEHAVIOUR

       Slonik  waits for the command submitted to the previous event node to be confirmed on the specified event
       node before submitting this command.

VERSION INFORMATION

       This command was introduced in Slony-I 1.0.

       Before Slony-I version 1.2, the entire DDL script  was  submitted  as  one  PQexec()  request,  with  the
       implication that the entire script was parsed based on the state of the database before invocation of the
       script. This means statements later in the script cannot depend on DDL changes made by earlier statements
       in the same script.  Thus, you cannot add a column to a table and add constraints to that column later in
       the same request.

       In Slony-I version 1.2, the DDL script  is  split  into  statements,  and  each  statement  is  submitted
       separately.  As  a  result,  it is fine for later statements to refer to objects or attributes created or
       modified in earlier statements.  Furthermore, in version 1.2, the slonik output  includes  a  listing  of
       each statement as it is processed, on the set origin node. Similarly, the statements processed are listed
       in slon logs on the other nodes.

       In Slony-I version 1.0, this would only lock the tables in the  specified  replication  set.  As  of  1.1
       (until 2.0), all replicated tables are locked (e.g.  - triggers are removed at the start, and restored at
       the end).  This deals with the risk that one might request DDL changes on tables in multiple  replication
       sets. With version 2.0 no locks on application tables are obtained by Slony-I

       In version 2.0, the default value for EVENT NODE was removed, so a node must be specified.

       As  of  version  2.0.7,  the log triggers on all replicated tables are checked to ensure their parameters
       match the primary key on the table. If they do not match, those tables that are exclusively locked  as  a
       result  of  the DDL request will have the triggers recreated to match the primary key. Tables that do not
       have an exclusive lock will not be corrected, but a warning  message  will  be  generated.  The  function
       repair_log_triggers(only_locked boolean) may be used manually to correct the triggers on those tables.

       As  of version 2.2 the DDL performed by an EXECUTE SCRIPT is stored in the sl_log_script table instead of
       sl_event.

                                                 10 January 2016                        SLONIK EXECUTE SCRIPT(7)