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%SYS.Maint.Bitmap

Class %SYS.Maint.Bitmap Extends %Persistent [ Final, StorageStrategy = Default, System = 4 ]

This utility is used to compact bitmap/bitslice indices. Over time in a volatile table (think lots of INSERTs and DELETEs) the storage for a bitmap index may become less efficient. To a lesser extent index value changes, i.e. UPDATES, can also degrade bitmap performance.

This utility can by run on a live system. It will loop over all bitmap/bitslice indices in a class or namespace and compact them by either removing a chunk that is all zeros or by using $BITLOGIC() to compact the bits.

The Utility has 2 entry points: d ##class(%SYS.Maint.Bitmap).Namespace("Samples",1,1,"2014-01-17 09:00:00") d ##class(%SYS.Maint.Bitmap).OneClass("BitMap.Test",1,1)

Properties​

StartTime​

Property StartTime As %TimeStamp [ SqlColumnNumber = 4 ];

when the last Compact was started

StopTime​

Property StopTime As %TimeStamp [ SqlColumnNumber = 5 ];

Passed in Timestamp for when the compact should stop, NULL for no stop time Set to the time the compaction finshed when done.

ElapseTime​

Property ElapseTime As %Integer [ SqlColumnNumber = 6, SqlComputeCode = {s {*}=$SYSTEM.SQL.DATEDIFF("ss",{StartTime},{StopTime})}, SqlComputed, Transient ];

Namespace​

Property Namespace As %String(MAXLEN = 500) [ SqlColumnNumber = 2 ];

ClassName​

Property ClassName As %String(MAXLEN = 500) [ SqlColumnNumber = 11 ];

Namspace that was compacted Last Class Compacted, if NULL then it finished all the classes.

IndexName​

Property IndexName As %String(MAXLEN = 500) [ SqlColumnNumber = 12 ];

Last Index Compacted, if NULL then it finished all the indices.

NumberCompressed​

Property NumberCompressed As %Integer [ InitialExpression = 0, SqlColumnNumber = 7 ];

count of how many indices were compacted

Status​

Property Status As %String [ SqlColumnNumber = 3 ];

current status of the compaction Running - Compaction is underway Stopped - Compaction reached the Duration limit before finishing all Classes or encountered an error Finished - Compaction completed.

Message​

Property Message As array Of %String(MAXLEN = 30000) [ SqlColumnNumber = 13 ];

Message contains error info and lists of global that were skipped because they where not in the local DB

OldSize​

Property OldSize As %Integer [ InitialExpression = 0, SqlColumnNumber = 9 ];

NewSize​

Property NewSize As %Integer [ InitialExpression = 0, SqlColumnNumber = 10 ];

CompressionAmount​

Property CompressionAmount As %String [ SqlColumnNumber = 8, SqlComputeCode = { s {*}=$s(+{OldSize}=0:0,1:$FN(1-({NewSize}/{OldSize})*100,"",2)_" %")}, SqlComputed, Transient ];

Methods​

Namespace​

ClassMethod Namespace(ns As %String = "", NoJournal As %Boolean = 0, Display As %Boolean = 0, StopTime As %TimeStamp = "") As %Status [ PublicList = (ClassName, status), SqlProc ]

Entry point to compact all bitmaps in a namespace.
Each run records its' status in this class
If the last run did not finish then it will pick up where it stopped
This utility will only Compact globals in the default database

Parameters:

  • ns - Namespace you want to compact
  • NoJournal - Stop journaling for this Process
    • 1 to Stop Journaling
    • 0 to continue Journaling default = 0
  • Display - write info to the current device
    • 1 to write to the device
    • 0 to not write to the device default = 0
  • StopTime - Timestamp for when the utility should stop.
    • The stop time is tested after each index is finished so it could go over.
    • A value of NULL means not limit

OneClass​

ClassMethod OneClass(ClassName As %String, NoJournal As %Boolean = 0, Display As %Boolean = 0, StopTime As %TimeStamp = "", StatusObj As %RegisteredObject = "") As %Status [ PublicList = (ClassName, IndexName, StorageID, StorageType), SqlProc ]

Entry point to compact all bitmaps in one class.
Each run records its' status in this class
This utility will only Compact globals in the default database

Parameters:

  • ClassName - Class you want to compact
  • NoJournal - Stop journaling for this Process
    • 1 to Stop Journaling
    • 0 to continue Journaling default = 0
  • Display - write info to the current device
    • 1 to write to the device
    • 0 to not write to the device default = 0
  • StopTime - Timestamp for when the utility should stop. The stop time is tested after each index is finished so it could go over.
    • a value of NULL means not limit
  • StatusObj - This is either passed in from the Namespace Method or is defined in this method.
    • This value should not be passed in if you are calling this method directly

CompactMap​

ClassMethod CompactMap(ClassName As %String, MapName As %String, Display As %Boolean, StatusObj As %RegisteredObject) As %Status [ Private ]

CompactGlobal​

ClassMethod CompactGlobal(global As %String, vars As %Integer, current As %Integer, ByRef v As %String, Display As %Boolean = 0, StatusObj As %RegisteredObject) As %Status [ Private, PublicList = v ]

This method compacts any global bitmap
Called from CompactMap or CompactMapSQL it takes 3 parameters

  • global - is the root for this index, for example ^Sample.PersonI("NameIndex")
  • vars - is the number of subscripts we need to $ORDER() over
  • current - is the subscript level we are presently on

Once we get tot he final subscript level we execute the compat code.