IMSTAT Procedure (Data and Server Management)

BALANCE Statement

The BALANCE statement creates a temporary table from the active table and re-balances it so that the number of rows on the worker nodes are balanced as evenly as possible. The rows are balanced within ± 1 row of each other.

Example:

Rebalancing a Table

Syntax

BALANCE </ options>;

Without Arguments

The re-balancing removes any observations marked as deleted or marked for purging in the active table. A WHERE clause is observed when the data are rebalanced.

One case for re-balancing is if the data distribution for a table has become uneven due to block movement within the Hadoop Distributed File System. This can occur when nodes fail in Hadoop or Hadoop processes have exited on some nodes. Another situation where re-balancing is useful is when a partitioned table has uneven distribution across the worker nodes due to uneven sizes of the partition. This can affect the performance of all actions running in the LASR Analytic Server since typically the nodes with the most records determine the overall performance.

Rebalancing of a table removes partition and ordering information from the table.

The BALANCE statement can be used with non-distributed servers as well. However, it is less important because all records of a table reside on the same machine. It might be useful, however, to derive from a partitioned table a new table that is subject to a WHERE clause, has deleted records removed, and is not partitioned.

Optional Arguments

SAVE=table-name

saves the result table so that you can use it in other IMSTAT procedure statements like STORE, REPLAY, and FREE. The value for table-name must be unique within the scope of the procedure execution. The name of a table that has been freed with the FREE statement can be used again in subsequent SAVE= options.

TEMPEXPRESS="SAS-expressions"

TEMPEXPRESS=file-reference

specifies either a quoted string that contains the SAS expression that defines the temporary variables or a file reference to an external file with the SAS statements.

Alias

TE=

TEMPNAMES=variable-name

TEMPNAMES=(variable-list)

specifies the list of temporary variables for the request. Each temporary variable must be defined through SAS statements that you supply with the TEMPEXPRESS= option.

Alias

TN=

Details

ODS Table Names

The BALANCE statement generates the following ODS table.

ODS Table Name	Description	Option
TempTable	Information about a temporary table	Default

For information about using the ODS table with SAVE= option, see the Details section of the STORE statement.