Compiling and Building Cubes

When to Recompile and Rebuild

If you make any change to a cube class or a subject area class, you must recompile that class before those changes take effect. For many changes to a cube, you must also rebuild the cube before those changes take effect.

The following table lists the required actions after changes:

*The current server locale determines the names of members of a time dimension. (See Using the Locale to Control the Names of Time Members.) If you change the locale, it is necessary to recompile and rebuild the cube.

†When you delete a dimension or a level and recompile, that does not delete the associated level tables and indices. Rebuilding the cube also does not delete the no-longer-needed level tables and indices.

Compiling a Cube

To compile a cube class in the Architect:

1. Click Compile.

   The system starts to compile the class and displays a dialog box that shows progress.

   If you have made changes that you have not yet saved, the system saves them before compiling the cube.

2. Click OK.

Or open the cube class in Studio and compile it in the same way that you compile other classes.

When you compile a cube class, the system automatically generates the fact table and all related classes if needed. If the fact table already exists, the system regenerates it only if it is necessary to make a structural change.

If there are any cached results for this cube, the system purges them.

Building a Cube

The phrase building a cube refers to two tasks: adding data to the fact table and other tables and building the indices used to access this data.

To perform a full cube build in the Architect:

1. Click Build.

   The system displays a dialog box.

   Note that the Build option may be greyed out. In this case, you must compile the cube before performing a build.

2. Optionally specify a value for Maximum Number of Records to Build.

   By default, the system iterates through all records in the source table and builds the same number of records to the fact table. You can override this behavior when you build the cube. If you specify the Maximum Number of Records to Build option, the system iterates through only that number of records. The result is a smaller fact table that the system builds more quickly.

   If the Maximum Number of Records to Build field is initialized with a number, that means that the cube class overrides the default behavior. (For details, see the maxFacts attribute for <cube> in Reference Information for Cube Classes.) In this case, you can either use the value provided by the cube class or enter a smaller value.

3. Select Build Everything in the Build Option section of the dialog box.

4. Click Build.

   The system starts to build the cube and displays progress as it does so. The Compile button is deactivated (greyed out) for the duration of the build.

   Note:

   Clicking the Close button during the build process does not interrupt the build process. If you choose to close the build dialog, you may reopen it at a later time to see the current state of the build process. If the build completes while the dialog is closed, the dialog will reappear to notify the user of build completion.

5. Click Done.

The cube is then available for use as described in Using the Analyzer.

Using Selective Build

You can use the Selective Build feature to build certain elements in a cube without rebuilding the entire cube and experiencing the attendant downtime. For example, if you recently made changes to a specific dimension or have source data changes that affect only one dimension, you can use Selective Build to build the relevant levels in that dimension. You can also use Selective Build to build a recently added level, measure, or relationship.

You can use Selective Build to build specific levels, measures, or relationships in a cube. More specifically, when you use Selective Build, columns in the fact tables (which each correspond to a level, measure, or relationship) are built. Using Selective Build on a cube does not trigger a need to update that cube’s dependent cubes.

A cube may inherit elements of its definition from another cube. When Selective Build is enabled for a cube inherited by another, the inheriting cube is able to read the designated factNumbers in the supercube definition and assign factNumbers to the subcube definition accordingly. The subcube does not assume that the factNumbers of the supercube remain the same, and therefore regenerates all of its own factNumbers. This protects the current cube from any changes in the supercube that might have been assigned a factNumber that conflicts with a compiled factNumber in the current cube.

Building the Cube Programmatically

To build the cube programmatically, execute the %BuildCube()Opens in a new tab class method of the %DeepSee.UtilsOpens in a new tab class. This method has the following signature:

classmethod %BuildCube(pCubeName As %String, pAsync As %Boolean = 1,  pVerbose As %Boolean = 1, 
                        pIndexOnly As %Boolean = 1, pMaxFacts As %Boolean = 0, pTracking As %Boolean = 0, 
                        ByRef pBuildStatistics As %String = "", pFactList As %String) as %Status

Where:

• pCubeName is the logical name of the cube as given in its XData block; this is not case-sensitive.

