E-Maj - Release notes
---------------------
0.10.0
------
Enhancements:
  - on PostgreSQL 9.1 and later, E-Maj can be installed with a SQL "CREATE 
    EXTENSION" statement. If this version is already installed using the 
    usual script, it can also be transformed into EXTENSION.
  - create a new type of rollback: logged rollback, i.e. rollback executed 
    without disabling the log triggers. As a result, the application table 
    updates performed by the logged rollback are also recorded in emaj log 
    tables, and a logged rollback can be ... rollbacked too! Two marks are 
    automatically set to represent both before and after rollback states of 
    the table group.
  - a new emaj_delete_before_mark_group() function deletes all marks prior 
    (and not including) a given mark. With this functions, it is easy to let 
    groups in LOGGING state during a long period, without being limited by 
    the disk space for log tables. The drawback is the time needed to 
    delete large amount of logs, as log tables cannot be TRUNCATEd.
  - a new emaj_get_previous_mark_group() function returns the name of the 
    mark that immediately precedes a given date and time for a group. This 
    may help in using the emaj_delete_before_mark_group() function.
  - emaj_delete_mark_group() function now returns 1 (i.e. the number of 
    deleted mark), to be consistent with the data returned by the new 
    emaj_delete_before_mark_group() function.
  - the E-Maj administrator can set priority order between tables when he 
    describes a group content in emaj_grpdef table. This lets the emaj 
    administrator manage a processing order that minimize deadlock risks. 
    A new column, named grpdef_priority, and that can be left to NULL, 
    handles this concept. In emaj operations and in particular when locks 
    are set on tables, tables are processed in ascending order of priority, 
    NULLs being processed last, and in alphabetic order for schema name + 
    table name for tables described with same priority level. 
  - a new set of functions give the E-Maj administrator to start, stop,  
    set marks or rollback on a set of groups in a single operation and 
    transaction. emaj_start_groups, emaj_stop_groups, emaj_set_mark_groups, 
    emaj_rollback_groups, emaj_logged_rollback_groups and 
    emaj_rollback_and_stop_groups take as first argument an array of group 
    names.
  - emaj_param rows describing parameters default values are no longer 
    inserted at installation time. The default values are only set when 
    needed in functions. To change the default values, E-Maj administrator 
    needs to insert rows into emaj_param (instead of update them).
  - a new emaj_comment_group function sets (or resets) a comment on an 
    existing group.
  - a new emaj_comment_mark_group function sets (or resets) a comment on an 
    existing mark.
  - the general log_only parameter is replaced by a parameter set at group 
    level. A new optional boolean parameter is added to the 
    emaj_create_group() function, indicating whether the new group supports 
    rollback operations or not. By creating 'audit_only' groups (i.e. "non 
    rollbackable"), it is possible to activate log on tables that do not have 
    any primary key.
  - in each log table created by emaj_create_group() function, add an 
    emaj_inet_addr column, as a complement to the emaj_user column, to 
    register the ip address of the user who has generated the table update.
  - in emaj_log_stat_group() and emaj_detailed_log_stat_group(), empty 
    strings can be supplied as mark names. In such a case, there are 
    processed as NULL values.
  - allow use of searching or deleting marks for groups in IDLE state.
  - in parallel rollback processing, "subgroups" are now named "sessions" 
    to avoid confusion in multi-groups rollbacks.
  - in emaj_estimate_rollback_duration(), check that the group is in LOGGING 
    state.
  - in emaj_create_group(), explicitely check that no table or sequence 
    already belong to another created group.
  - in emaj_hist table, add a column containing the id of the insertion 
    transaction.
  - a comment has been added to all E-Maj tables, types and roles, as well 
    as to all functions callable by users.
  - a check is performed at the beginning of the E-Maj installation to be 
    sure that the current postgres version is compatible with E-Maj, the user 
    performing the installation is a superuser and tspemaj tablespace exists.
  - a check on the max_prepared_transaction is performed at installation 
    time and a warning is reported if the setting would block the use of the 
    parallel rollback feature.
  - add a check at group creation, set mark and rollback times to verify that 
    the group has been created with a compatible postgres version (for 
    instance, a group created in 8.3 should not be directly used in 8.4).

