Miscellaneous Server Changes

• Allow limiting the DBLOCK requests for an application
• Remove 2 GB limit on volume files
• List users that opened a database
• Modified server config defaults
• Performance enhancements
• Administrative enhancements
• TurboIMAGE compatibility enhancements
• Miscellaneous changes

Allow limiting the DBLOCK requests for an application

The database server was enhanced to allow limiting the number of DBLOCK requests by an application.

The new [config] SessionLockLimit configuration item was added:

SessionLockLimit

This specifies the number of simultanous DBLOCK requests by an application for a specific database server. If set to zero, an unlimited number is supported. The default limit is 1000.

  [config]
  SessionLockLimit = 1000

Note: Previous versions of this document had two mistakes:

• The default SessionLockLimit value is 1000 (not 10000)
• The SessionLockLimit config item must be in the [config] section (not in the [server] section) of the config file.

The 2 GB limit on volume files was removed. As of Eloquence B.07.10 volume files up to 128 GB are supported, subject to operating system and file system limitations.

The server and utilities were modified to no longer apply a hard coded limit but use a configurable limit.

The size limit on volume files is now configurable in the server config file. It defaults to the previous limit.

The new [config] VolumeFileSizeLimit configuration item was added:

VolumeFileSizeLimit

This value specifies the max. volume size in MB. The value cannot exceed 128 GB (131072 MB). In addition the following values are supported.

• -1 = ~ 2GB (backwards compatible)
• 0 = 128 GB (unlimited)

The default value is -1 to enable full backwards compatibility.

  [config]
  VolumeFileSizeLimit = 4000

List users that opened a database

The dbctl list command was enhanced to list users that opened a specific database.

Syntax:

dbctl list dbopen [/notitle] database

For example:

$ dbctl list dbopen sample
TID  IP ADDR              M   User / Login
---- -------------------- --- -----------------------------
   9 127.0.0.1:54345      1   mike / public
     uid{102}pid{17995}pname{query3k}
  10 127.0.0.1:54382      9   root / public
     uid{0}pid{18010}pname{query3k}

Note: If the same database has been opened multiple times in the same session using different modes, only the first DBOPEN mode is displayed.

Modified server config defaults

The default values for some config items were modified to more practical values. The following configuration items are affected:

BufferCache

This configuration item specifies the server cache size (in MB). The default was changed to 64 (previous default was 5 MB)

CheckPtSize

This configuration item specifies the size limit of the trancaction journal (which resides in the transaction log volume). Once this limit is reached, a checkpoint operation is scheduled and a new journal is started. This value depends on the operating system memory and disk i/o system. The default size of the transaction journal was changed to 25 MB (previous default was 10 MB)

Previously, size based checkpointing could be disabled by setting CheckPtSize to zero. This has been changed because disabling size based checkpointing could in some cases have undesired effects and has no noticeable benefits. Instead of disabling size based checkpointing a zero value will now use the default size (25 MB).

EnableIPC

When enabled, the server uses shared memory to communicate with clients. The default was changed to EnableIPC=2 (previous default was EnableIPC=0).

• A new SyncerJournalFlushInterval configuration item was added that may be used to substantially improve performance in "sync" write mode.

  Previously, when sync write mode was used (SyncMode=1), the transaction journal was flushed to disk for every commit operation (either explicitly when using transactions or implicitly for each database call). In case of a system crash only the last committed transactions could potentially be lost and the volume integrity is typically maintained.

  The new SyncerJournalFlushInterval configuration item adds the option to specify the time (in milliseconds) after that changes to the transaction journal are pushed to disk. In case of a system crash any transactions committed during the period specified by SyncerJournalFlushInterval are lost but the volume integrity is typically maintained.

  The default value for the SyncerJournalFlushInterval configuration item is 500 ms (half a second).

  Note: This default modifies the behavior of the previous SyncMode and in case of a system crash may result in losing any transactions committed within the last 500 ms. To retain the previous SyncMode behavior the SyncerJournalFlushInterval configuration item must be set to zero.

  Note: Specifying a low SyncerJournalFlushInterval value may have a detrimental effect on performance. This will result in additional load on the I/O subsystem and also the operating system may block concurrent access to the transaction log volume(s) during a sync operation.

• The maximum number of concurrent connections has been increased to 4000 on the HP-UX platform (PA-RISC and Itanium). Windows and Linux are still limited to 1000 concurrent connections.

• The eloqdb6 database server was modified to remove the 2 GB file size limitation for dbstore/dbrestore.

Administrative enhancements

• The eloqdb6 server was changed to refuse performing a dbrestore or bimport operation when on-line backup mode is active.

  This change attempts to avoid unintentionally filling the transaction log volume which would lead to a server abort in on-line backup mode. Any database modification in on-line backup mode is temporarily saved in the transaction log volume.

  An error message like below is now returned in this case:

  dbrestore:

  Request refused, on-line backup mode is active and /force option not specified.

  bimport:

  Request refused, on-line backup mode is active and /f option not specified.

  The new dbrestore option /force and bimport option /f may be used to override this limitation.

• The previously undocumented dbrestore /all option allows to restore the security context with the database. Using this option currently causes dbrestore to fail if the user is not allowed to access the restored database.

• The dbctl syncmode command was enhanced to allow setting and returning the current status of the sync mode configuration item and the current value of SyncerJournalFlushInterval.

   usage: dbctl syncmode {ON [msec]|OFF|STATUS}
  

  For example:

   dbctl syncmode on 500
  

  Enables sync write mode and defines an SyncerJournalFlushInterval interval of 500 msec.

   dbctl syncmode on
  

  Enables sync mode. Equivalent to SyncMode=1

   dbctl syncmode off
  

  Disables sync mode. Equivalent to SyncMode=0

   dbctl syncmode status
  

  Returns status of sync mode. In case the sync mode is used and the SyncerJournalFlushInterval is nonzero it also returns the current value of SyncerJournalFlushInterval in msec.

TurboIMAGE compatibility enhancements

• Full support for TurboIMAGE btree modes was enabled. This causes the image3k DBINFO modes 113 and 209 to return information on master sets with "attached" indexes. It also enables the use of DBFIND mode 1 (if the btreemode1 flag is set) to locate records though the master set index ("superchains").

  Please note that index access (other than DBFIND mode 1) is always enabled with Eloquence, regardless whether the /INDEXED flag is set for a master set.

Miscellaneous changes

• The http status, config overview was modified to output the max. number of concurrently used user licenses since last starting the server.

• The server was modified to no longer disable forward logging persistently after a forward logging failure (eg. filled disk) or "dbctl forwardlog disable".

  Previously, disabling the foward logging was saved in the volume file. The server will now attempt to use forward logging upon restart if configured in the server config file. This change is intended to ease server management.

• The server was modified to now allow disabling of forward log when not using managed files.

  If a forward-log pipe or regular file without automatic management was configured, dbctl forwardlog disable had no effect.

• A flaw in the licensing code was corrected.