ColumnStore Information Functions
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MariaDB ColumnStore Information Functions are selectable pseudo functions that return MariaDB ColumnStore specific “meta” information to ensure queries can be locally directed to a specific node. These functions can be specified in the projection (SELECT), WHERE, GROUP BY, HAVING and ORDER BY portions of the SQL statement and will be processed in a distributed manner.
| Function | Description |
|---|---|
| idbBlockId(column) | The Logical Block Identifier (LBID) for the block containing the physical row |
| idbDBRoot(column) | The DBRoot where the physical row resides |
| idbExtentId(column) | The Logical Block Identifier (LBID) for the first block in the extent containing the physical row |
| idbExtentMax(column) | The max value from the extent map entry for the extent containing the physical row |
| idbExtentMin(column) | The min value from the extent map entry for the extent containing the physical row |
| idbExtentRelativeRid(column) | The row id (1 to 8,388,608) within the column's extent |
| idbLocalPm() | The PM from which the query was launched. This function will return NULL if the query is launched from a standalone UM |
| idbPartition(column) | The three part partition id (Directory.Segment.DBRoot) |
| idbPm(column) | The PM where the physical row resides |
| idbSegmentDir(column) | The lowest level directory id for the column file containing the physical row |
| idbSegment(column) | The number of the segment file containing the physical row |
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