• pAsync controls whether the system performs the build in multiple background processes. If this argument is true, the system uses multiple processes and does not return until they are all complete. If this argument is false, the system uses a single process and does not return until it is complete.

  Note:

  If you have specified the cube option Initial build order, the system ignores the value of pAsync and uses a single process to build the cube. These options are described in Specifying Cube Options.

  WARNING:

  

  Custom code for build processes must not invoke HALT. Terminating a DeepSee agent may cause a cascade of lower priority agent terminations and result in the build hanging due to a lack of available agents for new tasks.

• pVerbose controls whether the method writes status information. If this argument is 1, the system writes status updates to the command line. (This argument does not affect whether the method writes build errors or other logging information.)

• pIndexOnly controls whether the method only updates the indices. If this argument is 1, the system only updates the indices of the fact table.

• pMaxFacts specifies the maximum number of rows in the fact table. This determines the number of rows of the base table that the system uses when building the cube.

  If pMaxFacts is 0, the default, all rows of the base table are processed.

• pTracking is for internal use.

• pBuildStatistics returns an array of information about the cube build. This array has the following nodes:

  Node	Value
  pBuildStatistics(“elapsedTime”)	Elapsed build time, in seconds.
  pBuildStatistics(“errors”)	Number of build errors.
  pBuildStatistics(“factCount”)	Number of facts that were built and indexed.
  pBuildStatistics(“missingReferences”)	Number of missing references.
  pBuildStatistics(“expressionTime”)	Time spent processing sourceExpressions to build the cube elements.
  pBuildStatistics(“iKnowTime”)	Time spent building NLP indices.

• pFactList is a list of specific Property names in the cube's fact class. If pFactList is supplied, the build will only update the columns listed in that fact list. This list can have either comma-delimited or $LB format. The specific facts being updated will be individually marked as unavailable for queries and queries referencing dimensions based on those facts will throw an error on prepare.

This method returns a status. If errors occur during the cube build, the status code indicates the number of build errors.

For example:

 set status = ##class(%DeepSee.Utils).%BuildCube("patients")

This method writes output that indicates the following information:

• Number of processors used.

• Total elapsed time taken by the build process

• Total amount of time spent evaluating source expressions, summed across all processors.

For example:

 
Building cube [patients]
Existing cube deleted.
Fact table built:        1,000 fact(s) (2 core(s) used)
Fact indices built:      1,000 fact(s) (2 core(s) used)
Complete
Elapsed time:                  1.791514s
Source expression time:        0.798949s

If Source expression time seems too high, you should re-examine your source expressions to be sure that they are as efficient as possible; in particular, if the expressions use SQL queries, double-check that you have the appropriate indices on the tables that the queries use.

Cube Build Status

If there is a build in progress, you can monitor its progress using the %BuildStatus()Opens in a new tab method. In the Terminal, call:

  DO ##class(%DeepSee.Utils).%BuildStatus("cubeName")

If there is no build in progress, %BuildStatus() displays the timestamp of the most recent build: There is no build in progress. Last build was finished on 06/23/2020 11:31:07.

Minimizing Cube Size During Development

While you are developing a cube, you typically recompile and rebuild it frequently. If you are using a large data set, you might want to limit the number of facts in the fact table, in order to force the cube to be rebuilt more quickly. To do this, do one of the following:

• If you build the cube in the Architect, specify a value for Maximum Number of Records to Build.

• Edit the cube class in Studio and add the maxFacts attribute to the <cube> element. See Reference Information for Cube Classes.

  If you do so, be sure to remove this attribute before deployment.

• Build the cube in the Terminal and specify the pMaxFacts argument. See Building the Cube Programmatically earlier in this page.

Note that all these options are ignored during a selective build.