Bug fixes:
  - in emaj_create_group(), check the supplied group name is not null, and 
    not empty.
  - during emaj_start_group() avoid double lock of tables and reoder events
    in the emaj_hist table.
  - in emaj_verify_all() function, add a check on orphan truncate functions.
  - a missing check has been added in internal _verify_group() function.
  - to avoid potential data corruption at rollback time if the system date 
    and time changes during E-Maj activity period, use serial id instead of 
    timestamp for emaj_mark, emaj_sequence and emaj_seq_hole tables content 
    management.
  - change the primary key columns identification. Starting from pg 9.0, 
    column names must be read from pg_attribute with the table's definition, 
    using pg_index.indkey, as the column names with the index definition is 
    not safe anymore in case of column renaming.

0.9.1
-----
Enhancements:
  - emaj_snap_group(): avoid setting explicit locks on tables because it is 
    not necessary to get a coherent image of all tables of the group.
  - the emaj_log_stat_group() function has been refactored. A new internal 
    _log_stat_table() function has been created.
  - the group_creation_datetime column of the emaj_group table is now 
    initialized with the transaction timestamp instead of the clock timestamp.
  - main functions set a lock on the emaj_group row representing the working 
    group to prevent simultaneous execution of these functions.
  - in emaj_start_group() and emaj_set_mark_group() functions, a mark name may 
    contain '%' wild characters. They are automatically replaced by a sequence 
    of digits from the current time.
  - while locking tables of a group, if a deadlock occurs, the locking 
    operation is cancelled and retried up to 5 times before the transaction 
    aborts.  The comment in the history table reports the number of locked 
    tables and the number of deadlocks encountered.

Bug fixes:
  - fix a case of infinite wait on parallel rollback at foreign key processing 
    when several tables affected to different sub-groups have a foreign key 
    referencing a table that has no row to rollback.
  - in emaj_start_group() and emaj_set_mark_group() functions, avoid empty or 
    NULL mark names. If the supplied mark name is NULL or empty, a name is 
    automaticaly generated as "MARK_" followed by digits from the current time.
  - fix an invalid column name referenced in emaj_delete_mark_group() function.
  - in emaj_delete_mark_group() function, fix an erroneous information 
    inserted into the emaj_hist table.
  - during emaj_drop_group() operation, delete now all rows related to the 
    tables belonging to the dropped group from emaj_sequence and emaj_seq_hole 
    tables.
  - fix a bug in the E-Maj history table purge. If a group is in logging state 
    for a longer period than the history retention delay ('history_retention' 
    parameter), the oldest events in the history were unintentionly purged.
  - set appropriate grants to internal functions _forbid_truncate_fnct().
  - fix the postgres version detection for alpha or beta releases version 
    patterns.
  - fix a minor bug in reporting list of existing triggers on application 
    table at emaj_create_group time.
  - use a more robust lack of primary key detection.

0.9.0
-----
Enhancements:
  - a new emaj_estimate_rollback_duration() function computes an approximate 
    value for the duration of a rollback operation. It uses statistics 
    recorded in the new emaj_rlbk_stat table, as well as 4 new parameters.
  - the emaj_set_mark_group function now returns the number of processed 
    tables and sequences as other main emaj functions.
  - add a check in emaj_log_stat_group and emaj_detailed_log_stat_group 
    functions if the supplied first mark is greater than the last_mark.
  - in emaj_detailed_log_stat_group function, change the INS/UPD/DEL values 
    returned for emaj_verb column into more explicit terms (INSERT/UPDATE/
    DELETE).
  - emaj_detailed_log_stat_group, emaj_delete_mark and emaj_rename_mark 
    functions now accept EMAJ_LAST_MARK keyword as existing mark names.
  - add a check at mark creation times to forbide EMAJ_LAST_MARK name.
  - split column hist_type from emaj_hist table into 2 columns: hist_function 
    and hist_event
  - during rollback operations, move the rollback of application sequences at 
    the very end of the operation, as these rollback (ALTER SEQUENCE) are not 
    transaction safe.
  - log sequences are now reset at emaj_reset_group or emaj_start_group time.
    This should avoid potential long term issue if the log sequence reaches 
    the upper limit of serial id.
  - starting from postgres version 8.4, a trigger is created on all tables 
    belonging to a group in order to forbid TRUNCATE SQL verb during E-Maj 
    logging time. These triggers are named <schema>_<table>_emaj_trunc_trg. 
    They all call a new emaj._forbid_truncate_fnct() function. The log trigger 
    names change also, becoming <schema>_<table>_emaj_log_trg.

