These columns collect various BLC statistics for use in performance analysis and debugging.
BLC enables data compression at the data block (DB) level of the Teradata Database file system. Compression reduces the amount of storage required for a given amount of data. The BlockLevelCompression field of DBS Control enables and disables BLC.
For more information on BLC and compression-related DBS Control settings, see Utilities.
| Column Name | Mode | Description | Data Type |
|---|---|---|---|
| FileCompDBs | count | Total number of data blocks compressed. | FLOAT |
| FileCompCPU | count | Total compression time, including any overhead. The column measures, in nanoseconds, the time it takes from the beginning of the compression operation to the end. This column is valid on SLES 11 or later systems only.
|
FLOAT |
| FilePostCompMB | count | Total number of MBs of compressed data that result from uncompressed blocks being compressed. This column is used together with the FilePreCompMB column to calculate the compression ratio. |
FLOAT |
| FilePreCompMB | count | Total number of MBs for the data block that will be compressed before any compression starts. This column is used together with the FilePostCompMB column to calculate the compression ratio. |
FLOAT |
| FileCompCylMigrs | count | Number of cylinder migrates done as part of a Ferret COMPRESS command or by the AutoTempComp background task. The AutoTempComp background task is responsible for finding the cylinders that should be compressed or decompressed based on their temperature. For more information on this background task, see Database Design. For more information on the Ferret utility, COMPRESS command, see Utilities. |
FLOAT |
| FileCompFerretDBs | count | Number of blocks compressed as a result of the compression operation called from the Ferret utility (see Utilities). | FLOAT |
| FileCompTempDBs | count | Number of data blocks compressed by the AutoTempComp background task because they were colder than the DBS Control TempBLCThresh field setting. See Database Design for more information on the DBS Control TempBLCThresh field and AutoTempComp background task. You must enable the temperature-based block-level compression (TBBLC) feature when using this column or it will return a zero. To determine if TBBLC is enabled, see EnableTempBLC in Utilities.
|
FLOAT |
| FilePreUncompMB | count | Total number of MBs for the compressed data block that will be uncompressed before uncompression starts. This column is used together with the FilePostUncompMB column to calculate the uncompression ratio. |
FLOAT |
| FilePostUncompMB | count | Total number of MBs of uncompressed data that result from compressed blocks being uncompressed. This column is used together with the FilePreUncompMB column to calculate the uncompression ratio. |
FLOAT |
| FileTempCPU | count | CPU time spent by the AutoTempComp background task either compressing or uncompressing data, including any overhead. For more information on the AutoTempComp background task, see Utilities. You must enable the temperature-based block-level compression (TBBLC) feature when using this column or it will return zero. To determine if TBBLC is enabled, see EnableTempBLC in Utilities.
Also, any time counted against this column is not counted in either the FileCompCPU or FileUncompCPU column. This column is valid on SLES 11 or later only.
|
FLOAT |
| FileUncompCPU | count | Total uncompression time, including any overhead. The column measures, in nanoseconds, the time it takes from the beginning of the uncompression operation to the end. This column is valid on SLES 11 or later only.
|
FLOAT |
| FileUnCompCylMigrs | count | Number of cylinder migrates done as part of a Ferret UNCOMPRESS command or by the AutoTempComp background task. For more information on the Ferret utility, UNCOMPRESS command, or AutoTempComp background task, see Utilities. |
FLOAT |
| FileUncompDBs | count | Total number of data blocks uncompressed. | FLOAT |
| FileUncompFerretDBs | count | Number of blocks uncompressed as a result of the uncompression operation called from the Ferret utility (see Utilities). | FLOAT |
| FileUnCompTempDBs | count | Number of data blocks uncompressed by the AutoTempComp background task because they were warmer than the DBS Control TempBLCThresh field setting. See Database Design for more information on the DBS Control TempBLCThresh field and AutoTempComp background task. You must enable the TBBLC feature when using this column or it will return zero. To determine if TBBLC is enabled, see EnableTempBLC in Utilities.
|
FLOAT |