Using Parallel Processing During a Cube Build

If all the following items are true, the system uses multiple cores to perform the build:

• You specify pAsync as 1 when you build the cube (see Building the Cube Programmatically).

• The source for a cube is a persistent class (rather than a data connector). Data connectors are described in Implementing InterSystems Business Intelligence.

• The persistent class is bitmap-friendly.

• The Initial build order option of the cube has not been set. These options are described in Specifying Cube Options.

When you build a cube asynchronously, the system sets up %SYSTEM.WorkMgrOpens in a new tab agents to do the work, if it is possible to use parallel processing.

On rare occasions, you might need to reset these agents. To do so, use the %Reset()Opens in a new tab method of %DeepSee.UtilsOpens in a new tab. This method also clears any pending tasks and clears the result cache for the current namespace, which would have an immediate impact on any users. This method is intended for use only during development.

Build Errors

When you build a cube, pay attention to any error messages and to the number of facts that it builds and indexes. This section discusses the following topics:

• Where you can see build errors

• Fact count, which is a useful indicator of build problems in all scenarios

• Possible causes of build errors

• How to recover from build errors

For more information on troubleshooting options, see the InterSystems Developer CommunityOpens in a new tab.

Possible Causes of Build Errors

If you see build errors or unexplained discrepancies in the fact count, do the following:

1. Examine any levels that use range expressions, and verify that these levels do not drop records. See Validating Your Levels.

   An error of this kind affects the index count but not the fact count.

2. Try disabling selected dimensions or measures. Then recompile and rebuild to isolate the dimension or measure that is causing the problem.

<STORE> Errors

In some cases, the build log might include errors like the following:

ERROR #5002: ObjectScript error: <STORE>%ConstructIndices+44^Cube.cube_name.Fact.1

This error can occur when a level has a very large number of members. By default, when the system builds the indices, it uses local memory to store the indices in chunks and then write these to disk. If a level has a very large number of members, it is possible to run out of local memory, which causes the <STORE> errors.

To avoid such errors, try either of the following:

• Build the cube with a single process. To do so, use %BuildCube() in the Terminal, and use 0 for its second argument.

• In the <cube> element, specify bitmapChunkInMemory="false" (this is the default). When this cube is built using background processes, the system will use process-private globals instead of local variables (and will not be limited by local memory).

Missing Reference Errors

If your cubes have relationships to other cubes, the build log might include errors like the following:

ERROR #5001: Missing relationship reference in RelatedCubes/Patients: source ID 1 missing reference to RxHomeCity 4

This error can mean that you have built the cubes in the wrong order. See Building Cubes That Have Relationships in Advanced Modeling for InterSystems Business Intelligence. Note that if you use the Cube Manager, the Cube Manager determines an appropriate build order.

The missing relationship reference error can also occur when new source data becomes available during the cube build process — that is, after only some of the cubes have been built. For example, consider the sample cubes RelatedCubes/Cities and RelatedCubes/Patients (which are available in the SAMPLES namespace). Suppose that you build the cube RelatedCubes/Cities, and after that, the source table for RelatedCubes/Patients receives a record that uses a new city. When you build the cube RelatedCubes/Patients, there will be a missing relationship reference error.

If you are certain that you have built the cubes in the correct order, see the next section for information on recovering from the errors.

Business Intelligence Task Log

The system creates an additional log file (apart from the previously described build logs). After it builds the cube or tries to build the cube, the system also writes the DeepSeeTasks_NAMESPACE.log file to the directory install-dir/mgr. You can use the %SetLoggingOptions method of the %DeepSee.WorkMgrOpens in a new tab class to turn on logging for background agents that the system used during the build process. To do so, make a call like the following:

do ##class(%DeepSee.WorkMgr).%SetLoggingOptions(,,1)

To see this file from the Management Portal, select Analytics > Admin > Logs.

The time stamps in this files use the local date and time (taking daylight saving time into account).