Bug Fixes:
  - in rollback_and_stop_group function, an error was abnormaly returned when 
    not all tables of the group needed to be effectively rollbacked.
  - 2 error messages in emaj_start_group() didn't include the right function 
    name.
  - during rollback operations, do not rollback the sequences associated to 
    the log tables any more. Before, if a problem occurred during a rollback 
    operation, the sequences of already rollbacked tables were left in an 
    inconsistent state.
  - fix grant issues for emaj_adm role.

0.8.0
-----
Enhancements:
  - enlarge the usage of the emaj_delete_mark_group function. It is now 
    possible to delete the first mark of a group. As a result, all rows from 
    log tables that become useless are deleted. This permits to reclaim disk 
    space in tspemaj tablespace if needed. At least one mark must remain 
    active. But a mark cannot be deleted if the group is not in LOGGING state.
  - a call to emaj_stop_group function for a group that is already in IDLE 
    state now only produces a warning instead of an error (exception).
  - minor coding improvement in emajParallelRollback.php module (better checks 
    of supplied group and mark names).
  - add a column in emaj_group to record the creation date and time of groups.
  - decrease the level of locks set at emaj_set_mark_group time from EXCLUSIVE 
    to ROW EXCLUSIVE so that locks generated by vacuum don't conflict with 
    emaj activity.
  - add an explicit ACCESS EXCLUSIVE lock at emaj_stop_group time to decrease 
    the risk of deadlock.
  - rename all internal functions by removing the 'emaj' prefix. So all emaj_ 
    functions are now the only functions callable by users.
  - add identifier of the updating transactions (txid) in log tables and the 
    txid of the emaj_set_mark_group command in the emaj_mark table. This is 
    for information purpose until now.
  - add a emaj_force_drop_group function to drop groups that cannot be dropped 
    with the standart emaj_drop_group function, because of any unconsistency 
    of these group. Create an internal _drop_group function to factorize the 
    common parts of both emaj_drop_group and emaj_force_drop_group functions.
  - add 2 roles without logging capacity: 
    - emaj_viewer can look at the log and emaj tables' content (application 
    support role can be granted this role),
    - emaj_adm can execute all (but emaj_snap_group) functions without being 
    superuser (an "emaj administrator" can be granted this role). 
  - add a emaj_rename_mark_group function to rename an existing mark.
  - an uninstall.sql script is provided to ... uninstall E-Maj components from 
    a database.
  - a minor change to execute E-Maj with PostgreSQL 9.0.
  - in emaj_create_group function, improve the check that tables have no 
    triggers that could be a problem at rollback time.
  - the name of deleted marks due to a rollback operation is recorded in the 
    history table.
  - marks that are deleted either by an emaj_rollback_group function call or 
    by an emaj_delete_mark_group function call are now physicaly deleted.
  - the primary key of emaj_mark table becomes (group-name, mark-name) instead 
    of the mark-timestamp.
  - E-Maj can be used with postgres 9.0.
  - rename emaj_log_stat_group into emaj_detailed_log_stat_group. The 
     associated emaj_log_stat_type type is renamed into 
     emaj_detailed_log_stat_type.
  - The emaj_rlbk_stat_group is renamed into emaj_log_stat_group. An 
    additional end_mark parameter allows to ask for statistics on a period of 
    time between two marks.The associated emaj_rlbk_stat_type type is renamed 
    into emaj_log_stat_type.

Bug fixes:
  - in rollback, solve problem with a loss of mark for other groups than the 
    rollbacked one.
  - in emaj_reset_group, the sequences related to log tables were not deleted 
    when application table name contained uppercase characters

0.7.1
-----
Enhancements:
  - add a emaj_snap_group function for test purpose that snaps all tables
    and sequences of a group on individual files located into a given 
    directory.
  - add a warning at create_group time if tables have (non emaj) triggers.
  - decrease the level of locks set at emaj_create_group or 
    emaj_set_mark_group time from ACCESS EXCLUSIVE (the default lock mode) 
    to EXCLUSIVE so that ACCESS SHARE locks generated by read accesses don't 
    conflict with emaj activity.
  - minor coding improvement.
  - this version is also tested with postgresql 9.0 beta 2.

