1.1 --- a/update/core-update.v2.0.11-v2.1.0.sql	Sun Aug 26 21:04:20 2012 +0200
     1.2 +++ b/update/core-update.v2.0.11-v2.1.0.sql	Tue Sep 25 02:32:51 2012 +0200
     1.3 @@ -414,6 +414,38 @@
     1.4  COMMENT ON TRIGGER "direct_voter_deletes_non_voter" ON "direct_voter" IS 'An entry in the "direct_voter" table deletes an entry in the "non_voter" table (and vice versa due to trigger "non_voter_deletes_direct_voter" on table "non_voter")';
     1.5  
     1.6  
     1.7 +-- different locking levels and different locking order to avoid deadlocks
     1.8 +
     1.9 +CREATE OR REPLACE FUNCTION "lock_issue"
    1.10 +  ( "issue_id_p" "issue"."id"%TYPE )
    1.11 +  RETURNS VOID
    1.12 +  LANGUAGE 'plpgsql' VOLATILE AS $$
    1.13 +    BEGIN
    1.14 +      -- The following locking order is used:
    1.15 +      -- 1st) row-level lock on the issue
    1.16 +      -- 2nd) table-level locks in order of occurrence in the core.sql file
    1.17 +      PERFORM NULL FROM "issue" WHERE "id" = "issue_id_p" FOR UPDATE;
    1.18 +      -- NOTE: The row-level exclusive lock in combination with the
    1.19 +      -- share_row_lock_issue(_via_initiative)_trigger functions (which
    1.20 +      -- acquire a row-level share lock on the issue) ensure that no data
    1.21 +      -- is changed, which could affect calculation of snapshots or
    1.22 +      -- counting of votes. Table "delegation" must be table-level-locked,
    1.23 +      -- as it also contains issue- and global-scope delegations.
    1.24 +      LOCK TABLE "member"     IN EXCLUSIVE MODE;  -- exclusive avoids deadlocks
    1.25 +      LOCK TABLE "privilege"  IN SHARE MODE;
    1.26 +      LOCK TABLE "membership" IN SHARE MODE;
    1.27 +      LOCK TABLE "policy"     IN SHARE MODE;
    1.28 +      LOCK TABLE "delegation" IN SHARE MODE;
    1.29 +      LOCK TABLE "direct_population_snapshot"     IN EXCLUSIVE MODE;
    1.30 +      LOCK TABLE "delegating_population_snapshot" IN EXCLUSIVE MODE;
    1.31 +      LOCK TABLE "direct_interest_snapshot"       IN EXCLUSIVE MODE;
    1.32 +      LOCK TABLE "delegating_interest_snapshot"   IN EXCLUSIVE MODE;
    1.33 +      LOCK TABLE "direct_supporter_snapshot"      IN EXCLUSIVE MODE;
    1.34 +      RETURN;
    1.35 +    END;
    1.36 +  $$;
    1.37 +
    1.38 +
    1.39  -- new comment on function "delete_private_data"()
    1.40  
    1.41  COMMENT ON FUNCTION "delete_private_data"() IS 'Used by lf_export script. DO NOT USE on productive database, but only on a copy! This function deletes all data which should not be publicly available, and can be used to create a database dump for publication. See source code to see which data is deleted. If you need a different behaviour, copy this function and modify lf_export accordingly, to avoid data-leaks after updating.';