Bug fixes:
  - in log_only mode, solve the problem encountered when creating log for 
    a table without primary key.
  - fix the error occuring when a emaj_reset_group was not executed prior an 
    emaj_drop_group. Take the opportunity to use cascading deletes provided by 
    foreign keys referencing emaj_group table.
  - fix the emaj_create_group function to get correct numbers of tables and 
    sequences in emaj_group table.
  - fix rollback aborts on UPDATEs when several clients accessed the 
    database in parallel resulting in both log rows for each UPDATE (one for 
    old values and the other for new values) not strictly in sequence.
  - when rollbacking a table, finaly also rollback the state of the sequence 
    associated to the log id so that the statistics produced by the 
    function emaj_rlbk_stat_group are correct after a rollback operation.
  - fix error when rollbacking tables having foreign keys with case sensitive 
    name.

0.7
---
Enhancements:
  - add a feature to perform parallel rollbacks, in order to speed up the 
    rollback operations on multi-processor servers. A PHP command is created
    for this purpose: emajParallelRollback.php.
  - the emaj_reset_group function is not necessary anymore before starting 
    a group; the log purge is automaticaly done at emaj_start_group function; 
    But the emaj_reset_function remains so user can purge log tables sooner.
  - issue a warning at emaj_create_group, emaj_start_group and 
    emaj_rollback_group if either a table of the group has a foreign key that 
    reference a table outside the group or a table of the group is referenced 
    by a table outside the group.
  - before a rollback operation, drop the foreign keys belonging to or 
    referencing any group's table and recreate them after
  - add a serial id to the emaj_hist table to avoid potential duplicate key 
    conditions if 2 events happen in the same micro-second.
  - the table previsously named emaj_group becomes emaj_group_def, column 
    names being slightly changed. This impact ts E-maj usage.
  - a new table emaj_relation, records working data about the relation 
    belonging to all created groups. It provides a stability of the group 
    composition during its entire life (between emaj_create_group and 
    emaj_drop_group function calls).
  - a new internal table emaj_group maintain the state of managed groups.
  - a new table emaj_param stores E-maj parameters. A first emaj_version 
    parameter records the current emaj version.
  - the emaj_delete_group function has been renamed into emaj_drop_group.
    This impacts E-maj usage.
  - add a parameter named 'log_only' that allow to configure E-maj in a mode 
    that disables rollback operations. This permits users to test E-maj 
    logging with tables for which a primary key is not yet created.
  - add an automatic deletion of oldest rows in the emaj_hist table. To 
    achieve this, a parameter, named 'history_retention' is created in the 
    emaj_param table, with a default value of 1 month. This value can be 
    changed by the user. This history purge is done at every emaj_start_group 
    time.
  - enhance the checks of emaj environment, by checking the internal 
    consistency at group level.
  - provide to users a function that checks that no residual functions or log 
    tables remain in the emaj environment.
  - in all rollback functions (in parallel or not) it is possible for user to 
    use the keyword 'EMAJ_LAST_MARK' as mark name. This pseudo name is 
    equivalent to the last active mark that exists for the group. It can also 
    be used in emaj_rlbk_stat_group function

Bug fixes:
  - change emaj_delete_group, emaj_start_group and emaj_reset_group functions 
    to add a check that the group to process is not in logging state

0.6
---
Enhancements:
  - add an emaj_rollback_and_stop_group function to rollback a table_group and 
    stop it at the same time. 
    This allow to not delete the rollbacked rows from log tables and then 
    speed up the rollback function when there is no need to keep any previous 
    mark active.
  - when an emaj_stop_group function is performed, the marks in emaj.marks 
    table are not physicaly deleted but their state just becomes "deleted". 
    The associated data in emaj_sequence table (that record the serial value  
    of each log table) are also not deleted. 
    This allow to find marks timestamps if log tables are used for application 
    debugging purpose.
    The emaj_reset_group function physicaly deletes the marks for the group at 
    the same time it truncates the related log tables.
    Note that deleted marks can be referenced in emaj_log_stat_group function 
    calls.
  - change column names from emaj_hist table to get a better consistency 
    between table name and columns name prefix

Bug fixes:
  - in rollback operations, don't delete the mark used to rollback to, and its 
    associated data for sequences, because it can be useful for a future use 
    if the application continues after the rollback operation.

0.5.2
-----
Bug fixes:
  - the UPDATE statements generated for the rollback functions did not handle 
    properly the columns list of the SET clause.
  - supply the right test-emaj.sql file !

0.5.1
-----
Bug fixes:
  - when a table has several indexes, the UPDATE or DELETE statements 
    generated by the emaj_rollback_group function was often erroneous.

Enhancements:
  - replace the current_timestamp default value for emaj_changed column of log 
    tables by clock_timestamp() so that every log row has its own creation 
    timestamp.

0.5
---
First released version